6840752: Provide out-of-the-box support for ECC algorithms
Reviewed-by: alanb, mullan, wetmore
/* *********************************************************************
*
* Sun elects to have this file available under and governed by the
* Mozilla Public License Version 1.1 ("MPL") (see
* http://www.mozilla.org/MPL/ for full license text). For the avoidance
* of doubt and subject to the following, Sun also elects to allow
* licensees to use this file under the MPL, the GNU General Public
* License version 2 only or the Lesser General Public License version
* 2.1 only. Any references to the "GNU General Public License version 2
* or later" or "GPL" in the following shall be construed to mean the
* GNU General Public License version 2 only. Any references to the "GNU
* Lesser General Public License version 2.1 or later" or "LGPL" in the
* following shall be construed to mean the GNU Lesser General Public
* License version 2.1 only. However, the following notice accompanied
* the original version of this file:
*
*
* Arbitrary precision integer arithmetic library
*
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the MPI Arbitrary Precision Integer Arithmetic library.
*
* The Initial Developer of the Original Code is
* Michael J. Fromberger.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Netscape Communications Corporation
* Douglas Stebila <douglas@stebila.ca> of Sun Laboratories.
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
*********************************************************************** */
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/* $Id: mpi.c,v 1.45 2006/09/29 20:12:21 alexei.volkov.bugs%sun.com Exp $ */
#include "mpi-priv.h"
#if defined(OSF1)
#include <c_asm.h>
#endif
#if MP_LOGTAB
/*
A table of the logs of 2 for various bases (the 0 and 1 entries of
this table are meaningless and should not be referenced).
This table is used to compute output lengths for the mp_toradix()
function. Since a number n in radix r takes up about log_r(n)
digits, we estimate the output size by taking the least integer
greater than log_r(n), where:
log_r(n) = log_2(n) * log_r(2)
This table, therefore, is a table of log_r(2) for 2 <= r <= 36,
which are the output bases supported.
*/
#include "logtab.h"
#endif
/* {{{ Constant strings */
/* Constant strings returned by mp_strerror() */
static const char *mp_err_string[] = {
"unknown result code", /* say what? */
"boolean true", /* MP_OKAY, MP_YES */
"boolean false", /* MP_NO */
"out of memory", /* MP_MEM */
"argument out of range", /* MP_RANGE */
"invalid input parameter", /* MP_BADARG */
"result is undefined" /* MP_UNDEF */
};
/* Value to digit maps for radix conversion */
/* s_dmap_1 - standard digits and letters */
static const char *s_dmap_1 =
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/";
/* }}} */
unsigned long mp_allocs;
unsigned long mp_frees;
unsigned long mp_copies;
/* {{{ Default precision manipulation */
/* Default precision for newly created mp_int's */
static mp_size s_mp_defprec = MP_DEFPREC;
mp_size mp_get_prec(void)
{
return s_mp_defprec;
} /* end mp_get_prec() */
void mp_set_prec(mp_size prec)
{
if(prec == 0)
s_mp_defprec = MP_DEFPREC;
else
s_mp_defprec = prec;
} /* end mp_set_prec() */
/* }}} */
/*------------------------------------------------------------------------*/
/* {{{ mp_init(mp, kmflag) */
/*
mp_init(mp, kmflag)
Initialize a new zero-valued mp_int. Returns MP_OKAY if successful,
MP_MEM if memory could not be allocated for the structure.
*/
mp_err mp_init(mp_int *mp, int kmflag)
{
return mp_init_size(mp, s_mp_defprec, kmflag);
} /* end mp_init() */
/* }}} */
/* {{{ mp_init_size(mp, prec, kmflag) */
/*
mp_init_size(mp, prec, kmflag)
Initialize a new zero-valued mp_int with at least the given
precision; returns MP_OKAY if successful, or MP_MEM if memory could
not be allocated for the structure.
*/
mp_err mp_init_size(mp_int *mp, mp_size prec, int kmflag)
{
ARGCHK(mp != NULL && prec > 0, MP_BADARG);
prec = MP_ROUNDUP(prec, s_mp_defprec);
if((DIGITS(mp) = s_mp_alloc(prec, sizeof(mp_digit), kmflag)) == NULL)
return MP_MEM;
SIGN(mp) = ZPOS;
USED(mp) = 1;
ALLOC(mp) = prec;
return MP_OKAY;
} /* end mp_init_size() */
/* }}} */
/* {{{ mp_init_copy(mp, from) */
/*
mp_init_copy(mp, from)
Initialize mp as an exact copy of from. Returns MP_OKAY if
successful, MP_MEM if memory could not be allocated for the new
structure.
*/
mp_err mp_init_copy(mp_int *mp, const mp_int *from)
{
ARGCHK(mp != NULL && from != NULL, MP_BADARG);
if(mp == from)
return MP_OKAY;
if((DIGITS(mp) = s_mp_alloc(ALLOC(from), sizeof(mp_digit), FLAG(from))) == NULL)
return MP_MEM;
s_mp_copy(DIGITS(from), DIGITS(mp), USED(from));
USED(mp) = USED(from);
ALLOC(mp) = ALLOC(from);
SIGN(mp) = SIGN(from);
#ifndef _WIN32
FLAG(mp) = FLAG(from);
#endif /* _WIN32 */
return MP_OKAY;
} /* end mp_init_copy() */
/* }}} */
/* {{{ mp_copy(from, to) */
/*
mp_copy(from, to)
Copies the mp_int 'from' to the mp_int 'to'. It is presumed that
'to' has already been initialized (if not, use mp_init_copy()
instead). If 'from' and 'to' are identical, nothing happens.
*/
mp_err mp_copy(const mp_int *from, mp_int *to)
{
ARGCHK(from != NULL && to != NULL, MP_BADARG);
if(from == to)
return MP_OKAY;
++mp_copies;
{ /* copy */
mp_digit *tmp;
/*
If the allocated buffer in 'to' already has enough space to hold
all the used digits of 'from', we'll re-use it to avoid hitting
the memory allocater more than necessary; otherwise, we'd have
to grow anyway, so we just allocate a hunk and make the copy as
usual
*/
if(ALLOC(to) >= USED(from)) {
s_mp_setz(DIGITS(to) + USED(from), ALLOC(to) - USED(from));
s_mp_copy(DIGITS(from), DIGITS(to), USED(from));
} else {
if((tmp = s_mp_alloc(ALLOC(from), sizeof(mp_digit), FLAG(from))) == NULL)
return MP_MEM;
s_mp_copy(DIGITS(from), tmp, USED(from));
if(DIGITS(to) != NULL) {
#if MP_CRYPTO
s_mp_setz(DIGITS(to), ALLOC(to));
#endif
s_mp_free(DIGITS(to), ALLOC(to));
}
DIGITS(to) = tmp;
ALLOC(to) = ALLOC(from);
}
/* Copy the precision and sign from the original */
USED(to) = USED(from);
SIGN(to) = SIGN(from);
} /* end copy */
return MP_OKAY;
} /* end mp_copy() */
/* }}} */
/* {{{ mp_exch(mp1, mp2) */
/*
mp_exch(mp1, mp2)
Exchange mp1 and mp2 without allocating any intermediate memory
(well, unless you count the stack space needed for this call and the
locals it creates...). This cannot fail.
*/
void mp_exch(mp_int *mp1, mp_int *mp2)
{
#if MP_ARGCHK == 2
assert(mp1 != NULL && mp2 != NULL);
#else
if(mp1 == NULL || mp2 == NULL)
return;
#endif
s_mp_exch(mp1, mp2);
} /* end mp_exch() */
/* }}} */
/* {{{ mp_clear(mp) */
/*
mp_clear(mp)
Release the storage used by an mp_int, and void its fields so that
if someone calls mp_clear() again for the same int later, we won't
get tollchocked.
*/
void mp_clear(mp_int *mp)
{
if(mp == NULL)
return;
if(DIGITS(mp) != NULL) {
#if MP_CRYPTO
s_mp_setz(DIGITS(mp), ALLOC(mp));
#endif
s_mp_free(DIGITS(mp), ALLOC(mp));
DIGITS(mp) = NULL;
}
USED(mp) = 0;
ALLOC(mp) = 0;
} /* end mp_clear() */
/* }}} */
/* {{{ mp_zero(mp) */
/*
mp_zero(mp)
Set mp to zero. Does not change the allocated size of the structure,
and therefore cannot fail (except on a bad argument, which we ignore)
*/
void mp_zero(mp_int *mp)
{
if(mp == NULL)
return;
s_mp_setz(DIGITS(mp), ALLOC(mp));
USED(mp) = 1;
SIGN(mp) = ZPOS;
} /* end mp_zero() */
/* }}} */
/* {{{ mp_set(mp, d) */
void mp_set(mp_int *mp, mp_digit d)
{
if(mp == NULL)
return;
mp_zero(mp);
DIGIT(mp, 0) = d;
} /* end mp_set() */
/* }}} */
/* {{{ mp_set_int(mp, z) */
mp_err mp_set_int(mp_int *mp, long z)
{
int ix;
unsigned long v = labs(z);
mp_err res;
ARGCHK(mp != NULL, MP_BADARG);
mp_zero(mp);
if(z == 0)
return MP_OKAY; /* shortcut for zero */
if (sizeof v <= sizeof(mp_digit)) {
DIGIT(mp,0) = v;
} else {
for (ix = sizeof(long) - 1; ix >= 0; ix--) {
if ((res = s_mp_mul_d(mp, (UCHAR_MAX + 1))) != MP_OKAY)
return res;
res = s_mp_add_d(mp, (mp_digit)((v >> (ix * CHAR_BIT)) & UCHAR_MAX));
if (res != MP_OKAY)
return res;
}
}
if(z < 0)
SIGN(mp) = NEG;
return MP_OKAY;
} /* end mp_set_int() */
/* }}} */
/* {{{ mp_set_ulong(mp, z) */
mp_err mp_set_ulong(mp_int *mp, unsigned long z)
{
int ix;
mp_err res;
ARGCHK(mp != NULL, MP_BADARG);
mp_zero(mp);
if(z == 0)
return MP_OKAY; /* shortcut for zero */
if (sizeof z <= sizeof(mp_digit)) {
DIGIT(mp,0) = z;
} else {
for (ix = sizeof(long) - 1; ix >= 0; ix--) {
if ((res = s_mp_mul_d(mp, (UCHAR_MAX + 1))) != MP_OKAY)
return res;
res = s_mp_add_d(mp, (mp_digit)((z >> (ix * CHAR_BIT)) & UCHAR_MAX));
if (res != MP_OKAY)
return res;
}
}
return MP_OKAY;
} /* end mp_set_ulong() */
/* }}} */
/*------------------------------------------------------------------------*/
/* {{{ Digit arithmetic */
/* {{{ mp_add_d(a, d, b) */
/*
mp_add_d(a, d, b)
Compute the sum b = a + d, for a single digit d. Respects the sign of
its primary addend (single digits are unsigned anyway).
*/
mp_err mp_add_d(const mp_int *a, mp_digit d, mp_int *b)
{
mp_int tmp;
mp_err res;
ARGCHK(a != NULL && b != NULL, MP_BADARG);
if((res = mp_init_copy(&tmp, a)) != MP_OKAY)
return res;
if(SIGN(&tmp) == ZPOS) {
if((res = s_mp_add_d(&tmp, d)) != MP_OKAY)
goto CLEANUP;
} else if(s_mp_cmp_d(&tmp, d) >= 0) {
if((res = s_mp_sub_d(&tmp, d)) != MP_OKAY)
goto CLEANUP;
} else {
mp_neg(&tmp, &tmp);
DIGIT(&tmp, 0) = d - DIGIT(&tmp, 0);
}
if(s_mp_cmp_d(&tmp, 0) == 0)
SIGN(&tmp) = ZPOS;
s_mp_exch(&tmp, b);
CLEANUP:
mp_clear(&tmp);
return res;
} /* end mp_add_d() */
/* }}} */
/* {{{ mp_sub_d(a, d, b) */
/*
mp_sub_d(a, d, b)
Compute the difference b = a - d, for a single digit d. Respects the
sign of its subtrahend (single digits are unsigned anyway).
*/
mp_err mp_sub_d(const mp_int *a, mp_digit d, mp_int *b)
{
mp_int tmp;
mp_err res;
ARGCHK(a != NULL && b != NULL, MP_BADARG);
if((res = mp_init_copy(&tmp, a)) != MP_OKAY)
return res;
if(SIGN(&tmp) == NEG) {
if((res = s_mp_add_d(&tmp, d)) != MP_OKAY)
goto CLEANUP;
} else if(s_mp_cmp_d(&tmp, d) >= 0) {
if((res = s_mp_sub_d(&tmp, d)) != MP_OKAY)
goto CLEANUP;
} else {
mp_neg(&tmp, &tmp);
DIGIT(&tmp, 0) = d - DIGIT(&tmp, 0);
SIGN(&tmp) = NEG;
}
if(s_mp_cmp_d(&tmp, 0) == 0)
SIGN(&tmp) = ZPOS;
s_mp_exch(&tmp, b);
CLEANUP:
mp_clear(&tmp);
return res;
} /* end mp_sub_d() */
/* }}} */
/* {{{ mp_mul_d(a, d, b) */
/*
mp_mul_d(a, d, b)
Compute the product b = a * d, for a single digit d. Respects the sign
of its multiplicand (single digits are unsigned anyway)
*/
mp_err mp_mul_d(const mp_int *a, mp_digit d, mp_int *b)
{
mp_err res;
ARGCHK(a != NULL && b != NULL, MP_BADARG);
if(d == 0) {
mp_zero(b);
return MP_OKAY;
}
if((res = mp_copy(a, b)) != MP_OKAY)
return res;
res = s_mp_mul_d(b, d);
return res;
} /* end mp_mul_d() */
/* }}} */
/* {{{ mp_mul_2(a, c) */
mp_err mp_mul_2(const mp_int *a, mp_int *c)
{
mp_err res;
ARGCHK(a != NULL && c != NULL, MP_BADARG);
if((res = mp_copy(a, c)) != MP_OKAY)
return res;
return s_mp_mul_2(c);
} /* end mp_mul_2() */
/* }}} */
/* {{{ mp_div_d(a, d, q, r) */
/*
mp_div_d(a, d, q, r)
Compute the quotient q = a / d and remainder r = a mod d, for a
single digit d. Respects the sign of its divisor (single digits are
unsigned anyway).
*/
mp_err mp_div_d(const mp_int *a, mp_digit d, mp_int *q, mp_digit *r)
{
mp_err res;
mp_int qp;
mp_digit rem;
int pow;
ARGCHK(a != NULL, MP_BADARG);
if(d == 0)
return MP_RANGE;
/* Shortcut for powers of two ... */
if((pow = s_mp_ispow2d(d)) >= 0) {
mp_digit mask;
mask = ((mp_digit)1 << pow) - 1;
rem = DIGIT(a, 0) & mask;
if(q) {
mp_copy(a, q);
s_mp_div_2d(q, pow);
}
if(r)
*r = rem;
return MP_OKAY;
}
if((res = mp_init_copy(&qp, a)) != MP_OKAY)
return res;
res = s_mp_div_d(&qp, d, &rem);
if(s_mp_cmp_d(&qp, 0) == 0)
SIGN(q) = ZPOS;
if(r)
*r = rem;
if(q)
s_mp_exch(&qp, q);
mp_clear(&qp);
return res;
} /* end mp_div_d() */
/* }}} */
/* {{{ mp_div_2(a, c) */
/*
mp_div_2(a, c)
Compute c = a / 2, disregarding the remainder.
*/
mp_err mp_div_2(const mp_int *a, mp_int *c)
{
mp_err res;
ARGCHK(a != NULL && c != NULL, MP_BADARG);
if((res = mp_copy(a, c)) != MP_OKAY)
return res;
s_mp_div_2(c);
return MP_OKAY;
} /* end mp_div_2() */
/* }}} */
/* {{{ mp_expt_d(a, d, b) */
mp_err mp_expt_d(const mp_int *a, mp_digit d, mp_int *c)
{
mp_int s, x;
mp_err res;
ARGCHK(a != NULL && c != NULL, MP_BADARG);
if((res = mp_init(&s, FLAG(a))) != MP_OKAY)
return res;
if((res = mp_init_copy(&x, a)) != MP_OKAY)
goto X;
DIGIT(&s, 0) = 1;
while(d != 0) {
if(d & 1) {
if((res = s_mp_mul(&s, &x)) != MP_OKAY)
goto CLEANUP;
}
d /= 2;
if((res = s_mp_sqr(&x)) != MP_OKAY)
goto CLEANUP;
}
s_mp_exch(&s, c);
CLEANUP:
mp_clear(&x);
X:
mp_clear(&s);
return res;
} /* end mp_expt_d() */
/* }}} */
/* }}} */
/*------------------------------------------------------------------------*/
/* {{{ Full arithmetic */
/* {{{ mp_abs(a, b) */
/*
mp_abs(a, b)
Compute b = |a|. 'a' and 'b' may be identical.
*/
mp_err mp_abs(const mp_int *a, mp_int *b)
{
mp_err res;
ARGCHK(a != NULL && b != NULL, MP_BADARG);
if((res = mp_copy(a, b)) != MP_OKAY)
return res;
SIGN(b) = ZPOS;
return MP_OKAY;
} /* end mp_abs() */
/* }}} */
/* {{{ mp_neg(a, b) */
/*
mp_neg(a, b)
Compute b = -a. 'a' and 'b' may be identical.
*/
mp_err mp_neg(const mp_int *a, mp_int *b)
{
mp_err res;
ARGCHK(a != NULL && b != NULL, MP_BADARG);
if((res = mp_copy(a, b)) != MP_OKAY)
return res;
if(s_mp_cmp_d(b, 0) == MP_EQ)
SIGN(b) = ZPOS;
else
SIGN(b) = (SIGN(b) == NEG) ? ZPOS : NEG;
return MP_OKAY;
} /* end mp_neg() */
/* }}} */
/* {{{ mp_add(a, b, c) */
/*
mp_add(a, b, c)
Compute c = a + b. All parameters may be identical.
*/
mp_err mp_add(const mp_int *a, const mp_int *b, mp_int *c)
{
mp_err res;
ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
if(SIGN(a) == SIGN(b)) { /* same sign: add values, keep sign */
MP_CHECKOK( s_mp_add_3arg(a, b, c) );
} else if(s_mp_cmp(a, b) >= 0) { /* different sign: |a| >= |b| */
MP_CHECKOK( s_mp_sub_3arg(a, b, c) );
} else { /* different sign: |a| < |b| */
MP_CHECKOK( s_mp_sub_3arg(b, a, c) );
}
if (s_mp_cmp_d(c, 0) == MP_EQ)
SIGN(c) = ZPOS;
CLEANUP:
return res;
} /* end mp_add() */
/* }}} */
/* {{{ mp_sub(a, b, c) */
/*
mp_sub(a, b, c)
Compute c = a - b. All parameters may be identical.
*/
mp_err mp_sub(const mp_int *a, const mp_int *b, mp_int *c)
{
mp_err res;
int magDiff;
ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
if (a == b) {
mp_zero(c);
return MP_OKAY;
}
if (MP_SIGN(a) != MP_SIGN(b)) {
MP_CHECKOK( s_mp_add_3arg(a, b, c) );
} else if (!(magDiff = s_mp_cmp(a, b))) {
mp_zero(c);
res = MP_OKAY;
} else if (magDiff > 0) {
MP_CHECKOK( s_mp_sub_3arg(a, b, c) );
} else {
MP_CHECKOK( s_mp_sub_3arg(b, a, c) );
MP_SIGN(c) = !MP_SIGN(a);
}
if (s_mp_cmp_d(c, 0) == MP_EQ)
MP_SIGN(c) = MP_ZPOS;
CLEANUP:
return res;
} /* end mp_sub() */
/* }}} */
/* {{{ mp_mul(a, b, c) */
/*
mp_mul(a, b, c)
Compute c = a * b. All parameters may be identical.
*/
mp_err mp_mul(const mp_int *a, const mp_int *b, mp_int * c)
{
mp_digit *pb;
mp_int tmp;
mp_err res;
mp_size ib;
mp_size useda, usedb;
ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
if (a == c) {
if ((res = mp_init_copy(&tmp, a)) != MP_OKAY)
return res;
if (a == b)
b = &tmp;
a = &tmp;
} else if (b == c) {
if ((res = mp_init_copy(&tmp, b)) != MP_OKAY)
return res;
b = &tmp;
} else {
MP_DIGITS(&tmp) = 0;
}
if (MP_USED(a) < MP_USED(b)) {
const mp_int *xch = b; /* switch a and b, to do fewer outer loops */
b = a;
a = xch;
}
MP_USED(c) = 1; MP_DIGIT(c, 0) = 0;
if((res = s_mp_pad(c, USED(a) + USED(b))) != MP_OKAY)
goto CLEANUP;
#ifdef NSS_USE_COMBA
if ((MP_USED(a) == MP_USED(b)) && IS_POWER_OF_2(MP_USED(b))) {
if (MP_USED(a) == 4) {
s_mp_mul_comba_4(a, b, c);
goto CLEANUP;
}
if (MP_USED(a) == 8) {
s_mp_mul_comba_8(a, b, c);
goto CLEANUP;
}
if (MP_USED(a) == 16) {
s_mp_mul_comba_16(a, b, c);
goto CLEANUP;
}
if (MP_USED(a) == 32) {
s_mp_mul_comba_32(a, b, c);
goto CLEANUP;
}
}
#endif
pb = MP_DIGITS(b);
s_mpv_mul_d(MP_DIGITS(a), MP_USED(a), *pb++, MP_DIGITS(c));
/* Outer loop: Digits of b */
useda = MP_USED(a);
usedb = MP_USED(b);
for (ib = 1; ib < usedb; ib++) {
mp_digit b_i = *pb++;
/* Inner product: Digits of a */
if (b_i)
s_mpv_mul_d_add(MP_DIGITS(a), useda, b_i, MP_DIGITS(c) + ib);
else
MP_DIGIT(c, ib + useda) = b_i;
}
s_mp_clamp(c);
if(SIGN(a) == SIGN(b) || s_mp_cmp_d(c, 0) == MP_EQ)
SIGN(c) = ZPOS;
else
SIGN(c) = NEG;
CLEANUP:
mp_clear(&tmp);
return res;
} /* end mp_mul() */
/* }}} */
/* {{{ mp_sqr(a, sqr) */
#if MP_SQUARE
/*
Computes the square of a. This can be done more
efficiently than a general multiplication, because many of the
computation steps are redundant when squaring. The inner product
step is a bit more complicated, but we save a fair number of
iterations of the multiplication loop.
*/
/* sqr = a^2; Caller provides both a and tmp; */
mp_err mp_sqr(const mp_int *a, mp_int *sqr)
{
mp_digit *pa;
mp_digit d;
mp_err res;
mp_size ix;
mp_int tmp;
int count;
ARGCHK(a != NULL && sqr != NULL, MP_BADARG);
if (a == sqr) {
if((res = mp_init_copy(&tmp, a)) != MP_OKAY)
return res;
a = &tmp;
} else {
DIGITS(&tmp) = 0;
res = MP_OKAY;
}
ix = 2 * MP_USED(a);
if (ix > MP_ALLOC(sqr)) {
MP_USED(sqr) = 1;
MP_CHECKOK( s_mp_grow(sqr, ix) );
}
MP_USED(sqr) = ix;
MP_DIGIT(sqr, 0) = 0;
#ifdef NSS_USE_COMBA
if (IS_POWER_OF_2(MP_USED(a))) {
if (MP_USED(a) == 4) {
s_mp_sqr_comba_4(a, sqr);
goto CLEANUP;
}
if (MP_USED(a) == 8) {
s_mp_sqr_comba_8(a, sqr);
goto CLEANUP;
}
if (MP_USED(a) == 16) {
s_mp_sqr_comba_16(a, sqr);
goto CLEANUP;
}
if (MP_USED(a) == 32) {
s_mp_sqr_comba_32(a, sqr);
goto CLEANUP;
}
}
#endif
pa = MP_DIGITS(a);
count = MP_USED(a) - 1;
if (count > 0) {
d = *pa++;
s_mpv_mul_d(pa, count, d, MP_DIGITS(sqr) + 1);
for (ix = 3; --count > 0; ix += 2) {
d = *pa++;
s_mpv_mul_d_add(pa, count, d, MP_DIGITS(sqr) + ix);
} /* for(ix ...) */
MP_DIGIT(sqr, MP_USED(sqr)-1) = 0; /* above loop stopped short of this. */
/* now sqr *= 2 */
s_mp_mul_2(sqr);
} else {
MP_DIGIT(sqr, 1) = 0;
}
/* now add the squares of the digits of a to sqr. */
s_mpv_sqr_add_prop(MP_DIGITS(a), MP_USED(a), MP_DIGITS(sqr));
SIGN(sqr) = ZPOS;
s_mp_clamp(sqr);
CLEANUP:
mp_clear(&tmp);
return res;
} /* end mp_sqr() */
#endif
/* }}} */
/* {{{ mp_div(a, b, q, r) */
/*
mp_div(a, b, q, r)
Compute q = a / b and r = a mod b. Input parameters may be re-used
as output parameters. If q or r is NULL, that portion of the
computation will be discarded (although it will still be computed)
*/
mp_err mp_div(const mp_int *a, const mp_int *b, mp_int *q, mp_int *r)
{
mp_err res;
mp_int *pQ, *pR;
mp_int qtmp, rtmp, btmp;
int cmp;
mp_sign signA;
mp_sign signB;
ARGCHK(a != NULL && b != NULL, MP_BADARG);
signA = MP_SIGN(a);
signB = MP_SIGN(b);
if(mp_cmp_z(b) == MP_EQ)
return MP_RANGE;
DIGITS(&qtmp) = 0;
DIGITS(&rtmp) = 0;
DIGITS(&btmp) = 0;
/* Set up some temporaries... */
if (!r || r == a || r == b) {
MP_CHECKOK( mp_init_copy(&rtmp, a) );
pR = &rtmp;
} else {
MP_CHECKOK( mp_copy(a, r) );
pR = r;
}
if (!q || q == a || q == b) {
MP_CHECKOK( mp_init_size(&qtmp, MP_USED(a), FLAG(a)) );
pQ = &qtmp;
} else {
MP_CHECKOK( s_mp_pad(q, MP_USED(a)) );
pQ = q;
mp_zero(pQ);
}
/*
If |a| <= |b|, we can compute the solution without division;
otherwise, we actually do the work required.
*/
if ((cmp = s_mp_cmp(a, b)) <= 0) {
if (cmp) {
/* r was set to a above. */
mp_zero(pQ);
} else {
mp_set(pQ, 1);
mp_zero(pR);
}
} else {
MP_CHECKOK( mp_init_copy(&btmp, b) );
MP_CHECKOK( s_mp_div(pR, &btmp, pQ) );
}
/* Compute the signs for the output */
MP_SIGN(pR) = signA; /* Sr = Sa */
/* Sq = ZPOS if Sa == Sb */ /* Sq = NEG if Sa != Sb */
MP_SIGN(pQ) = (signA == signB) ? ZPOS : NEG;
if(s_mp_cmp_d(pQ, 0) == MP_EQ)
SIGN(pQ) = ZPOS;
if(s_mp_cmp_d(pR, 0) == MP_EQ)
SIGN(pR) = ZPOS;
/* Copy output, if it is needed */
if(q && q != pQ)
s_mp_exch(pQ, q);
if(r && r != pR)
s_mp_exch(pR, r);
CLEANUP:
mp_clear(&btmp);
mp_clear(&rtmp);
mp_clear(&qtmp);
return res;
} /* end mp_div() */
/* }}} */
/* {{{ mp_div_2d(a, d, q, r) */
mp_err mp_div_2d(const mp_int *a, mp_digit d, mp_int *q, mp_int *r)
{
mp_err res;
ARGCHK(a != NULL, MP_BADARG);
if(q) {
if((res = mp_copy(a, q)) != MP_OKAY)
return res;
}
if(r) {
if((res = mp_copy(a, r)) != MP_OKAY)
return res;
}
if(q) {
s_mp_div_2d(q, d);
}
if(r) {
s_mp_mod_2d(r, d);
}
return MP_OKAY;
} /* end mp_div_2d() */
/* }}} */
/* {{{ mp_expt(a, b, c) */
/*
mp_expt(a, b, c)
Compute c = a ** b, that is, raise a to the b power. Uses a
standard iterative square-and-multiply technique.
*/
mp_err mp_expt(mp_int *a, mp_int *b, mp_int *c)
{
mp_int s, x;
mp_err res;
mp_digit d;
int dig, bit;
ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
if(mp_cmp_z(b) < 0)
return MP_RANGE;
if((res = mp_init(&s, FLAG(a))) != MP_OKAY)
return res;
mp_set(&s, 1);
if((res = mp_init_copy(&x, a)) != MP_OKAY)
goto X;
/* Loop over low-order digits in ascending order */
for(dig = 0; dig < (USED(b) - 1); dig++) {
d = DIGIT(b, dig);
/* Loop over bits of each non-maximal digit */
for(bit = 0; bit < DIGIT_BIT; bit++) {
if(d & 1) {
if((res = s_mp_mul(&s, &x)) != MP_OKAY)
goto CLEANUP;
}
d >>= 1;
if((res = s_mp_sqr(&x)) != MP_OKAY)
goto CLEANUP;
}
}
/* Consider now the last digit... */
d = DIGIT(b, dig);
while(d) {
if(d & 1) {
if((res = s_mp_mul(&s, &x)) != MP_OKAY)
goto CLEANUP;
}
d >>= 1;
if((res = s_mp_sqr(&x)) != MP_OKAY)
goto CLEANUP;
}
if(mp_iseven(b))
SIGN(&s) = SIGN(a);
res = mp_copy(&s, c);
CLEANUP:
mp_clear(&x);
X:
mp_clear(&s);
return res;
} /* end mp_expt() */
/* }}} */
/* {{{ mp_2expt(a, k) */
/* Compute a = 2^k */
mp_err mp_2expt(mp_int *a, mp_digit k)
{
ARGCHK(a != NULL, MP_BADARG);
return s_mp_2expt(a, k);
} /* end mp_2expt() */
/* }}} */
/* {{{ mp_mod(a, m, c) */
/*
mp_mod(a, m, c)
Compute c = a (mod m). Result will always be 0 <= c < m.
*/
mp_err mp_mod(const mp_int *a, const mp_int *m, mp_int *c)
{
mp_err res;
int mag;
ARGCHK(a != NULL && m != NULL && c != NULL, MP_BADARG);
if(SIGN(m) == NEG)
return MP_RANGE;
/*
If |a| > m, we need to divide to get the remainder and take the
absolute value.
If |a| < m, we don't need to do any division, just copy and adjust
the sign (if a is negative).
If |a| == m, we can simply set the result to zero.
This order is intended to minimize the average path length of the
comparison chain on common workloads -- the most frequent cases are
that |a| != m, so we do those first.
*/
if((mag = s_mp_cmp(a, m)) > 0) {
if((res = mp_div(a, m, NULL, c)) != MP_OKAY)
return res;
if(SIGN(c) == NEG) {
if((res = mp_add(c, m, c)) != MP_OKAY)
return res;
}
} else if(mag < 0) {
if((res = mp_copy(a, c)) != MP_OKAY)
return res;
if(mp_cmp_z(a) < 0) {
if((res = mp_add(c, m, c)) != MP_OKAY)
return res;
}
} else {
mp_zero(c);
}
return MP_OKAY;
} /* end mp_mod() */
/* }}} */
/* {{{ mp_mod_d(a, d, c) */
/*
mp_mod_d(a, d, c)
Compute c = a (mod d). Result will always be 0 <= c < d
*/
mp_err mp_mod_d(const mp_int *a, mp_digit d, mp_digit *c)
{
mp_err res;
mp_digit rem;
ARGCHK(a != NULL && c != NULL, MP_BADARG);
if(s_mp_cmp_d(a, d) > 0) {
if((res = mp_div_d(a, d, NULL, &rem)) != MP_OKAY)
return res;
} else {
if(SIGN(a) == NEG)
rem = d - DIGIT(a, 0);
else
rem = DIGIT(a, 0);
}
if(c)
*c = rem;
return MP_OKAY;
} /* end mp_mod_d() */
/* }}} */
/* {{{ mp_sqrt(a, b) */
/*
mp_sqrt(a, b)
Compute the integer square root of a, and store the result in b.
Uses an integer-arithmetic version of Newton's iterative linear
approximation technique to determine this value; the result has the
following two properties:
b^2 <= a
(b+1)^2 >= a
It is a range error to pass a negative value.
*/
mp_err mp_sqrt(const mp_int *a, mp_int *b)
{
mp_int x, t;
mp_err res;
mp_size used;
ARGCHK(a != NULL && b != NULL, MP_BADARG);
/* Cannot take square root of a negative value */
if(SIGN(a) == NEG)
return MP_RANGE;
/* Special cases for zero and one, trivial */
if(mp_cmp_d(a, 1) <= 0)
return mp_copy(a, b);
/* Initialize the temporaries we'll use below */
if((res = mp_init_size(&t, USED(a), FLAG(a))) != MP_OKAY)
return res;
/* Compute an initial guess for the iteration as a itself */
if((res = mp_init_copy(&x, a)) != MP_OKAY)
goto X;
used = MP_USED(&x);
if (used > 1) {
s_mp_rshd(&x, used / 2);
}
for(;;) {
/* t = (x * x) - a */
mp_copy(&x, &t); /* can't fail, t is big enough for original x */
if((res = mp_sqr(&t, &t)) != MP_OKAY ||
(res = mp_sub(&t, a, &t)) != MP_OKAY)
goto CLEANUP;
/* t = t / 2x */
s_mp_mul_2(&x);
if((res = mp_div(&t, &x, &t, NULL)) != MP_OKAY)
goto CLEANUP;
s_mp_div_2(&x);
/* Terminate the loop, if the quotient is zero */
if(mp_cmp_z(&t) == MP_EQ)
break;
/* x = x - t */
if((res = mp_sub(&x, &t, &x)) != MP_OKAY)
goto CLEANUP;
}
/* Copy result to output parameter */
mp_sub_d(&x, 1, &x);
s_mp_exch(&x, b);
CLEANUP:
mp_clear(&x);
X:
mp_clear(&t);
return res;
} /* end mp_sqrt() */
/* }}} */
/* }}} */
/*------------------------------------------------------------------------*/
/* {{{ Modular arithmetic */
#if MP_MODARITH
/* {{{ mp_addmod(a, b, m, c) */
/*
mp_addmod(a, b, m, c)
Compute c = (a + b) mod m
*/
mp_err mp_addmod(const mp_int *a, const mp_int *b, const mp_int *m, mp_int *c)
{
mp_err res;
ARGCHK(a != NULL && b != NULL && m != NULL && c != NULL, MP_BADARG);
if((res = mp_add(a, b, c)) != MP_OKAY)
return res;
if((res = mp_mod(c, m, c)) != MP_OKAY)
return res;
return MP_OKAY;
}
/* }}} */
/* {{{ mp_submod(a, b, m, c) */
/*
mp_submod(a, b, m, c)
Compute c = (a - b) mod m
*/
mp_err mp_submod(const mp_int *a, const mp_int *b, const mp_int *m, mp_int *c)
{
mp_err res;
ARGCHK(a != NULL && b != NULL && m != NULL && c != NULL, MP_BADARG);
if((res = mp_sub(a, b, c)) != MP_OKAY)
return res;
if((res = mp_mod(c, m, c)) != MP_OKAY)
return res;
return MP_OKAY;
}
/* }}} */
/* {{{ mp_mulmod(a, b, m, c) */
/*
mp_mulmod(a, b, m, c)
Compute c = (a * b) mod m
*/
mp_err mp_mulmod(const mp_int *a, const mp_int *b, const mp_int *m, mp_int *c)
{
mp_err res;
ARGCHK(a != NULL && b != NULL && m != NULL && c != NULL, MP_BADARG);
if((res = mp_mul(a, b, c)) != MP_OKAY)
return res;
if((res = mp_mod(c, m, c)) != MP_OKAY)
return res;
return MP_OKAY;
}
/* }}} */
/* {{{ mp_sqrmod(a, m, c) */
#if MP_SQUARE
mp_err mp_sqrmod(const mp_int *a, const mp_int *m, mp_int *c)
{
mp_err res;
ARGCHK(a != NULL && m != NULL && c != NULL, MP_BADARG);
if((res = mp_sqr(a, c)) != MP_OKAY)
return res;
if((res = mp_mod(c, m, c)) != MP_OKAY)
return res;
return MP_OKAY;
} /* end mp_sqrmod() */
#endif
/* }}} */
/* {{{ s_mp_exptmod(a, b, m, c) */
/*
s_mp_exptmod(a, b, m, c)
Compute c = (a ** b) mod m. Uses a standard square-and-multiply
method with modular reductions at each step. (This is basically the
same code as mp_expt(), except for the addition of the reductions)
The modular reductions are done using Barrett's algorithm (see
s_mp_reduce() below for details)
*/
mp_err s_mp_exptmod(const mp_int *a, const mp_int *b, const mp_int *m, mp_int *c)
{
mp_int s, x, mu;
mp_err res;
mp_digit d;
int dig, bit;
ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
if(mp_cmp_z(b) < 0 || mp_cmp_z(m) <= 0)
return MP_RANGE;
if((res = mp_init(&s, FLAG(a))) != MP_OKAY)
return res;
if((res = mp_init_copy(&x, a)) != MP_OKAY ||
(res = mp_mod(&x, m, &x)) != MP_OKAY)
goto X;
if((res = mp_init(&mu, FLAG(a))) != MP_OKAY)
goto MU;
mp_set(&s, 1);
/* mu = b^2k / m */
s_mp_add_d(&mu, 1);
s_mp_lshd(&mu, 2 * USED(m));
if((res = mp_div(&mu, m, &mu, NULL)) != MP_OKAY)
goto CLEANUP;
/* Loop over digits of b in ascending order, except highest order */
for(dig = 0; dig < (USED(b) - 1); dig++) {
d = DIGIT(b, dig);
/* Loop over the bits of the lower-order digits */
for(bit = 0; bit < DIGIT_BIT; bit++) {
if(d & 1) {
if((res = s_mp_mul(&s, &x)) != MP_OKAY)
goto CLEANUP;
if((res = s_mp_reduce(&s, m, &mu)) != MP_OKAY)
goto CLEANUP;
}
d >>= 1;
if((res = s_mp_sqr(&x)) != MP_OKAY)
goto CLEANUP;
if((res = s_mp_reduce(&x, m, &mu)) != MP_OKAY)
goto CLEANUP;
}
}
/* Now do the last digit... */
d = DIGIT(b, dig);
while(d) {
if(d & 1) {
if((res = s_mp_mul(&s, &x)) != MP_OKAY)
goto CLEANUP;
if((res = s_mp_reduce(&s, m, &mu)) != MP_OKAY)
goto CLEANUP;
}
d >>= 1;
if((res = s_mp_sqr(&x)) != MP_OKAY)
goto CLEANUP;
if((res = s_mp_reduce(&x, m, &mu)) != MP_OKAY)
goto CLEANUP;
}
s_mp_exch(&s, c);
CLEANUP:
mp_clear(&mu);
MU:
mp_clear(&x);
X:
mp_clear(&s);
return res;
} /* end s_mp_exptmod() */
/* }}} */
/* {{{ mp_exptmod_d(a, d, m, c) */
mp_err mp_exptmod_d(const mp_int *a, mp_digit d, const mp_int *m, mp_int *c)
{
mp_int s, x;
mp_err res;
ARGCHK(a != NULL && c != NULL, MP_BADARG);
if((res = mp_init(&s, FLAG(a))) != MP_OKAY)
return res;
if((res = mp_init_copy(&x, a)) != MP_OKAY)
goto X;
mp_set(&s, 1);
while(d != 0) {
if(d & 1) {
if((res = s_mp_mul(&s, &x)) != MP_OKAY ||
(res = mp_mod(&s, m, &s)) != MP_OKAY)
goto CLEANUP;
}
d /= 2;
if((res = s_mp_sqr(&x)) != MP_OKAY ||
(res = mp_mod(&x, m, &x)) != MP_OKAY)
goto CLEANUP;
}
s_mp_exch(&s, c);
CLEANUP:
mp_clear(&x);
X:
mp_clear(&s);
return res;
} /* end mp_exptmod_d() */
/* }}} */
#endif /* if MP_MODARITH */
/* }}} */
/*------------------------------------------------------------------------*/
/* {{{ Comparison functions */
/* {{{ mp_cmp_z(a) */
/*
mp_cmp_z(a)
Compare a <=> 0. Returns <0 if a<0, 0 if a=0, >0 if a>0.
*/
int mp_cmp_z(const mp_int *a)
{
if(SIGN(a) == NEG)
return MP_LT;
else if(USED(a) == 1 && DIGIT(a, 0) == 0)
return MP_EQ;
else
return MP_GT;
} /* end mp_cmp_z() */
/* }}} */
/* {{{ mp_cmp_d(a, d) */
/*
mp_cmp_d(a, d)
Compare a <=> d. Returns <0 if a<d, 0 if a=d, >0 if a>d
*/
int mp_cmp_d(const mp_int *a, mp_digit d)
{
ARGCHK(a != NULL, MP_EQ);
if(SIGN(a) == NEG)
return MP_LT;
return s_mp_cmp_d(a, d);
} /* end mp_cmp_d() */
/* }}} */
/* {{{ mp_cmp(a, b) */
int mp_cmp(const mp_int *a, const mp_int *b)
{
ARGCHK(a != NULL && b != NULL, MP_EQ);
if(SIGN(a) == SIGN(b)) {
int mag;
if((mag = s_mp_cmp(a, b)) == MP_EQ)
return MP_EQ;
if(SIGN(a) == ZPOS)
return mag;
else
return -mag;
} else if(SIGN(a) == ZPOS) {
return MP_GT;
} else {
return MP_LT;
}
} /* end mp_cmp() */
/* }}} */
/* {{{ mp_cmp_mag(a, b) */
/*
mp_cmp_mag(a, b)
Compares |a| <=> |b|, and returns an appropriate comparison result
*/
int mp_cmp_mag(mp_int *a, mp_int *b)
{
ARGCHK(a != NULL && b != NULL, MP_EQ);
return s_mp_cmp(a, b);
} /* end mp_cmp_mag() */
/* }}} */
/* {{{ mp_cmp_int(a, z, kmflag) */
/*
This just converts z to an mp_int, and uses the existing comparison
routines. This is sort of inefficient, but it's not clear to me how
frequently this wil get used anyway. For small positive constants,
you can always use mp_cmp_d(), and for zero, there is mp_cmp_z().
*/
int mp_cmp_int(const mp_int *a, long z, int kmflag)
{
mp_int tmp;
int out;
ARGCHK(a != NULL, MP_EQ);
mp_init(&tmp, kmflag); mp_set_int(&tmp, z);
out = mp_cmp(a, &tmp);
mp_clear(&tmp);
return out;
} /* end mp_cmp_int() */
/* }}} */
/* {{{ mp_isodd(a) */
/*
mp_isodd(a)
Returns a true (non-zero) value if a is odd, false (zero) otherwise.
*/
int mp_isodd(const mp_int *a)
{
ARGCHK(a != NULL, 0);
return (int)(DIGIT(a, 0) & 1);
} /* end mp_isodd() */
/* }}} */
/* {{{ mp_iseven(a) */
int mp_iseven(const mp_int *a)
{
return !mp_isodd(a);
} /* end mp_iseven() */
/* }}} */
/* }}} */
/*------------------------------------------------------------------------*/
/* {{{ Number theoretic functions */
#if MP_NUMTH
/* {{{ mp_gcd(a, b, c) */
/*
Like the old mp_gcd() function, except computes the GCD using the
binary algorithm due to Josef Stein in 1961 (via Knuth).
*/
mp_err mp_gcd(mp_int *a, mp_int *b, mp_int *c)
{
mp_err res;
mp_int u, v, t;
mp_size k = 0;
ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
if(mp_cmp_z(a) == MP_EQ && mp_cmp_z(b) == MP_EQ)
return MP_RANGE;
if(mp_cmp_z(a) == MP_EQ) {
return mp_copy(b, c);
} else if(mp_cmp_z(b) == MP_EQ) {
return mp_copy(a, c);
}
if((res = mp_init(&t, FLAG(a))) != MP_OKAY)
return res;
if((res = mp_init_copy(&u, a)) != MP_OKAY)
goto U;
if((res = mp_init_copy(&v, b)) != MP_OKAY)
goto V;
SIGN(&u) = ZPOS;
SIGN(&v) = ZPOS;
/* Divide out common factors of 2 until at least 1 of a, b is even */
while(mp_iseven(&u) && mp_iseven(&v)) {
s_mp_div_2(&u);
s_mp_div_2(&v);
++k;
}
/* Initialize t */
if(mp_isodd(&u)) {
if((res = mp_copy(&v, &t)) != MP_OKAY)
goto CLEANUP;
/* t = -v */
if(SIGN(&v) == ZPOS)
SIGN(&t) = NEG;
else
SIGN(&t) = ZPOS;
} else {
if((res = mp_copy(&u, &t)) != MP_OKAY)
goto CLEANUP;
}
for(;;) {
while(mp_iseven(&t)) {
s_mp_div_2(&t);
}
if(mp_cmp_z(&t) == MP_GT) {
if((res = mp_copy(&t, &u)) != MP_OKAY)
goto CLEANUP;
} else {
if((res = mp_copy(&t, &v)) != MP_OKAY)
goto CLEANUP;
/* v = -t */
if(SIGN(&t) == ZPOS)
SIGN(&v) = NEG;
else
SIGN(&v) = ZPOS;
}
if((res = mp_sub(&u, &v, &t)) != MP_OKAY)
goto CLEANUP;
if(s_mp_cmp_d(&t, 0) == MP_EQ)
break;
}
s_mp_2expt(&v, k); /* v = 2^k */
res = mp_mul(&u, &v, c); /* c = u * v */
CLEANUP:
mp_clear(&v);
V:
mp_clear(&u);
U:
mp_clear(&t);
return res;
} /* end mp_gcd() */
/* }}} */
/* {{{ mp_lcm(a, b, c) */
/* We compute the least common multiple using the rule:
ab = [a, b](a, b)
... by computing the product, and dividing out the gcd.
*/
mp_err mp_lcm(mp_int *a, mp_int *b, mp_int *c)
{
mp_int gcd, prod;
mp_err res;
ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
/* Set up temporaries */
if((res = mp_init(&gcd, FLAG(a))) != MP_OKAY)
return res;
if((res = mp_init(&prod, FLAG(a))) != MP_OKAY)
goto GCD;
if((res = mp_mul(a, b, &prod)) != MP_OKAY)
goto CLEANUP;
if((res = mp_gcd(a, b, &gcd)) != MP_OKAY)
goto CLEANUP;
res = mp_div(&prod, &gcd, c, NULL);
CLEANUP:
mp_clear(&prod);
GCD:
mp_clear(&gcd);
return res;
} /* end mp_lcm() */
/* }}} */
/* {{{ mp_xgcd(a, b, g, x, y) */
/*
mp_xgcd(a, b, g, x, y)
Compute g = (a, b) and values x and y satisfying Bezout's identity
(that is, ax + by = g). This uses the binary extended GCD algorithm
based on the Stein algorithm used for mp_gcd()
See algorithm 14.61 in Handbook of Applied Cryptogrpahy.
*/
mp_err mp_xgcd(const mp_int *a, const mp_int *b, mp_int *g, mp_int *x, mp_int *y)
{
mp_int gx, xc, yc, u, v, A, B, C, D;
mp_int *clean[9];
mp_err res;
int last = -1;
if(mp_cmp_z(b) == 0)
return MP_RANGE;
/* Initialize all these variables we need */
MP_CHECKOK( mp_init(&u, FLAG(a)) );
clean[++last] = &u;
MP_CHECKOK( mp_init(&v, FLAG(a)) );
clean[++last] = &v;
MP_CHECKOK( mp_init(&gx, FLAG(a)) );
clean[++last] = &gx;
MP_CHECKOK( mp_init(&A, FLAG(a)) );
clean[++last] = &A;
MP_CHECKOK( mp_init(&B, FLAG(a)) );
clean[++last] = &B;
MP_CHECKOK( mp_init(&C, FLAG(a)) );
clean[++last] = &C;
MP_CHECKOK( mp_init(&D, FLAG(a)) );
clean[++last] = &D;
MP_CHECKOK( mp_init_copy(&xc, a) );
clean[++last] = &xc;
mp_abs(&xc, &xc);
MP_CHECKOK( mp_init_copy(&yc, b) );
clean[++last] = &yc;
mp_abs(&yc, &yc);
mp_set(&gx, 1);
/* Divide by two until at least one of them is odd */
while(mp_iseven(&xc) && mp_iseven(&yc)) {
mp_size nx = mp_trailing_zeros(&xc);
mp_size ny = mp_trailing_zeros(&yc);
mp_size n = MP_MIN(nx, ny);
s_mp_div_2d(&xc,n);
s_mp_div_2d(&yc,n);
MP_CHECKOK( s_mp_mul_2d(&gx,n) );
}
mp_copy(&xc, &u);
mp_copy(&yc, &v);
mp_set(&A, 1); mp_set(&D, 1);
/* Loop through binary GCD algorithm */
do {
while(mp_iseven(&u)) {
s_mp_div_2(&u);
if(mp_iseven(&A) && mp_iseven(&B)) {
s_mp_div_2(&A); s_mp_div_2(&B);
} else {
MP_CHECKOK( mp_add(&A, &yc, &A) );
s_mp_div_2(&A);
MP_CHECKOK( mp_sub(&B, &xc, &B) );
s_mp_div_2(&B);
}
}
while(mp_iseven(&v)) {
s_mp_div_2(&v);
if(mp_iseven(&C) && mp_iseven(&D)) {
s_mp_div_2(&C); s_mp_div_2(&D);
} else {
MP_CHECKOK( mp_add(&C, &yc, &C) );
s_mp_div_2(&C);
MP_CHECKOK( mp_sub(&D, &xc, &D) );
s_mp_div_2(&D);
}
}
if(mp_cmp(&u, &v) >= 0) {
MP_CHECKOK( mp_sub(&u, &v, &u) );
MP_CHECKOK( mp_sub(&A, &C, &A) );
MP_CHECKOK( mp_sub(&B, &D, &B) );
} else {
MP_CHECKOK( mp_sub(&v, &u, &v) );
MP_CHECKOK( mp_sub(&C, &A, &C) );
MP_CHECKOK( mp_sub(&D, &B, &D) );
}
} while (mp_cmp_z(&u) != 0);
/* copy results to output */
if(x)
MP_CHECKOK( mp_copy(&C, x) );
if(y)
MP_CHECKOK( mp_copy(&D, y) );
if(g)
MP_CHECKOK( mp_mul(&gx, &v, g) );
CLEANUP:
while(last >= 0)
mp_clear(clean[last--]);
return res;
} /* end mp_xgcd() */
/* }}} */
mp_size mp_trailing_zeros(const mp_int *mp)
{
mp_digit d;
mp_size n = 0;
int ix;
if (!mp || !MP_DIGITS(mp) || !mp_cmp_z(mp))
return n;
for (ix = 0; !(d = MP_DIGIT(mp,ix)) && (ix < MP_USED(mp)); ++ix)
n += MP_DIGIT_BIT;
if (!d)
return 0; /* shouldn't happen, but ... */
#if !defined(MP_USE_UINT_DIGIT)
if (!(d & 0xffffffffU)) {
d >>= 32;
n += 32;
}
#endif
if (!(d & 0xffffU)) {
d >>= 16;
n += 16;
}
if (!(d & 0xffU)) {
d >>= 8;
n += 8;
}
if (!(d & 0xfU)) {
d >>= 4;
n += 4;
}
if (!(d & 0x3U)) {
d >>= 2;
n += 2;
}
if (!(d & 0x1U)) {
d >>= 1;
n += 1;
}
#if MP_ARGCHK == 2
assert(0 != (d & 1));
#endif
return n;
}
/* Given a and prime p, computes c and k such that a*c == 2**k (mod p).
** Returns k (positive) or error (negative).
** This technique from the paper "Fast Modular Reciprocals" (unpublished)
** by Richard Schroeppel (a.k.a. Captain Nemo).
*/
mp_err s_mp_almost_inverse(const mp_int *a, const mp_int *p, mp_int *c)
{
mp_err res;
mp_err k = 0;
mp_int d, f, g;
ARGCHK(a && p && c, MP_BADARG);
MP_DIGITS(&d) = 0;
MP_DIGITS(&f) = 0;
MP_DIGITS(&g) = 0;
MP_CHECKOK( mp_init(&d, FLAG(a)) );
MP_CHECKOK( mp_init_copy(&f, a) ); /* f = a */
MP_CHECKOK( mp_init_copy(&g, p) ); /* g = p */
mp_set(c, 1);
mp_zero(&d);
if (mp_cmp_z(&f) == 0) {
res = MP_UNDEF;
} else
for (;;) {
int diff_sign;
while (mp_iseven(&f)) {
mp_size n = mp_trailing_zeros(&f);
if (!n) {
res = MP_UNDEF;
goto CLEANUP;
}
s_mp_div_2d(&f, n);
MP_CHECKOK( s_mp_mul_2d(&d, n) );
k += n;
}
if (mp_cmp_d(&f, 1) == MP_EQ) { /* f == 1 */
res = k;
break;
}
diff_sign = mp_cmp(&f, &g);
if (diff_sign < 0) { /* f < g */
s_mp_exch(&f, &g);
s_mp_exch(c, &d);
} else if (diff_sign == 0) { /* f == g */
res = MP_UNDEF; /* a and p are not relatively prime */
break;
}
if ((MP_DIGIT(&f,0) % 4) == (MP_DIGIT(&g,0) % 4)) {
MP_CHECKOK( mp_sub(&f, &g, &f) ); /* f = f - g */
MP_CHECKOK( mp_sub(c, &d, c) ); /* c = c - d */
} else {
MP_CHECKOK( mp_add(&f, &g, &f) ); /* f = f + g */
MP_CHECKOK( mp_add(c, &d, c) ); /* c = c + d */
}
}
if (res >= 0) {
while (MP_SIGN(c) != MP_ZPOS) {
MP_CHECKOK( mp_add(c, p, c) );
}
res = k;
}
CLEANUP:
mp_clear(&d);
mp_clear(&f);
mp_clear(&g);
return res;
}
/* Compute T = (P ** -1) mod MP_RADIX. Also works for 16-bit mp_digits.
** This technique from the paper "Fast Modular Reciprocals" (unpublished)
** by Richard Schroeppel (a.k.a. Captain Nemo).
*/
mp_digit s_mp_invmod_radix(mp_digit P)
{
mp_digit T = P;
T *= 2 - (P * T);
T *= 2 - (P * T);
T *= 2 - (P * T);
T *= 2 - (P * T);
#if !defined(MP_USE_UINT_DIGIT)
T *= 2 - (P * T);
T *= 2 - (P * T);
#endif
return T;
}
/* Given c, k, and prime p, where a*c == 2**k (mod p),
** Compute x = (a ** -1) mod p. This is similar to Montgomery reduction.
** This technique from the paper "Fast Modular Reciprocals" (unpublished)
** by Richard Schroeppel (a.k.a. Captain Nemo).
*/
mp_err s_mp_fixup_reciprocal(const mp_int *c, const mp_int *p, int k, mp_int *x)
{
int k_orig = k;
mp_digit r;
mp_size ix;
mp_err res;
if (mp_cmp_z(c) < 0) { /* c < 0 */
MP_CHECKOK( mp_add(c, p, x) ); /* x = c + p */
} else {
MP_CHECKOK( mp_copy(c, x) ); /* x = c */
}
/* make sure x is large enough */
ix = MP_HOWMANY(k, MP_DIGIT_BIT) + MP_USED(p) + 1;
ix = MP_MAX(ix, MP_USED(x));
MP_CHECKOK( s_mp_pad(x, ix) );
r = 0 - s_mp_invmod_radix(MP_DIGIT(p,0));
for (ix = 0; k > 0; ix++) {
int j = MP_MIN(k, MP_DIGIT_BIT);
mp_digit v = r * MP_DIGIT(x, ix);
if (j < MP_DIGIT_BIT) {
v &= ((mp_digit)1 << j) - 1; /* v = v mod (2 ** j) */
}
s_mp_mul_d_add_offset(p, v, x, ix); /* x += p * v * (RADIX ** ix) */
k -= j;
}
s_mp_clamp(x);
s_mp_div_2d(x, k_orig);
res = MP_OKAY;
CLEANUP:
return res;
}
/* compute mod inverse using Schroeppel's method, only if m is odd */
mp_err s_mp_invmod_odd_m(const mp_int *a, const mp_int *m, mp_int *c)
{
int k;
mp_err res;
mp_int x;
ARGCHK(a && m && c, MP_BADARG);
if(mp_cmp_z(a) == 0 || mp_cmp_z(m) == 0)
return MP_RANGE;
if (mp_iseven(m))
return MP_UNDEF;
MP_DIGITS(&x) = 0;
if (a == c) {
if ((res = mp_init_copy(&x, a)) != MP_OKAY)
return res;
if (a == m)
m = &x;
a = &x;
} else if (m == c) {
if ((res = mp_init_copy(&x, m)) != MP_OKAY)
return res;
m = &x;
} else {
MP_DIGITS(&x) = 0;
}
MP_CHECKOK( s_mp_almost_inverse(a, m, c) );
k = res;
MP_CHECKOK( s_mp_fixup_reciprocal(c, m, k, c) );
CLEANUP:
mp_clear(&x);
return res;
}
/* Known good algorithm for computing modular inverse. But slow. */
mp_err mp_invmod_xgcd(const mp_int *a, const mp_int *m, mp_int *c)
{
mp_int g, x;
mp_err res;
ARGCHK(a && m && c, MP_BADARG);
if(mp_cmp_z(a) == 0 || mp_cmp_z(m) == 0)
return MP_RANGE;
MP_DIGITS(&g) = 0;
MP_DIGITS(&x) = 0;
MP_CHECKOK( mp_init(&x, FLAG(a)) );
MP_CHECKOK( mp_init(&g, FLAG(a)) );
MP_CHECKOK( mp_xgcd(a, m, &g, &x, NULL) );
if (mp_cmp_d(&g, 1) != MP_EQ) {
res = MP_UNDEF;
goto CLEANUP;
}
res = mp_mod(&x, m, c);
SIGN(c) = SIGN(a);
CLEANUP:
mp_clear(&x);
mp_clear(&g);
return res;
}
/* modular inverse where modulus is 2**k. */
/* c = a**-1 mod 2**k */
mp_err s_mp_invmod_2d(const mp_int *a, mp_size k, mp_int *c)
{
mp_err res;
mp_size ix = k + 4;
mp_int t0, t1, val, tmp, two2k;
static const mp_digit d2 = 2;
static const mp_int two = { 0, MP_ZPOS, 1, 1, (mp_digit *)&d2 };
if (mp_iseven(a))
return MP_UNDEF;
if (k <= MP_DIGIT_BIT) {
mp_digit i = s_mp_invmod_radix(MP_DIGIT(a,0));
if (k < MP_DIGIT_BIT)
i &= ((mp_digit)1 << k) - (mp_digit)1;
mp_set(c, i);
return MP_OKAY;
}
MP_DIGITS(&t0) = 0;
MP_DIGITS(&t1) = 0;
MP_DIGITS(&val) = 0;
MP_DIGITS(&tmp) = 0;
MP_DIGITS(&two2k) = 0;
MP_CHECKOK( mp_init_copy(&val, a) );
s_mp_mod_2d(&val, k);
MP_CHECKOK( mp_init_copy(&t0, &val) );
MP_CHECKOK( mp_init_copy(&t1, &t0) );
MP_CHECKOK( mp_init(&tmp, FLAG(a)) );
MP_CHECKOK( mp_init(&two2k, FLAG(a)) );
MP_CHECKOK( s_mp_2expt(&two2k, k) );
do {
MP_CHECKOK( mp_mul(&val, &t1, &tmp) );
MP_CHECKOK( mp_sub(&two, &tmp, &tmp) );
MP_CHECKOK( mp_mul(&t1, &tmp, &t1) );
s_mp_mod_2d(&t1, k);
while (MP_SIGN(&t1) != MP_ZPOS) {
MP_CHECKOK( mp_add(&t1, &two2k, &t1) );
}
if (mp_cmp(&t1, &t0) == MP_EQ)
break;
MP_CHECKOK( mp_copy(&t1, &t0) );
} while (--ix > 0);
if (!ix) {
res = MP_UNDEF;
} else {
mp_exch(c, &t1);
}
CLEANUP:
mp_clear(&t0);
mp_clear(&t1);
mp_clear(&val);
mp_clear(&tmp);
mp_clear(&two2k);
return res;
}
mp_err s_mp_invmod_even_m(const mp_int *a, const mp_int *m, mp_int *c)
{
mp_err res;
mp_size k;
mp_int oddFactor, evenFactor; /* factors of the modulus */
mp_int oddPart, evenPart; /* parts to combine via CRT. */
mp_int C2, tmp1, tmp2;
/*static const mp_digit d1 = 1; */
/*static const mp_int one = { MP_ZPOS, 1, 1, (mp_digit *)&d1 }; */
if ((res = s_mp_ispow2(m)) >= 0) {
k = res;
return s_mp_invmod_2d(a, k, c);
}
MP_DIGITS(&oddFactor) = 0;
MP_DIGITS(&evenFactor) = 0;
MP_DIGITS(&oddPart) = 0;
MP_DIGITS(&evenPart) = 0;
MP_DIGITS(&C2) = 0;
MP_DIGITS(&tmp1) = 0;
MP_DIGITS(&tmp2) = 0;
MP_CHECKOK( mp_init_copy(&oddFactor, m) ); /* oddFactor = m */
MP_CHECKOK( mp_init(&evenFactor, FLAG(m)) );
MP_CHECKOK( mp_init(&oddPart, FLAG(m)) );
MP_CHECKOK( mp_init(&evenPart, FLAG(m)) );
MP_CHECKOK( mp_init(&C2, FLAG(m)) );
MP_CHECKOK( mp_init(&tmp1, FLAG(m)) );
MP_CHECKOK( mp_init(&tmp2, FLAG(m)) );
k = mp_trailing_zeros(m);
s_mp_div_2d(&oddFactor, k);
MP_CHECKOK( s_mp_2expt(&evenFactor, k) );
/* compute a**-1 mod oddFactor. */
MP_CHECKOK( s_mp_invmod_odd_m(a, &oddFactor, &oddPart) );
/* compute a**-1 mod evenFactor, where evenFactor == 2**k. */
MP_CHECKOK( s_mp_invmod_2d( a, k, &evenPart) );
/* Use Chinese Remainer theorem to compute a**-1 mod m. */
/* let m1 = oddFactor, v1 = oddPart,
* let m2 = evenFactor, v2 = evenPart.
*/
/* Compute C2 = m1**-1 mod m2. */
MP_CHECKOK( s_mp_invmod_2d(&oddFactor, k, &C2) );
/* compute u = (v2 - v1)*C2 mod m2 */
MP_CHECKOK( mp_sub(&evenPart, &oddPart, &tmp1) );
MP_CHECKOK( mp_mul(&tmp1, &C2, &tmp2) );
s_mp_mod_2d(&tmp2, k);
while (MP_SIGN(&tmp2) != MP_ZPOS) {
MP_CHECKOK( mp_add(&tmp2, &evenFactor, &tmp2) );
}
/* compute answer = v1 + u*m1 */
MP_CHECKOK( mp_mul(&tmp2, &oddFactor, c) );
MP_CHECKOK( mp_add(&oddPart, c, c) );
/* not sure this is necessary, but it's low cost if not. */
MP_CHECKOK( mp_mod(c, m, c) );
CLEANUP:
mp_clear(&oddFactor);
mp_clear(&evenFactor);
mp_clear(&oddPart);
mp_clear(&evenPart);
mp_clear(&C2);
mp_clear(&tmp1);
mp_clear(&tmp2);
return res;
}
/* {{{ mp_invmod(a, m, c) */
/*
mp_invmod(a, m, c)
Compute c = a^-1 (mod m), if there is an inverse for a (mod m).
This is equivalent to the question of whether (a, m) = 1. If not,
MP_UNDEF is returned, and there is no inverse.
*/
mp_err mp_invmod(const mp_int *a, const mp_int *m, mp_int *c)
{
ARGCHK(a && m && c, MP_BADARG);
if(mp_cmp_z(a) == 0 || mp_cmp_z(m) == 0)
return MP_RANGE;
if (mp_isodd(m)) {
return s_mp_invmod_odd_m(a, m, c);
}
if (mp_iseven(a))
return MP_UNDEF; /* not invertable */
return s_mp_invmod_even_m(a, m, c);
} /* end mp_invmod() */
/* }}} */
#endif /* if MP_NUMTH */
/* }}} */
/*------------------------------------------------------------------------*/
/* {{{ mp_print(mp, ofp) */
#if MP_IOFUNC
/*
mp_print(mp, ofp)
Print a textual representation of the given mp_int on the output
stream 'ofp'. Output is generated using the internal radix.
*/
void mp_print(mp_int *mp, FILE *ofp)
{
int ix;
if(mp == NULL || ofp == NULL)
return;
fputc((SIGN(mp) == NEG) ? '-' : '+', ofp);
for(ix = USED(mp) - 1; ix >= 0; ix--) {
fprintf(ofp, DIGIT_FMT, DIGIT(mp, ix));
}
} /* end mp_print() */
#endif /* if MP_IOFUNC */
/* }}} */
/*------------------------------------------------------------------------*/
/* {{{ More I/O Functions */
/* {{{ mp_read_raw(mp, str, len) */
/*
mp_read_raw(mp, str, len)
Read in a raw value (base 256) into the given mp_int
*/
mp_err mp_read_raw(mp_int *mp, char *str, int len)
{
int ix;
mp_err res;
unsigned char *ustr = (unsigned char *)str;
ARGCHK(mp != NULL && str != NULL && len > 0, MP_BADARG);
mp_zero(mp);
/* Get sign from first byte */
if(ustr[0])
SIGN(mp) = NEG;
else
SIGN(mp) = ZPOS;
/* Read the rest of the digits */
for(ix = 1; ix < len; ix++) {
if((res = mp_mul_d(mp, 256, mp)) != MP_OKAY)
return res;
if((res = mp_add_d(mp, ustr[ix], mp)) != MP_OKAY)
return res;
}
return MP_OKAY;
} /* end mp_read_raw() */
/* }}} */
/* {{{ mp_raw_size(mp) */
int mp_raw_size(mp_int *mp)
{
ARGCHK(mp != NULL, 0);
return (USED(mp) * sizeof(mp_digit)) + 1;
} /* end mp_raw_size() */
/* }}} */
/* {{{ mp_toraw(mp, str) */
mp_err mp_toraw(mp_int *mp, char *str)
{
int ix, jx, pos = 1;
ARGCHK(mp != NULL && str != NULL, MP_BADARG);
str[0] = (char)SIGN(mp);
/* Iterate over each digit... */
for(ix = USED(mp) - 1; ix >= 0; ix--) {
mp_digit d = DIGIT(mp, ix);
/* Unpack digit bytes, high order first */
for(jx = sizeof(mp_digit) - 1; jx >= 0; jx--) {
str[pos++] = (char)(d >> (jx * CHAR_BIT));
}
}
return MP_OKAY;
} /* end mp_toraw() */
/* }}} */
/* {{{ mp_read_radix(mp, str, radix) */
/*
mp_read_radix(mp, str, radix)
Read an integer from the given string, and set mp to the resulting
value. The input is presumed to be in base 10. Leading non-digit
characters are ignored, and the function reads until a non-digit
character or the end of the string.
*/
mp_err mp_read_radix(mp_int *mp, const char *str, int radix)
{
int ix = 0, val = 0;
mp_err res;
mp_sign sig = ZPOS;
ARGCHK(mp != NULL && str != NULL && radix >= 2 && radix <= MAX_RADIX,
MP_BADARG);
mp_zero(mp);
/* Skip leading non-digit characters until a digit or '-' or '+' */
while(str[ix] &&
(s_mp_tovalue(str[ix], radix) < 0) &&
str[ix] != '-' &&
str[ix] != '+') {
++ix;
}
if(str[ix] == '-') {
sig = NEG;
++ix;
} else if(str[ix] == '+') {
sig = ZPOS; /* this is the default anyway... */
++ix;
}
while((val = s_mp_tovalue(str[ix], radix)) >= 0) {
if((res = s_mp_mul_d(mp, radix)) != MP_OKAY)
return res;
if((res = s_mp_add_d(mp, val)) != MP_OKAY)
return res;
++ix;
}
if(s_mp_cmp_d(mp, 0) == MP_EQ)
SIGN(mp) = ZPOS;
else
SIGN(mp) = sig;
return MP_OKAY;
} /* end mp_read_radix() */
mp_err mp_read_variable_radix(mp_int *a, const char * str, int default_radix)
{
int radix = default_radix;
int cx;
mp_sign sig = ZPOS;
mp_err res;
/* Skip leading non-digit characters until a digit or '-' or '+' */
while ((cx = *str) != 0 &&
(s_mp_tovalue(cx, radix) < 0) &&
cx != '-' &&
cx != '+') {
++str;
}
if (cx == '-') {
sig = NEG;
++str;
} else if (cx == '+') {
sig = ZPOS; /* this is the default anyway... */
++str;
}
if (str[0] == '0') {
if ((str[1] | 0x20) == 'x') {
radix = 16;
str += 2;
} else {
radix = 8;
str++;
}
}
res = mp_read_radix(a, str, radix);
if (res == MP_OKAY) {
MP_SIGN(a) = (s_mp_cmp_d(a, 0) == MP_EQ) ? ZPOS : sig;
}
return res;
}
/* }}} */
/* {{{ mp_radix_size(mp, radix) */
int mp_radix_size(mp_int *mp, int radix)
{
int bits;
if(!mp || radix < 2 || radix > MAX_RADIX)
return 0;
bits = USED(mp) * DIGIT_BIT - 1;
return s_mp_outlen(bits, radix);
} /* end mp_radix_size() */
/* }}} */
/* {{{ mp_toradix(mp, str, radix) */
mp_err mp_toradix(mp_int *mp, char *str, int radix)
{
int ix, pos = 0;
ARGCHK(mp != NULL && str != NULL, MP_BADARG);
ARGCHK(radix > 1 && radix <= MAX_RADIX, MP_RANGE);
if(mp_cmp_z(mp) == MP_EQ) {
str[0] = '0';
str[1] = '\0';
} else {
mp_err res;
mp_int tmp;
mp_sign sgn;
mp_digit rem, rdx = (mp_digit)radix;
char ch;
if((res = mp_init_copy(&tmp, mp)) != MP_OKAY)
return res;
/* Save sign for later, and take absolute value */
sgn = SIGN(&tmp); SIGN(&tmp) = ZPOS;
/* Generate output digits in reverse order */
while(mp_cmp_z(&tmp) != 0) {
if((res = mp_div_d(&tmp, rdx, &tmp, &rem)) != MP_OKAY) {
mp_clear(&tmp);
return res;
}
/* Generate digits, use capital letters */
ch = s_mp_todigit(rem, radix, 0);
str[pos++] = ch;
}
/* Add - sign if original value was negative */
if(sgn == NEG)
str[pos++] = '-';
/* Add trailing NUL to end the string */
str[pos--] = '\0';
/* Reverse the digits and sign indicator */
ix = 0;
while(ix < pos) {
char tmp = str[ix];
str[ix] = str[pos];
str[pos] = tmp;
++ix;
--pos;
}
mp_clear(&tmp);
}
return MP_OKAY;
} /* end mp_toradix() */
/* }}} */
/* {{{ mp_tovalue(ch, r) */
int mp_tovalue(char ch, int r)
{
return s_mp_tovalue(ch, r);
} /* end mp_tovalue() */
/* }}} */
/* }}} */
/* {{{ mp_strerror(ec) */
/*
mp_strerror(ec)
Return a string describing the meaning of error code 'ec'. The
string returned is allocated in static memory, so the caller should
not attempt to modify or free the memory associated with this
string.
*/
const char *mp_strerror(mp_err ec)
{
int aec = (ec < 0) ? -ec : ec;
/* Code values are negative, so the senses of these comparisons
are accurate */
if(ec < MP_LAST_CODE || ec > MP_OKAY) {
return mp_err_string[0]; /* unknown error code */
} else {
return mp_err_string[aec + 1];
}
} /* end mp_strerror() */
/* }}} */
/*========================================================================*/
/*------------------------------------------------------------------------*/
/* Static function definitions (internal use only) */
/* {{{ Memory management */
/* {{{ s_mp_grow(mp, min) */
/* Make sure there are at least 'min' digits allocated to mp */
mp_err s_mp_grow(mp_int *mp, mp_size min)
{
if(min > ALLOC(mp)) {
mp_digit *tmp;
/* Set min to next nearest default precision block size */
min = MP_ROUNDUP(min, s_mp_defprec);
if((tmp = s_mp_alloc(min, sizeof(mp_digit), FLAG(mp))) == NULL)
return MP_MEM;
s_mp_copy(DIGITS(mp), tmp, USED(mp));
#if MP_CRYPTO
s_mp_setz(DIGITS(mp), ALLOC(mp));
#endif
s_mp_free(DIGITS(mp), ALLOC(mp));
DIGITS(mp) = tmp;
ALLOC(mp) = min;
}
return MP_OKAY;
} /* end s_mp_grow() */
/* }}} */
/* {{{ s_mp_pad(mp, min) */
/* Make sure the used size of mp is at least 'min', growing if needed */
mp_err s_mp_pad(mp_int *mp, mp_size min)
{
if(min > USED(mp)) {
mp_err res;
/* Make sure there is room to increase precision */
if (min > ALLOC(mp)) {
if ((res = s_mp_grow(mp, min)) != MP_OKAY)
return res;
} else {
s_mp_setz(DIGITS(mp) + USED(mp), min - USED(mp));
}
/* Increase precision; should already be 0-filled */
USED(mp) = min;
}
return MP_OKAY;
} /* end s_mp_pad() */
/* }}} */
/* {{{ s_mp_setz(dp, count) */
#if MP_MACRO == 0
/* Set 'count' digits pointed to by dp to be zeroes */
void s_mp_setz(mp_digit *dp, mp_size count)
{
#if MP_MEMSET == 0
int ix;
for(ix = 0; ix < count; ix++)
dp[ix] = 0;
#else
memset(dp, 0, count * sizeof(mp_digit));
#endif
} /* end s_mp_setz() */
#endif
/* }}} */
/* {{{ s_mp_copy(sp, dp, count) */
#if MP_MACRO == 0
/* Copy 'count' digits from sp to dp */
void s_mp_copy(const mp_digit *sp, mp_digit *dp, mp_size count)
{
#if MP_MEMCPY == 0
int ix;
for(ix = 0; ix < count; ix++)
dp[ix] = sp[ix];
#else
memcpy(dp, sp, count * sizeof(mp_digit));
#endif
} /* end s_mp_copy() */
#endif
/* }}} */
/* {{{ s_mp_alloc(nb, ni, kmflag) */
#if MP_MACRO == 0
/* Allocate ni records of nb bytes each, and return a pointer to that */
void *s_mp_alloc(size_t nb, size_t ni, int kmflag)
{
mp_int *mp;
++mp_allocs;
#ifdef _KERNEL
mp = kmem_zalloc(nb * ni, kmflag);
if (mp != NULL)
FLAG(mp) = kmflag;
return (mp);
#else
return calloc(nb, ni);
#endif
} /* end s_mp_alloc() */
#endif
/* }}} */
/* {{{ s_mp_free(ptr) */
#if MP_MACRO == 0
/* Free the memory pointed to by ptr */
void s_mp_free(void *ptr, mp_size alloc)
{
if(ptr) {
++mp_frees;
#ifdef _KERNEL
kmem_free(ptr, alloc * sizeof (mp_digit));
#else
free(ptr);
#endif
}
} /* end s_mp_free() */
#endif
/* }}} */
/* {{{ s_mp_clamp(mp) */
#if MP_MACRO == 0
/* Remove leading zeroes from the given value */
void s_mp_clamp(mp_int *mp)
{
mp_size used = MP_USED(mp);
while (used > 1 && DIGIT(mp, used - 1) == 0)
--used;
MP_USED(mp) = used;
} /* end s_mp_clamp() */
#endif
/* }}} */
/* {{{ s_mp_exch(a, b) */
/* Exchange the data for a and b; (b, a) = (a, b) */
void s_mp_exch(mp_int *a, mp_int *b)
{
mp_int tmp;
tmp = *a;
*a = *b;
*b = tmp;
} /* end s_mp_exch() */
/* }}} */
/* }}} */
/* {{{ Arithmetic helpers */
/* {{{ s_mp_lshd(mp, p) */
/*
Shift mp leftward by p digits, growing if needed, and zero-filling
the in-shifted digits at the right end. This is a convenient
alternative to multiplication by powers of the radix
The value of USED(mp) must already have been set to the value for
the shifted result.
*/
mp_err s_mp_lshd(mp_int *mp, mp_size p)
{
mp_err res;
mp_size pos;
int ix;
if(p == 0)
return MP_OKAY;
if (MP_USED(mp) == 1 && MP_DIGIT(mp, 0) == 0)
return MP_OKAY;
if((res = s_mp_pad(mp, USED(mp) + p)) != MP_OKAY)
return res;
pos = USED(mp) - 1;
/* Shift all the significant figures over as needed */
for(ix = pos - p; ix >= 0; ix--)
DIGIT(mp, ix + p) = DIGIT(mp, ix);
/* Fill the bottom digits with zeroes */
for(ix = 0; ix < p; ix++)
DIGIT(mp, ix) = 0;
return MP_OKAY;
} /* end s_mp_lshd() */
/* }}} */
/* {{{ s_mp_mul_2d(mp, d) */
/*
Multiply the integer by 2^d, where d is a number of bits. This
amounts to a bitwise shift of the value.
*/
mp_err s_mp_mul_2d(mp_int *mp, mp_digit d)
{
mp_err res;
mp_digit dshift, bshift;
mp_digit mask;
ARGCHK(mp != NULL, MP_BADARG);
dshift = d / MP_DIGIT_BIT;
bshift = d % MP_DIGIT_BIT;
/* bits to be shifted out of the top word */
mask = ((mp_digit)~0 << (MP_DIGIT_BIT - bshift));
mask &= MP_DIGIT(mp, MP_USED(mp) - 1);
if (MP_OKAY != (res = s_mp_pad(mp, MP_USED(mp) + dshift + (mask != 0) )))
return res;
if (dshift && MP_OKAY != (res = s_mp_lshd(mp, dshift)))
return res;
if (bshift) {
mp_digit *pa = MP_DIGITS(mp);
mp_digit *alim = pa + MP_USED(mp);
mp_digit prev = 0;
for (pa += dshift; pa < alim; ) {
mp_digit x = *pa;
*pa++ = (x << bshift) | prev;
prev = x >> (DIGIT_BIT - bshift);
}
}
s_mp_clamp(mp);
return MP_OKAY;
} /* end s_mp_mul_2d() */
/* {{{ s_mp_rshd(mp, p) */
/*
Shift mp rightward by p digits. Maintains the invariant that
digits above the precision are all zero. Digits shifted off the
end are lost. Cannot fail.
*/
void s_mp_rshd(mp_int *mp, mp_size p)
{
mp_size ix;
mp_digit *src, *dst;
if(p == 0)
return;
/* Shortcut when all digits are to be shifted off */
if(p >= USED(mp)) {
s_mp_setz(DIGITS(mp), ALLOC(mp));
USED(mp) = 1;
SIGN(mp) = ZPOS;
return;
}
/* Shift all the significant figures over as needed */
dst = MP_DIGITS(mp);
src = dst + p;
for (ix = USED(mp) - p; ix > 0; ix--)
*dst++ = *src++;
MP_USED(mp) -= p;
/* Fill the top digits with zeroes */
while (p-- > 0)
*dst++ = 0;
#if 0
/* Strip off any leading zeroes */
s_mp_clamp(mp);
#endif
} /* end s_mp_rshd() */
/* }}} */
/* {{{ s_mp_div_2(mp) */
/* Divide by two -- take advantage of radix properties to do it fast */
void s_mp_div_2(mp_int *mp)
{
s_mp_div_2d(mp, 1);
} /* end s_mp_div_2() */
/* }}} */
/* {{{ s_mp_mul_2(mp) */
mp_err s_mp_mul_2(mp_int *mp)
{
mp_digit *pd;
int ix, used;
mp_digit kin = 0;
/* Shift digits leftward by 1 bit */
used = MP_USED(mp);
pd = MP_DIGITS(mp);
for (ix = 0; ix < used; ix++) {
mp_digit d = *pd;
*pd++ = (d << 1) | kin;
kin = (d >> (DIGIT_BIT - 1));
}
/* Deal with rollover from last digit */
if (kin) {
if (ix >= ALLOC(mp)) {
mp_err res;
if((res = s_mp_grow(mp, ALLOC(mp) + 1)) != MP_OKAY)
return res;
}
DIGIT(mp, ix) = kin;
USED(mp) += 1;
}
return MP_OKAY;
} /* end s_mp_mul_2() */
/* }}} */
/* {{{ s_mp_mod_2d(mp, d) */
/*
Remainder the integer by 2^d, where d is a number of bits. This
amounts to a bitwise AND of the value, and does not require the full
division code
*/
void s_mp_mod_2d(mp_int *mp, mp_digit d)
{
mp_size ndig = (d / DIGIT_BIT), nbit = (d % DIGIT_BIT);
mp_size ix;
mp_digit dmask;
if(ndig >= USED(mp))
return;
/* Flush all the bits above 2^d in its digit */
dmask = ((mp_digit)1 << nbit) - 1;
DIGIT(mp, ndig) &= dmask;
/* Flush all digits above the one with 2^d in it */
for(ix = ndig + 1; ix < USED(mp); ix++)
DIGIT(mp, ix) = 0;
s_mp_clamp(mp);
} /* end s_mp_mod_2d() */
/* }}} */
/* {{{ s_mp_div_2d(mp, d) */
/*
Divide the integer by 2^d, where d is a number of bits. This
amounts to a bitwise shift of the value, and does not require the
full division code (used in Barrett reduction, see below)
*/
void s_mp_div_2d(mp_int *mp, mp_digit d)
{
int ix;
mp_digit save, next, mask;
s_mp_rshd(mp, d / DIGIT_BIT);
d %= DIGIT_BIT;
if (d) {
mask = ((mp_digit)1 << d) - 1;
save = 0;
for(ix = USED(mp) - 1; ix >= 0; ix--) {
next = DIGIT(mp, ix) & mask;
DIGIT(mp, ix) = (DIGIT(mp, ix) >> d) | (save << (DIGIT_BIT - d));
save = next;
}
}
s_mp_clamp(mp);
} /* end s_mp_div_2d() */
/* }}} */
/* {{{ s_mp_norm(a, b, *d) */
/*
s_mp_norm(a, b, *d)
Normalize a and b for division, where b is the divisor. In order
that we might make good guesses for quotient digits, we want the
leading digit of b to be at least half the radix, which we
accomplish by multiplying a and b by a power of 2. The exponent
(shift count) is placed in *pd, so that the remainder can be shifted
back at the end of the division process.
*/
mp_err s_mp_norm(mp_int *a, mp_int *b, mp_digit *pd)
{
mp_digit d;
mp_digit mask;
mp_digit b_msd;
mp_err res = MP_OKAY;
d = 0;
mask = DIGIT_MAX & ~(DIGIT_MAX >> 1); /* mask is msb of digit */
b_msd = DIGIT(b, USED(b) - 1);
while (!(b_msd & mask)) {
b_msd <<= 1;
++d;
}
if (d) {
MP_CHECKOK( s_mp_mul_2d(a, d) );
MP_CHECKOK( s_mp_mul_2d(b, d) );
}
*pd = d;
CLEANUP:
return res;
} /* end s_mp_norm() */
/* }}} */
/* }}} */
/* {{{ Primitive digit arithmetic */
/* {{{ s_mp_add_d(mp, d) */
/* Add d to |mp| in place */
mp_err s_mp_add_d(mp_int *mp, mp_digit d) /* unsigned digit addition */
{
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
mp_word w, k = 0;
mp_size ix = 1;
w = (mp_word)DIGIT(mp, 0) + d;
DIGIT(mp, 0) = ACCUM(w);
k = CARRYOUT(w);
while(ix < USED(mp) && k) {
w = (mp_word)DIGIT(mp, ix) + k;
DIGIT(mp, ix) = ACCUM(w);
k = CARRYOUT(w);
++ix;
}
if(k != 0) {
mp_err res;
if((res = s_mp_pad(mp, USED(mp) + 1)) != MP_OKAY)
return res;
DIGIT(mp, ix) = (mp_digit)k;
}
return MP_OKAY;
#else
mp_digit * pmp = MP_DIGITS(mp);
mp_digit sum, mp_i, carry = 0;
mp_err res = MP_OKAY;
int used = (int)MP_USED(mp);
mp_i = *pmp;
*pmp++ = sum = d + mp_i;
carry = (sum < d);
while (carry && --used > 0) {
mp_i = *pmp;
*pmp++ = sum = carry + mp_i;
carry = !sum;
}
if (carry && !used) {
/* mp is growing */
used = MP_USED(mp);
MP_CHECKOK( s_mp_pad(mp, used + 1) );
MP_DIGIT(mp, used) = carry;
}
CLEANUP:
return res;
#endif
} /* end s_mp_add_d() */
/* }}} */
/* {{{ s_mp_sub_d(mp, d) */
/* Subtract d from |mp| in place, assumes |mp| > d */
mp_err s_mp_sub_d(mp_int *mp, mp_digit d) /* unsigned digit subtract */
{
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_SUB_WORD)
mp_word w, b = 0;
mp_size ix = 1;
/* Compute initial subtraction */
w = (RADIX + (mp_word)DIGIT(mp, 0)) - d;
b = CARRYOUT(w) ? 0 : 1;
DIGIT(mp, 0) = ACCUM(w);
/* Propagate borrows leftward */
while(b && ix < USED(mp)) {
w = (RADIX + (mp_word)DIGIT(mp, ix)) - b;
b = CARRYOUT(w) ? 0 : 1;
DIGIT(mp, ix) = ACCUM(w);
++ix;
}
/* Remove leading zeroes */
s_mp_clamp(mp);
/* If we have a borrow out, it's a violation of the input invariant */
if(b)
return MP_RANGE;
else
return MP_OKAY;
#else
mp_digit *pmp = MP_DIGITS(mp);
mp_digit mp_i, diff, borrow;
mp_size used = MP_USED(mp);
mp_i = *pmp;
*pmp++ = diff = mp_i - d;
borrow = (diff > mp_i);
while (borrow && --used) {
mp_i = *pmp;
*pmp++ = diff = mp_i - borrow;
borrow = (diff > mp_i);
}
s_mp_clamp(mp);
return (borrow && !used) ? MP_RANGE : MP_OKAY;
#endif
} /* end s_mp_sub_d() */
/* }}} */
/* {{{ s_mp_mul_d(a, d) */
/* Compute a = a * d, single digit multiplication */
mp_err s_mp_mul_d(mp_int *a, mp_digit d)
{
mp_err res;
mp_size used;
int pow;
if (!d) {
mp_zero(a);
return MP_OKAY;
}
if (d == 1)
return MP_OKAY;
if (0 <= (pow = s_mp_ispow2d(d))) {
return s_mp_mul_2d(a, (mp_digit)pow);
}
used = MP_USED(a);
MP_CHECKOK( s_mp_pad(a, used + 1) );
s_mpv_mul_d(MP_DIGITS(a), used, d, MP_DIGITS(a));
s_mp_clamp(a);
CLEANUP:
return res;
} /* end s_mp_mul_d() */
/* }}} */
/* {{{ s_mp_div_d(mp, d, r) */
/*
s_mp_div_d(mp, d, r)
Compute the quotient mp = mp / d and remainder r = mp mod d, for a
single digit d. If r is null, the remainder will be discarded.
*/
mp_err s_mp_div_d(mp_int *mp, mp_digit d, mp_digit *r)
{
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_DIV_WORD)
mp_word w = 0, q;
#else
mp_digit w, q;
#endif
int ix;
mp_err res;
mp_int quot;
mp_int rem;
if(d == 0)
return MP_RANGE;
if (d == 1) {
if (r)
*r = 0;
return MP_OKAY;
}
/* could check for power of 2 here, but mp_div_d does that. */
if (MP_USED(mp) == 1) {
mp_digit n = MP_DIGIT(mp,0);
mp_digit rem;
q = n / d;
rem = n % d;
MP_DIGIT(mp,0) = q;
if (r)
*r = rem;
return MP_OKAY;
}
MP_DIGITS(&rem) = 0;
MP_DIGITS(") = 0;
/* Make room for the quotient */
MP_CHECKOK( mp_init_size(", USED(mp), FLAG(mp)) );
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_DIV_WORD)
for(ix = USED(mp) - 1; ix >= 0; ix--) {
w = (w << DIGIT_BIT) | DIGIT(mp, ix);
if(w >= d) {
q = w / d;
w = w % d;
} else {
q = 0;
}
s_mp_lshd(", 1);
DIGIT(", 0) = (mp_digit)q;
}
#else
{
mp_digit p;
#if !defined(MP_ASSEMBLY_DIV_2DX1D)
mp_digit norm;
#endif
MP_CHECKOK( mp_init_copy(&rem, mp) );
#if !defined(MP_ASSEMBLY_DIV_2DX1D)
MP_DIGIT(", 0) = d;
MP_CHECKOK( s_mp_norm(&rem, ", &norm) );
if (norm)
d <<= norm;
MP_DIGIT(", 0) = 0;
#endif
p = 0;
for (ix = USED(&rem) - 1; ix >= 0; ix--) {
w = DIGIT(&rem, ix);
if (p) {
MP_CHECKOK( s_mpv_div_2dx1d(p, w, d, &q, &w) );
} else if (w >= d) {
q = w / d;
w = w % d;
} else {
q = 0;
}
MP_CHECKOK( s_mp_lshd(", 1) );
DIGIT(", 0) = q;
p = w;
}
#if !defined(MP_ASSEMBLY_DIV_2DX1D)
if (norm)
w >>= norm;
#endif
}
#endif
/* Deliver the remainder, if desired */
if(r)
*r = (mp_digit)w;
s_mp_clamp(");
mp_exch(", mp);
CLEANUP:
mp_clear(");
mp_clear(&rem);
return res;
} /* end s_mp_div_d() */
/* }}} */
/* }}} */
/* {{{ Primitive full arithmetic */
/* {{{ s_mp_add(a, b) */
/* Compute a = |a| + |b| */
mp_err s_mp_add(mp_int *a, const mp_int *b) /* magnitude addition */
{
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
mp_word w = 0;
#else
mp_digit d, sum, carry = 0;
#endif
mp_digit *pa, *pb;
mp_size ix;
mp_size used;
mp_err res;
/* Make sure a has enough precision for the output value */
if((USED(b) > USED(a)) && (res = s_mp_pad(a, USED(b))) != MP_OKAY)
return res;
/*
Add up all digits up to the precision of b. If b had initially
the same precision as a, or greater, we took care of it by the
padding step above, so there is no problem. If b had initially
less precision, we'll have to make sure the carry out is duly
propagated upward among the higher-order digits of the sum.
*/
pa = MP_DIGITS(a);
pb = MP_DIGITS(b);
used = MP_USED(b);
for(ix = 0; ix < used; ix++) {
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
w = w + *pa + *pb++;
*pa++ = ACCUM(w);
w = CARRYOUT(w);
#else
d = *pa;
sum = d + *pb++;
d = (sum < d); /* detect overflow */
*pa++ = sum += carry;
carry = d + (sum < carry); /* detect overflow */
#endif
}
/* If we run out of 'b' digits before we're actually done, make
sure the carries get propagated upward...
*/
used = MP_USED(a);
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
while (w && ix < used) {
w = w + *pa;
*pa++ = ACCUM(w);
w = CARRYOUT(w);
++ix;
}
#else
while (carry && ix < used) {
sum = carry + *pa;
*pa++ = sum;
carry = !sum;
++ix;
}
#endif
/* If there's an overall carry out, increase precision and include
it. We could have done this initially, but why touch the memory
allocator unless we're sure we have to?
*/
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
if (w) {
if((res = s_mp_pad(a, used + 1)) != MP_OKAY)
return res;
DIGIT(a, ix) = (mp_digit)w;
}
#else
if (carry) {
if((res = s_mp_pad(a, used + 1)) != MP_OKAY)
return res;
DIGIT(a, used) = carry;
}
#endif
return MP_OKAY;
} /* end s_mp_add() */
/* }}} */
/* Compute c = |a| + |b| */ /* magnitude addition */
mp_err s_mp_add_3arg(const mp_int *a, const mp_int *b, mp_int *c)
{
mp_digit *pa, *pb, *pc;
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
mp_word w = 0;
#else
mp_digit sum, carry = 0, d;
#endif
mp_size ix;
mp_size used;
mp_err res;
MP_SIGN(c) = MP_SIGN(a);
if (MP_USED(a) < MP_USED(b)) {
const mp_int *xch = a;
a = b;
b = xch;
}
/* Make sure a has enough precision for the output value */
if (MP_OKAY != (res = s_mp_pad(c, MP_USED(a))))
return res;
/*
Add up all digits up to the precision of b. If b had initially
the same precision as a, or greater, we took care of it by the
exchange step above, so there is no problem. If b had initially
less precision, we'll have to make sure the carry out is duly
propagated upward among the higher-order digits of the sum.
*/
pa = MP_DIGITS(a);
pb = MP_DIGITS(b);
pc = MP_DIGITS(c);
used = MP_USED(b);
for (ix = 0; ix < used; ix++) {
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
w = w + *pa++ + *pb++;
*pc++ = ACCUM(w);
w = CARRYOUT(w);
#else
d = *pa++;
sum = d + *pb++;
d = (sum < d); /* detect overflow */
*pc++ = sum += carry;
carry = d + (sum < carry); /* detect overflow */
#endif
}
/* If we run out of 'b' digits before we're actually done, make
sure the carries get propagated upward...
*/
for (used = MP_USED(a); ix < used; ++ix) {
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
w = w + *pa++;
*pc++ = ACCUM(w);
w = CARRYOUT(w);
#else
*pc++ = sum = carry + *pa++;
carry = (sum < carry);
#endif
}
/* If there's an overall carry out, increase precision and include
it. We could have done this initially, but why touch the memory
allocator unless we're sure we have to?
*/
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
if (w) {
if((res = s_mp_pad(c, used + 1)) != MP_OKAY)
return res;
DIGIT(c, used) = (mp_digit)w;
++used;
}
#else
if (carry) {
if((res = s_mp_pad(c, used + 1)) != MP_OKAY)
return res;
DIGIT(c, used) = carry;
++used;
}
#endif
MP_USED(c) = used;
return MP_OKAY;
}
/* {{{ s_mp_add_offset(a, b, offset) */
/* Compute a = |a| + ( |b| * (RADIX ** offset) ) */
mp_err s_mp_add_offset(mp_int *a, mp_int *b, mp_size offset)
{
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
mp_word w, k = 0;
#else
mp_digit d, sum, carry = 0;
#endif
mp_size ib;
mp_size ia;
mp_size lim;
mp_err res;
/* Make sure a has enough precision for the output value */
lim = MP_USED(b) + offset;
if((lim > USED(a)) && (res = s_mp_pad(a, lim)) != MP_OKAY)
return res;
/*
Add up all digits up to the precision of b. If b had initially
the same precision as a, or greater, we took care of it by the
padding step above, so there is no problem. If b had initially
less precision, we'll have to make sure the carry out is duly
propagated upward among the higher-order digits of the sum.
*/
lim = USED(b);
for(ib = 0, ia = offset; ib < lim; ib++, ia++) {
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
w = (mp_word)DIGIT(a, ia) + DIGIT(b, ib) + k;
DIGIT(a, ia) = ACCUM(w);
k = CARRYOUT(w);
#else
d = MP_DIGIT(a, ia);
sum = d + MP_DIGIT(b, ib);
d = (sum < d);
MP_DIGIT(a,ia) = sum += carry;
carry = d + (sum < carry);
#endif
}
/* If we run out of 'b' digits before we're actually done, make
sure the carries get propagated upward...
*/
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
for (lim = MP_USED(a); k && (ia < lim); ++ia) {
w = (mp_word)DIGIT(a, ia) + k;
DIGIT(a, ia) = ACCUM(w);
k = CARRYOUT(w);
}
#else
for (lim = MP_USED(a); carry && (ia < lim); ++ia) {
d = MP_DIGIT(a, ia);
MP_DIGIT(a,ia) = sum = d + carry;
carry = (sum < d);
}
#endif
/* If there's an overall carry out, increase precision and include
it. We could have done this initially, but why touch the memory
allocator unless we're sure we have to?
*/
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
if(k) {
if((res = s_mp_pad(a, USED(a) + 1)) != MP_OKAY)
return res;
DIGIT(a, ia) = (mp_digit)k;
}
#else
if (carry) {
if((res = s_mp_pad(a, lim + 1)) != MP_OKAY)
return res;
DIGIT(a, lim) = carry;
}
#endif
s_mp_clamp(a);
return MP_OKAY;
} /* end s_mp_add_offset() */
/* }}} */
/* {{{ s_mp_sub(a, b) */
/* Compute a = |a| - |b|, assumes |a| >= |b| */
mp_err s_mp_sub(mp_int *a, const mp_int *b) /* magnitude subtract */
{
mp_digit *pa, *pb, *limit;
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_SUB_WORD)
mp_sword w = 0;
#else
mp_digit d, diff, borrow = 0;
#endif
/*
Subtract and propagate borrow. Up to the precision of b, this
accounts for the digits of b; after that, we just make sure the
carries get to the right place. This saves having to pad b out to
the precision of a just to make the loops work right...
*/
pa = MP_DIGITS(a);
pb = MP_DIGITS(b);
limit = pb + MP_USED(b);
while (pb < limit) {
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_SUB_WORD)
w = w + *pa - *pb++;
*pa++ = ACCUM(w);
w >>= MP_DIGIT_BIT;
#else
d = *pa;
diff = d - *pb++;
d = (diff > d); /* detect borrow */
if (borrow && --diff == MP_DIGIT_MAX)
++d;
*pa++ = diff;
borrow = d;
#endif
}
limit = MP_DIGITS(a) + MP_USED(a);
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_SUB_WORD)
while (w && pa < limit) {
w = w + *pa;
*pa++ = ACCUM(w);
w >>= MP_DIGIT_BIT;
}
#else
while (borrow && pa < limit) {
d = *pa;
*pa++ = diff = d - borrow;
borrow = (diff > d);
}
#endif
/* Clobber any leading zeroes we created */
s_mp_clamp(a);
/*
If there was a borrow out, then |b| > |a| in violation
of our input invariant. We've already done the work,
but we'll at least complain about it...
*/
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_SUB_WORD)
return w ? MP_RANGE : MP_OKAY;
#else
return borrow ? MP_RANGE : MP_OKAY;
#endif
} /* end s_mp_sub() */
/* }}} */
/* Compute c = |a| - |b|, assumes |a| >= |b| */ /* magnitude subtract */
mp_err s_mp_sub_3arg(const mp_int *a, const mp_int *b, mp_int *c)
{
mp_digit *pa, *pb, *pc;
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_SUB_WORD)
mp_sword w = 0;
#else
mp_digit d, diff, borrow = 0;
#endif
int ix, limit;
mp_err res;
MP_SIGN(c) = MP_SIGN(a);
/* Make sure a has enough precision for the output value */
if (MP_OKAY != (res = s_mp_pad(c, MP_USED(a))))
return res;
/*
Subtract and propagate borrow. Up to the precision of b, this
accounts for the digits of b; after that, we just make sure the
carries get to the right place. This saves having to pad b out to
the precision of a just to make the loops work right...
*/
pa = MP_DIGITS(a);
pb = MP_DIGITS(b);
pc = MP_DIGITS(c);
limit = MP_USED(b);
for (ix = 0; ix < limit; ++ix) {
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_SUB_WORD)
w = w + *pa++ - *pb++;
*pc++ = ACCUM(w);
w >>= MP_DIGIT_BIT;
#else
d = *pa++;
diff = d - *pb++;
d = (diff > d);
if (borrow && --diff == MP_DIGIT_MAX)
++d;
*pc++ = diff;
borrow = d;
#endif
}
for (limit = MP_USED(a); ix < limit; ++ix) {
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_SUB_WORD)
w = w + *pa++;
*pc++ = ACCUM(w);
w >>= MP_DIGIT_BIT;
#else
d = *pa++;
*pc++ = diff = d - borrow;
borrow = (diff > d);
#endif
}
/* Clobber any leading zeroes we created */
MP_USED(c) = ix;
s_mp_clamp(c);
/*
If there was a borrow out, then |b| > |a| in violation
of our input invariant. We've already done the work,
but we'll at least complain about it...
*/
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_SUB_WORD)
return w ? MP_RANGE : MP_OKAY;
#else
return borrow ? MP_RANGE : MP_OKAY;
#endif
}
/* {{{ s_mp_mul(a, b) */
/* Compute a = |a| * |b| */
mp_err s_mp_mul(mp_int *a, const mp_int *b)
{
return mp_mul(a, b, a);
} /* end s_mp_mul() */
/* }}} */
#if defined(MP_USE_UINT_DIGIT) && defined(MP_USE_LONG_LONG_MULTIPLY)
/* This trick works on Sparc V8 CPUs with the Workshop compilers. */
#define MP_MUL_DxD(a, b, Phi, Plo) \
{ unsigned long long product = (unsigned long long)a * b; \
Plo = (mp_digit)product; \
Phi = (mp_digit)(product >> MP_DIGIT_BIT); }
#elif defined(OSF1)
#define MP_MUL_DxD(a, b, Phi, Plo) \
{ Plo = asm ("mulq %a0, %a1, %v0", a, b);\
Phi = asm ("umulh %a0, %a1, %v0", a, b); }
#else
#define MP_MUL_DxD(a, b, Phi, Plo) \
{ mp_digit a0b1, a1b0; \
Plo = (a & MP_HALF_DIGIT_MAX) * (b & MP_HALF_DIGIT_MAX); \
Phi = (a >> MP_HALF_DIGIT_BIT) * (b >> MP_HALF_DIGIT_BIT); \
a0b1 = (a & MP_HALF_DIGIT_MAX) * (b >> MP_HALF_DIGIT_BIT); \
a1b0 = (a >> MP_HALF_DIGIT_BIT) * (b & MP_HALF_DIGIT_MAX); \
a1b0 += a0b1; \
Phi += a1b0 >> MP_HALF_DIGIT_BIT; \
if (a1b0 < a0b1) \
Phi += MP_HALF_RADIX; \
a1b0 <<= MP_HALF_DIGIT_BIT; \
Plo += a1b0; \
if (Plo < a1b0) \
++Phi; \
}
#endif
#if !defined(MP_ASSEMBLY_MULTIPLY)
/* c = a * b */
void s_mpv_mul_d(const mp_digit *a, mp_size a_len, mp_digit b, mp_digit *c)
{
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_MUL_WORD)
mp_digit d = 0;
/* Inner product: Digits of a */
while (a_len--) {
mp_word w = ((mp_word)b * *a++) + d;
*c++ = ACCUM(w);
d = CARRYOUT(w);
}
*c = d;
#else
mp_digit carry = 0;
while (a_len--) {
mp_digit a_i = *a++;
mp_digit a0b0, a1b1;
MP_MUL_DxD(a_i, b, a1b1, a0b0);
a0b0 += carry;
if (a0b0 < carry)
++a1b1;
*c++ = a0b0;
carry = a1b1;
}
*c = carry;
#endif
}
/* c += a * b */
void s_mpv_mul_d_add(const mp_digit *a, mp_size a_len, mp_digit b,
mp_digit *c)
{
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_MUL_WORD)
mp_digit d = 0;
/* Inner product: Digits of a */
while (a_len--) {
mp_word w = ((mp_word)b * *a++) + *c + d;
*c++ = ACCUM(w);
d = CARRYOUT(w);
}
*c = d;
#else
mp_digit carry = 0;
while (a_len--) {
mp_digit a_i = *a++;
mp_digit a0b0, a1b1;
MP_MUL_DxD(a_i, b, a1b1, a0b0);
a0b0 += carry;
if (a0b0 < carry)
++a1b1;
a0b0 += a_i = *c;
if (a0b0 < a_i)
++a1b1;
*c++ = a0b0;
carry = a1b1;
}
*c = carry;
#endif
}
/* Presently, this is only used by the Montgomery arithmetic code. */
/* c += a * b */
void s_mpv_mul_d_add_prop(const mp_digit *a, mp_size a_len, mp_digit b, mp_digit *c)
{
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_MUL_WORD)
mp_digit d = 0;
/* Inner product: Digits of a */
while (a_len--) {
mp_word w = ((mp_word)b * *a++) + *c + d;
*c++ = ACCUM(w);
d = CARRYOUT(w);
}
while (d) {
mp_word w = (mp_word)*c + d;
*c++ = ACCUM(w);
d = CARRYOUT(w);
}
#else
mp_digit carry = 0;
while (a_len--) {
mp_digit a_i = *a++;
mp_digit a0b0, a1b1;
MP_MUL_DxD(a_i, b, a1b1, a0b0);
a0b0 += carry;
if (a0b0 < carry)
++a1b1;
a0b0 += a_i = *c;
if (a0b0 < a_i)
++a1b1;
*c++ = a0b0;
carry = a1b1;
}
while (carry) {
mp_digit c_i = *c;
carry += c_i;
*c++ = carry;
carry = carry < c_i;
}
#endif
}
#endif
#if defined(MP_USE_UINT_DIGIT) && defined(MP_USE_LONG_LONG_MULTIPLY)
/* This trick works on Sparc V8 CPUs with the Workshop compilers. */
#define MP_SQR_D(a, Phi, Plo) \
{ unsigned long long square = (unsigned long long)a * a; \
Plo = (mp_digit)square; \
Phi = (mp_digit)(square >> MP_DIGIT_BIT); }
#elif defined(OSF1)
#define MP_SQR_D(a, Phi, Plo) \
{ Plo = asm ("mulq %a0, %a0, %v0", a);\
Phi = asm ("umulh %a0, %a0, %v0", a); }
#else
#define MP_SQR_D(a, Phi, Plo) \
{ mp_digit Pmid; \
Plo = (a & MP_HALF_DIGIT_MAX) * (a & MP_HALF_DIGIT_MAX); \
Phi = (a >> MP_HALF_DIGIT_BIT) * (a >> MP_HALF_DIGIT_BIT); \
Pmid = (a & MP_HALF_DIGIT_MAX) * (a >> MP_HALF_DIGIT_BIT); \
Phi += Pmid >> (MP_HALF_DIGIT_BIT - 1); \
Pmid <<= (MP_HALF_DIGIT_BIT + 1); \
Plo += Pmid; \
if (Plo < Pmid) \
++Phi; \
}
#endif
#if !defined(MP_ASSEMBLY_SQUARE)
/* Add the squares of the digits of a to the digits of b. */
void s_mpv_sqr_add_prop(const mp_digit *pa, mp_size a_len, mp_digit *ps)
{
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_MUL_WORD)
mp_word w;
mp_digit d;
mp_size ix;
w = 0;
#define ADD_SQUARE(n) \
d = pa[n]; \
w += (d * (mp_word)d) + ps[2*n]; \
ps[2*n] = ACCUM(w); \
w = (w >> DIGIT_BIT) + ps[2*n+1]; \
ps[2*n+1] = ACCUM(w); \
w = (w >> DIGIT_BIT)
for (ix = a_len; ix >= 4; ix -= 4) {
ADD_SQUARE(0);
ADD_SQUARE(1);
ADD_SQUARE(2);
ADD_SQUARE(3);
pa += 4;
ps += 8;
}
if (ix) {
ps += 2*ix;
pa += ix;
switch (ix) {
case 3: ADD_SQUARE(-3); /* FALLTHRU */
case 2: ADD_SQUARE(-2); /* FALLTHRU */
case 1: ADD_SQUARE(-1); /* FALLTHRU */
case 0: break;
}
}
while (w) {
w += *ps;
*ps++ = ACCUM(w);
w = (w >> DIGIT_BIT);
}
#else
mp_digit carry = 0;
while (a_len--) {
mp_digit a_i = *pa++;
mp_digit a0a0, a1a1;
MP_SQR_D(a_i, a1a1, a0a0);
/* here a1a1 and a0a0 constitute a_i ** 2 */
a0a0 += carry;
if (a0a0 < carry)
++a1a1;
/* now add to ps */
a0a0 += a_i = *ps;
if (a0a0 < a_i)
++a1a1;
*ps++ = a0a0;
a1a1 += a_i = *ps;
carry = (a1a1 < a_i);
*ps++ = a1a1;
}
while (carry) {
mp_digit s_i = *ps;
carry += s_i;
*ps++ = carry;
carry = carry < s_i;
}
#endif
}
#endif
#if (defined(MP_NO_MP_WORD) || defined(MP_NO_DIV_WORD)) \
&& !defined(MP_ASSEMBLY_DIV_2DX1D)
/*
** Divide 64-bit (Nhi,Nlo) by 32-bit divisor, which must be normalized
** so its high bit is 1. This code is from NSPR.
*/
mp_err s_mpv_div_2dx1d(mp_digit Nhi, mp_digit Nlo, mp_digit divisor,
mp_digit *qp, mp_digit *rp)
{
mp_digit d1, d0, q1, q0;
mp_digit r1, r0, m;
d1 = divisor >> MP_HALF_DIGIT_BIT;
d0 = divisor & MP_HALF_DIGIT_MAX;
r1 = Nhi % d1;
q1 = Nhi / d1;
m = q1 * d0;
r1 = (r1 << MP_HALF_DIGIT_BIT) | (Nlo >> MP_HALF_DIGIT_BIT);
if (r1 < m) {
q1--, r1 += divisor;
if (r1 >= divisor && r1 < m) {
q1--, r1 += divisor;
}
}
r1 -= m;
r0 = r1 % d1;
q0 = r1 / d1;
m = q0 * d0;
r0 = (r0 << MP_HALF_DIGIT_BIT) | (Nlo & MP_HALF_DIGIT_MAX);
if (r0 < m) {
q0--, r0 += divisor;
if (r0 >= divisor && r0 < m) {
q0--, r0 += divisor;
}
}
if (qp)
*qp = (q1 << MP_HALF_DIGIT_BIT) | q0;
if (rp)
*rp = r0 - m;
return MP_OKAY;
}
#endif
#if MP_SQUARE
/* {{{ s_mp_sqr(a) */
mp_err s_mp_sqr(mp_int *a)
{
mp_err res;
mp_int tmp;
if((res = mp_init_size(&tmp, 2 * USED(a), FLAG(a))) != MP_OKAY)
return res;
res = mp_sqr(a, &tmp);
if (res == MP_OKAY) {
s_mp_exch(&tmp, a);
}
mp_clear(&tmp);
return res;
}
/* }}} */
#endif
/* {{{ s_mp_div(a, b) */
/*
s_mp_div(a, b)
Compute a = a / b and b = a mod b. Assumes b > a.
*/
mp_err s_mp_div(mp_int *rem, /* i: dividend, o: remainder */
mp_int *div, /* i: divisor */
mp_int *quot) /* i: 0; o: quotient */
{
mp_int part, t;
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_DIV_WORD)
mp_word q_msd;
#else
mp_digit q_msd;
#endif
mp_err res;
mp_digit d;
mp_digit div_msd;
int ix;
if(mp_cmp_z(div) == 0)
return MP_RANGE;
/* Shortcut if divisor is power of two */
if((ix = s_mp_ispow2(div)) >= 0) {
MP_CHECKOK( mp_copy(rem, quot) );
s_mp_div_2d(quot, (mp_digit)ix);
s_mp_mod_2d(rem, (mp_digit)ix);
return MP_OKAY;
}
DIGITS(&t) = 0;
MP_SIGN(rem) = ZPOS;
MP_SIGN(div) = ZPOS;
/* A working temporary for division */
MP_CHECKOK( mp_init_size(&t, MP_ALLOC(rem), FLAG(rem)));
/* Normalize to optimize guessing */
MP_CHECKOK( s_mp_norm(rem, div, &d) );
part = *rem;
/* Perform the division itself...woo! */
MP_USED(quot) = MP_ALLOC(quot);
/* Find a partial substring of rem which is at least div */
/* If we didn't find one, we're finished dividing */
while (MP_USED(rem) > MP_USED(div) || s_mp_cmp(rem, div) >= 0) {
int i;
int unusedRem;
unusedRem = MP_USED(rem) - MP_USED(div);
MP_DIGITS(&part) = MP_DIGITS(rem) + unusedRem;
MP_ALLOC(&part) = MP_ALLOC(rem) - unusedRem;
MP_USED(&part) = MP_USED(div);
if (s_mp_cmp(&part, div) < 0) {
-- unusedRem;
#if MP_ARGCHK == 2
assert(unusedRem >= 0);
#endif
-- MP_DIGITS(&part);
++ MP_USED(&part);
++ MP_ALLOC(&part);
}
/* Compute a guess for the next quotient digit */
q_msd = MP_DIGIT(&part, MP_USED(&part) - 1);
div_msd = MP_DIGIT(div, MP_USED(div) - 1);
if (q_msd >= div_msd) {
q_msd = 1;
} else if (MP_USED(&part) > 1) {
#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_DIV_WORD)
q_msd = (q_msd << MP_DIGIT_BIT) | MP_DIGIT(&part, MP_USED(&part) - 2);
q_msd /= div_msd;
if (q_msd == RADIX)
--q_msd;
#else
mp_digit r;
MP_CHECKOK( s_mpv_div_2dx1d(q_msd, MP_DIGIT(&part, MP_USED(&part) - 2),
div_msd, &q_msd, &r) );
#endif
} else {
q_msd = 0;
}
#if MP_ARGCHK == 2
assert(q_msd > 0); /* This case should never occur any more. */
#endif
if (q_msd <= 0)
break;
/* See what that multiplies out to */
mp_copy(div, &t);
MP_CHECKOK( s_mp_mul_d(&t, (mp_digit)q_msd) );
/*
If it's too big, back it off. We should not have to do this
more than once, or, in rare cases, twice. Knuth describes a
method by which this could be reduced to a maximum of once, but
I didn't implement that here.
* When using s_mpv_div_2dx1d, we may have to do this 3 times.
*/
for (i = 4; s_mp_cmp(&t, &part) > 0 && i > 0; --i) {
--q_msd;
s_mp_sub(&t, div); /* t -= div */
}
if (i < 0) {
res = MP_RANGE;
goto CLEANUP;
}
/* At this point, q_msd should be the right next digit */
MP_CHECKOK( s_mp_sub(&part, &t) ); /* part -= t */
s_mp_clamp(rem);
/*
Include the digit in the quotient. We allocated enough memory
for any quotient we could ever possibly get, so we should not
have to check for failures here
*/
MP_DIGIT(quot, unusedRem) = (mp_digit)q_msd;
}
/* Denormalize remainder */
if (d) {
s_mp_div_2d(rem, d);
}
s_mp_clamp(quot);
CLEANUP:
mp_clear(&t);
return res;
} /* end s_mp_div() */
/* }}} */
/* {{{ s_mp_2expt(a, k) */
mp_err s_mp_2expt(mp_int *a, mp_digit k)
{
mp_err res;
mp_size dig, bit;
dig = k / DIGIT_BIT;
bit = k % DIGIT_BIT;
mp_zero(a);
if((res = s_mp_pad(a, dig + 1)) != MP_OKAY)
return res;
DIGIT(a, dig) |= ((mp_digit)1 << bit);
return MP_OKAY;
} /* end s_mp_2expt() */
/* }}} */
/* {{{ s_mp_reduce(x, m, mu) */
/*
Compute Barrett reduction, x (mod m), given a precomputed value for
mu = b^2k / m, where b = RADIX and k = #digits(m). This should be
faster than straight division, when many reductions by the same
value of m are required (such as in modular exponentiation). This
can nearly halve the time required to do modular exponentiation,
as compared to using the full integer divide to reduce.
This algorithm was derived from the _Handbook of Applied
Cryptography_ by Menezes, Oorschot and VanStone, Ch. 14,
pp. 603-604.
*/
mp_err s_mp_reduce(mp_int *x, const mp_int *m, const mp_int *mu)
{
mp_int q;
mp_err res;
if((res = mp_init_copy(&q, x)) != MP_OKAY)
return res;
s_mp_rshd(&q, USED(m) - 1); /* q1 = x / b^(k-1) */
s_mp_mul(&q, mu); /* q2 = q1 * mu */
s_mp_rshd(&q, USED(m) + 1); /* q3 = q2 / b^(k+1) */
/* x = x mod b^(k+1), quick (no division) */
s_mp_mod_2d(x, DIGIT_BIT * (USED(m) + 1));
/* q = q * m mod b^(k+1), quick (no division) */
s_mp_mul(&q, m);
s_mp_mod_2d(&q, DIGIT_BIT * (USED(m) + 1));
/* x = x - q */
if((res = mp_sub(x, &q, x)) != MP_OKAY)
goto CLEANUP;
/* If x < 0, add b^(k+1) to it */
if(mp_cmp_z(x) < 0) {
mp_set(&q, 1);
if((res = s_mp_lshd(&q, USED(m) + 1)) != MP_OKAY)
goto CLEANUP;
if((res = mp_add(x, &q, x)) != MP_OKAY)
goto CLEANUP;
}
/* Back off if it's too big */
while(mp_cmp(x, m) >= 0) {
if((res = s_mp_sub(x, m)) != MP_OKAY)
break;
}
CLEANUP:
mp_clear(&q);
return res;
} /* end s_mp_reduce() */
/* }}} */
/* }}} */
/* {{{ Primitive comparisons */
/* {{{ s_mp_cmp(a, b) */
/* Compare |a| <=> |b|, return 0 if equal, <0 if a<b, >0 if a>b */
int s_mp_cmp(const mp_int *a, const mp_int *b)
{
mp_size used_a = MP_USED(a);
{
mp_size used_b = MP_USED(b);
if (used_a > used_b)
goto IS_GT;
if (used_a < used_b)
goto IS_LT;
}
{
mp_digit *pa, *pb;
mp_digit da = 0, db = 0;
#define CMP_AB(n) if ((da = pa[n]) != (db = pb[n])) goto done
pa = MP_DIGITS(a) + used_a;
pb = MP_DIGITS(b) + used_a;
while (used_a >= 4) {
pa -= 4;
pb -= 4;
used_a -= 4;
CMP_AB(3);
CMP_AB(2);
CMP_AB(1);
CMP_AB(0);
}
while (used_a-- > 0 && ((da = *--pa) == (db = *--pb)))
/* do nothing */;
done:
if (da > db)
goto IS_GT;
if (da < db)
goto IS_LT;
}
return MP_EQ;
IS_LT:
return MP_LT;
IS_GT:
return MP_GT;
} /* end s_mp_cmp() */
/* }}} */
/* {{{ s_mp_cmp_d(a, d) */
/* Compare |a| <=> d, return 0 if equal, <0 if a<d, >0 if a>d */
int s_mp_cmp_d(const mp_int *a, mp_digit d)
{
if(USED(a) > 1)
return MP_GT;
if(DIGIT(a, 0) < d)
return MP_LT;
else if(DIGIT(a, 0) > d)
return MP_GT;
else
return MP_EQ;
} /* end s_mp_cmp_d() */
/* }}} */
/* {{{ s_mp_ispow2(v) */
/*
Returns -1 if the value is not a power of two; otherwise, it returns
k such that v = 2^k, i.e. lg(v).
*/
int s_mp_ispow2(const mp_int *v)
{
mp_digit d;
int extra = 0, ix;
ix = MP_USED(v) - 1;
d = MP_DIGIT(v, ix); /* most significant digit of v */
extra = s_mp_ispow2d(d);
if (extra < 0 || ix == 0)
return extra;
while (--ix >= 0) {
if (DIGIT(v, ix) != 0)
return -1; /* not a power of two */
extra += MP_DIGIT_BIT;
}
return extra;
} /* end s_mp_ispow2() */
/* }}} */
/* {{{ s_mp_ispow2d(d) */
int s_mp_ispow2d(mp_digit d)
{
if ((d != 0) && ((d & (d-1)) == 0)) { /* d is a power of 2 */
int pow = 0;
#if defined (MP_USE_UINT_DIGIT)
if (d & 0xffff0000U)
pow += 16;
if (d & 0xff00ff00U)
pow += 8;
if (d & 0xf0f0f0f0U)
pow += 4;
if (d & 0xccccccccU)
pow += 2;
if (d & 0xaaaaaaaaU)
pow += 1;
#elif defined(MP_USE_LONG_LONG_DIGIT)
if (d & 0xffffffff00000000ULL)
pow += 32;
if (d & 0xffff0000ffff0000ULL)
pow += 16;
if (d & 0xff00ff00ff00ff00ULL)
pow += 8;
if (d & 0xf0f0f0f0f0f0f0f0ULL)
pow += 4;
if (d & 0xccccccccccccccccULL)
pow += 2;
if (d & 0xaaaaaaaaaaaaaaaaULL)
pow += 1;
#elif defined(MP_USE_LONG_DIGIT)
if (d & 0xffffffff00000000UL)
pow += 32;
if (d & 0xffff0000ffff0000UL)
pow += 16;
if (d & 0xff00ff00ff00ff00UL)
pow += 8;
if (d & 0xf0f0f0f0f0f0f0f0UL)
pow += 4;
if (d & 0xccccccccccccccccUL)
pow += 2;
if (d & 0xaaaaaaaaaaaaaaaaUL)
pow += 1;
#else
#error "unknown type for mp_digit"
#endif
return pow;
}
return -1;
} /* end s_mp_ispow2d() */
/* }}} */
/* }}} */
/* {{{ Primitive I/O helpers */
/* {{{ s_mp_tovalue(ch, r) */
/*
Convert the given character to its digit value, in the given radix.
If the given character is not understood in the given radix, -1 is
returned. Otherwise the digit's numeric value is returned.
The results will be odd if you use a radix < 2 or > 62, you are
expected to know what you're up to.
*/
int s_mp_tovalue(char ch, int r)
{
int val, xch;
if(r > 36)
xch = ch;
else
xch = toupper(ch);
if(isdigit(xch))
val = xch - '0';
else if(isupper(xch))
val = xch - 'A' + 10;
else if(islower(xch))
val = xch - 'a' + 36;
else if(xch == '+')
val = 62;
else if(xch == '/')
val = 63;
else
return -1;
if(val < 0 || val >= r)
return -1;
return val;
} /* end s_mp_tovalue() */
/* }}} */
/* {{{ s_mp_todigit(val, r, low) */
/*
Convert val to a radix-r digit, if possible. If val is out of range
for r, returns zero. Otherwise, returns an ASCII character denoting
the value in the given radix.
The results may be odd if you use a radix < 2 or > 64, you are
expected to know what you're doing.
*/
char s_mp_todigit(mp_digit val, int r, int low)
{
char ch;
if(val >= r)
return 0;
ch = s_dmap_1[val];
if(r <= 36 && low)
ch = tolower(ch);
return ch;
} /* end s_mp_todigit() */
/* }}} */
/* {{{ s_mp_outlen(bits, radix) */
/*
Return an estimate for how long a string is needed to hold a radix
r representation of a number with 'bits' significant bits, plus an
extra for a zero terminator (assuming C style strings here)
*/
int s_mp_outlen(int bits, int r)
{
return (int)((double)bits * LOG_V_2(r) + 1.5) + 1;
} /* end s_mp_outlen() */
/* }}} */
/* }}} */
/* {{{ mp_read_unsigned_octets(mp, str, len) */
/* mp_read_unsigned_octets(mp, str, len)
Read in a raw value (base 256) into the given mp_int
No sign bit, number is positive. Leading zeros ignored.
*/
mp_err
mp_read_unsigned_octets(mp_int *mp, const unsigned char *str, mp_size len)
{
int count;
mp_err res;
mp_digit d;
ARGCHK(mp != NULL && str != NULL && len > 0, MP_BADARG);
mp_zero(mp);
count = len % sizeof(mp_digit);
if (count) {
for (d = 0; count-- > 0; --len) {
d = (d << 8) | *str++;
}
MP_DIGIT(mp, 0) = d;
}
/* Read the rest of the digits */
for(; len > 0; len -= sizeof(mp_digit)) {
for (d = 0, count = sizeof(mp_digit); count > 0; --count) {
d = (d << 8) | *str++;
}
if (MP_EQ == mp_cmp_z(mp)) {
if (!d)
continue;
} else {
if((res = s_mp_lshd(mp, 1)) != MP_OKAY)
return res;
}
MP_DIGIT(mp, 0) = d;
}
return MP_OKAY;
} /* end mp_read_unsigned_octets() */
/* }}} */
/* {{{ mp_unsigned_octet_size(mp) */
int
mp_unsigned_octet_size(const mp_int *mp)
{
int bytes;
int ix;
mp_digit d = 0;
ARGCHK(mp != NULL, MP_BADARG);
ARGCHK(MP_ZPOS == SIGN(mp), MP_BADARG);
bytes = (USED(mp) * sizeof(mp_digit));
/* subtract leading zeros. */
/* Iterate over each digit... */
for(ix = USED(mp) - 1; ix >= 0; ix--) {
d = DIGIT(mp, ix);
if (d)
break;
bytes -= sizeof(d);
}
if (!bytes)
return 1;
/* Have MSD, check digit bytes, high order first */
for(ix = sizeof(mp_digit) - 1; ix >= 0; ix--) {
unsigned char x = (unsigned char)(d >> (ix * CHAR_BIT));
if (x)
break;
--bytes;
}
return bytes;
} /* end mp_unsigned_octet_size() */
/* }}} */
/* {{{ mp_to_unsigned_octets(mp, str) */
/* output a buffer of big endian octets no longer than specified. */
mp_err
mp_to_unsigned_octets(const mp_int *mp, unsigned char *str, mp_size maxlen)
{
int ix, pos = 0;
int bytes;
ARGCHK(mp != NULL && str != NULL && !SIGN(mp), MP_BADARG);
bytes = mp_unsigned_octet_size(mp);
ARGCHK(bytes <= maxlen, MP_BADARG);
/* Iterate over each digit... */
for(ix = USED(mp) - 1; ix >= 0; ix--) {
mp_digit d = DIGIT(mp, ix);
int jx;
/* Unpack digit bytes, high order first */
for(jx = sizeof(mp_digit) - 1; jx >= 0; jx--) {
unsigned char x = (unsigned char)(d >> (jx * CHAR_BIT));
if (!pos && !x) /* suppress leading zeros */
continue;
str[pos++] = x;
}
}
if (!pos)
str[pos++] = 0;
return pos;
} /* end mp_to_unsigned_octets() */
/* }}} */
/* {{{ mp_to_signed_octets(mp, str) */
/* output a buffer of big endian octets no longer than specified. */
mp_err
mp_to_signed_octets(const mp_int *mp, unsigned char *str, mp_size maxlen)
{
int ix, pos = 0;
int bytes;
ARGCHK(mp != NULL && str != NULL && !SIGN(mp), MP_BADARG);
bytes = mp_unsigned_octet_size(mp);
ARGCHK(bytes <= maxlen, MP_BADARG);
/* Iterate over each digit... */
for(ix = USED(mp) - 1; ix >= 0; ix--) {
mp_digit d = DIGIT(mp, ix);
int jx;
/* Unpack digit bytes, high order first */
for(jx = sizeof(mp_digit) - 1; jx >= 0; jx--) {
unsigned char x = (unsigned char)(d >> (jx * CHAR_BIT));
if (!pos) {
if (!x) /* suppress leading zeros */
continue;
if (x & 0x80) { /* add one leading zero to make output positive. */
ARGCHK(bytes + 1 <= maxlen, MP_BADARG);
if (bytes + 1 > maxlen)
return MP_BADARG;
str[pos++] = 0;
}
}
str[pos++] = x;
}
}
if (!pos)
str[pos++] = 0;
return pos;
} /* end mp_to_signed_octets() */
/* }}} */
/* {{{ mp_to_fixlen_octets(mp, str) */
/* output a buffer of big endian octets exactly as long as requested. */
mp_err
mp_to_fixlen_octets(const mp_int *mp, unsigned char *str, mp_size length)
{
int ix, pos = 0;
int bytes;
ARGCHK(mp != NULL && str != NULL && !SIGN(mp), MP_BADARG);
bytes = mp_unsigned_octet_size(mp);
ARGCHK(bytes <= length, MP_BADARG);
/* place any needed leading zeros */
for (;length > bytes; --length) {
*str++ = 0;
}
/* Iterate over each digit... */
for(ix = USED(mp) - 1; ix >= 0; ix--) {
mp_digit d = DIGIT(mp, ix);
int jx;
/* Unpack digit bytes, high order first */
for(jx = sizeof(mp_digit) - 1; jx >= 0; jx--) {
unsigned char x = (unsigned char)(d >> (jx * CHAR_BIT));
if (!pos && !x) /* suppress leading zeros */
continue;
str[pos++] = x;
}
}
if (!pos)
str[pos++] = 0;
return MP_OKAY;
} /* end mp_to_fixlen_octets() */
/* }}} */
/*------------------------------------------------------------------------*/
/* HERE THERE BE DRAGONS */