--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/security/spec/ECFieldF2m.java Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,241 @@
+/*
+ * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package java.security.spec;
+
+import java.math.BigInteger;
+import java.util.Arrays;
+
+/**
+ * This immutable class defines an elliptic curve (EC)
+ * characteristic 2 finite field.
+ *
+ * @see ECField
+ *
+ * @author Valerie Peng
+ *
+ * @since 1.5
+ */
+public class ECFieldF2m implements ECField {
+
+ private int m;
+ private int[] ks;
+ private BigInteger rp;
+
+ /**
+ * Creates an elliptic curve characteristic 2 finite
+ * field which has 2^{@code m} elements with normal basis.
+ * @param m with 2^{@code m} being the number of elements.
+ * @exception IllegalArgumentException if {@code m}
+ * is not positive.
+ */
+ public ECFieldF2m(int m) {
+ if (m <= 0) {
+ throw new IllegalArgumentException("m is not positive");
+ }
+ this.m = m;
+ this.ks = null;
+ this.rp = null;
+ }
+
+ /**
+ * Creates an elliptic curve characteristic 2 finite
+ * field which has 2^{@code m} elements with
+ * polynomial basis.
+ * The reduction polynomial for this field is based
+ * on {@code rp} whose i-th bit corresponds to
+ * the i-th coefficient of the reduction polynomial.<p>
+ * Note: A valid reduction polynomial is either a
+ * trinomial (X^{@code m} + X^{@code k} + 1
+ * with {@code m} > {@code k} >= 1) or a
+ * pentanomial (X^{@code m} + X^{@code k3}
+ * + X^{@code k2} + X^{@code k1} + 1 with
+ * {@code m} > {@code k3} > {@code k2}
+ * > {@code k1} >= 1).
+ * @param m with 2^{@code m} being the number of elements.
+ * @param rp the BigInteger whose i-th bit corresponds to
+ * the i-th coefficient of the reduction polynomial.
+ * @exception NullPointerException if {@code rp} is null.
+ * @exception IllegalArgumentException if {@code m}
+ * is not positive, or {@code rp} does not represent
+ * a valid reduction polynomial.
+ */
+ public ECFieldF2m(int m, BigInteger rp) {
+ // check m and rp
+ this.m = m;
+ this.rp = rp;
+ if (m <= 0) {
+ throw new IllegalArgumentException("m is not positive");
+ }
+ int bitCount = this.rp.bitCount();
+ if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
+ ((bitCount != 3) && (bitCount != 5))) {
+ throw new IllegalArgumentException
+ ("rp does not represent a valid reduction polynomial");
+ }
+ // convert rp into ks
+ BigInteger temp = this.rp.clearBit(0).clearBit(m);
+ this.ks = new int[bitCount-2];
+ for (int i = this.ks.length-1; i >= 0; i--) {
+ int index = temp.getLowestSetBit();
+ this.ks[i] = index;
+ temp = temp.clearBit(index);
+ }
+ }
+
+ /**
+ * Creates an elliptic curve characteristic 2 finite
+ * field which has 2^{@code m} elements with
+ * polynomial basis. The reduction polynomial for this
+ * field is based on {@code ks} whose content
+ * contains the order of the middle term(s) of the
+ * reduction polynomial.
+ * Note: A valid reduction polynomial is either a
+ * trinomial (X^{@code m} + X^{@code k} + 1
+ * with {@code m} > {@code k} >= 1) or a
+ * pentanomial (X^{@code m} + X^{@code k3}
+ * + X^{@code k2} + X^{@code k1} + 1 with
+ * {@code m} > {@code k3} > {@code k2}
+ * > {@code k1} >= 1), so {@code ks} should
+ * have length 1 or 3.
+ * @param m with 2^{@code m} being the number of elements.
+ * @param ks the order of the middle term(s) of the
+ * reduction polynomial. Contents of this array are copied
+ * to protect against subsequent modification.
+ * @exception NullPointerException if {@code ks} is null.
+ * @exception IllegalArgumentException if{@code m}
+ * is not positive, or the length of {@code ks}
+ * is neither 1 nor 3, or values in {@code ks}
+ * are not between {@code m}-1 and 1 (inclusive)
+ * and in descending order.
+ */
+ public ECFieldF2m(int m, int[] ks) {
+ // check m and ks
+ this.m = m;
+ this.ks = ks.clone();
+ if (m <= 0) {
+ throw new IllegalArgumentException("m is not positive");
+ }
+ if ((this.ks.length != 1) && (this.ks.length != 3)) {
+ throw new IllegalArgumentException
+ ("length of ks is neither 1 nor 3");
+ }
+ for (int i = 0; i < this.ks.length; i++) {
+ if ((this.ks[i] < 1) || (this.ks[i] > m-1)) {
+ throw new IllegalArgumentException
+ ("ks["+ i + "] is out of range");
+ }
+ if ((i != 0) && (this.ks[i] >= this.ks[i-1])) {
+ throw new IllegalArgumentException
+ ("values in ks are not in descending order");
+ }
+ }
+ // convert ks into rp
+ this.rp = BigInteger.ONE;
+ this.rp = rp.setBit(m);
+ for (int j = 0; j < this.ks.length; j++) {
+ rp = rp.setBit(this.ks[j]);
+ }
+ }
+
+ /**
+ * Returns the field size in bits which is {@code m}
+ * for this characteristic 2 finite field.
+ * @return the field size in bits.
+ */
+ public int getFieldSize() {
+ return m;
+ }
+
+ /**
+ * Returns the value {@code m} of this characteristic
+ * 2 finite field.
+ * @return {@code m} with 2^{@code m} being the
+ * number of elements.
+ */
+ public int getM() {
+ return m;
+ }
+
+ /**
+ * Returns a BigInteger whose i-th bit corresponds to the
+ * i-th coefficient of the reduction polynomial for polynomial
+ * basis or null for normal basis.
+ * @return a BigInteger whose i-th bit corresponds to the
+ * i-th coefficient of the reduction polynomial for polynomial
+ * basis or null for normal basis.
+ */
+ public BigInteger getReductionPolynomial() {
+ return rp;
+ }
+
+ /**
+ * Returns an integer array which contains the order of the
+ * middle term(s) of the reduction polynomial for polynomial
+ * basis or null for normal basis.
+ * @return an integer array which contains the order of the
+ * middle term(s) of the reduction polynomial for polynomial
+ * basis or null for normal basis. A new array is returned
+ * each time this method is called.
+ */
+ public int[] getMidTermsOfReductionPolynomial() {
+ if (ks == null) {
+ return null;
+ } else {
+ return ks.clone();
+ }
+ }
+
+ /**
+ * Compares this finite field for equality with the
+ * specified object.
+ * @param obj the object to be compared.
+ * @return true if {@code obj} is an instance
+ * of ECFieldF2m and both {@code m} and the reduction
+ * polynomial match, false otherwise.
+ */
+ public boolean equals(Object obj) {
+ if (this == obj) return true;
+ if (obj instanceof ECFieldF2m) {
+ // no need to compare rp here since ks and rp
+ // should be equivalent
+ return ((m == ((ECFieldF2m)obj).m) &&
+ (Arrays.equals(ks, ((ECFieldF2m) obj).ks)));
+ }
+ return false;
+ }
+
+ /**
+ * Returns a hash code value for this characteristic 2
+ * finite field.
+ * @return a hash code value.
+ */
+ public int hashCode() {
+ int value = m << 5;
+ value += (rp==null? 0:rp.hashCode());
+ // no need to involve ks here since ks and rp
+ // should be equivalent.
+ return value;
+ }
+}