/*

 * Copyright (c) 2019, 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.

 *

 * 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 sun.security.rsa;

import java.math.BigInteger;

import java.security.*;

import java.security.spec.AlgorithmParameterSpec;

import java.security.spec.RSAKeyGenParameterSpec;

import sun.security.x509.AlgorithmId;

import static sun.security.rsa.RSAUtil.KeyType;

/**

 * A fake RSA keypair generation.

 */

public abstract class RSAKeyPairGenerator extends KeyPairGeneratorSpi {

    // public exponent to use

    private BigInteger publicExponent;

    // size of the key to generate, >= RSAKeyFactory.MIN_MODLEN

    private int keySize;

    private final KeyType type;

    private AlgorithmId rsaId;

    RSAKeyPairGenerator(KeyType type, int defKeySize) {

        this.type = type;

        // initialize to default in case the app does not call initialize()

        initialize(defKeySize, null);

    }

    // initialize the generator. See JCA doc

    public void initialize(int keySize, SecureRandom random) {

        try {

            initialize(new RSAKeyGenParameterSpec(keySize,

                    RSAKeyGenParameterSpec.F4), random);

        } catch (InvalidAlgorithmParameterException iape) {

            throw new InvalidParameterException(iape.getMessage());

        }

    }

    // second initialize method. See JCA doc.

    public void initialize(AlgorithmParameterSpec params, SecureRandom random)

            throws InvalidAlgorithmParameterException {

        if (params instanceof RSAKeyGenParameterSpec == false) {

            throw new InvalidAlgorithmParameterException

                ("Params must be instance of RSAKeyGenParameterSpec");

        }

        RSAKeyGenParameterSpec rsaSpec = (RSAKeyGenParameterSpec)params;

        int tmpKeySize = rsaSpec.getKeysize();

        BigInteger tmpPublicExponent = rsaSpec.getPublicExponent();

        AlgorithmParameterSpec tmpParams = rsaSpec.getKeyParams();

        if (tmpPublicExponent == null) {

            tmpPublicExponent = RSAKeyGenParameterSpec.F4;

        } else {

            if (tmpPublicExponent.compareTo(RSAKeyGenParameterSpec.F0) < 0) {

                throw new InvalidAlgorithmParameterException

                        ("Public exponent must be 3 or larger");

            }

            if (tmpPublicExponent.bitLength() > tmpKeySize) {

                throw new InvalidAlgorithmParameterException

                        ("Public exponent must be smaller than key size");

            }

        }

        // do not allow unreasonably large key sizes, probably user error

        try {

            RSAKeyFactory.checkKeyLengths(tmpKeySize, tmpPublicExponent,

                512, 64 * 1024);

        } catch (InvalidKeyException e) {

            throw new InvalidAlgorithmParameterException(

                "Invalid key sizes", e);

        }

        try {

            this.rsaId = RSAUtil.createAlgorithmId(type, tmpParams);

        } catch (ProviderException e) {

            throw new InvalidAlgorithmParameterException(

                "Invalid key parameters", e);

        }

        this.keySize = tmpKeySize;

        this.publicExponent = tmpPublicExponent;

    }

    // generate the keypair. See JCA doc

    public KeyPair generateKeyPair() {

        // accommodate odd key sizes in case anybody wants to use them

        BigInteger e = publicExponent;

        if (!e.equals(RSAKeyGenParameterSpec.F4)) {

            throw new AssertionError("Only support F4 now");

        }

        BigInteger p, q, n;

        // Pre-calculated p and q for e == RSAKeyGenParameterSpec.F4

        switch (keySize) {

            case 1024:

                p = new BigInteger("1220491537800192366196661816910427"

                        + "2375185130493819649338056226264568132442590"

                        + "2306195110391300298681932797393339089272174"

                        + "24490645345596103420476757417659909");

                q = new BigInteger("8480533592205316739308384508307319"

                        + "3310632635895778398980504245932789486455154"

                        + "4265220956952343855842030266079089174423047"

                        + "7382175514060777025691485728713063");

                break;

            case 2048:

                p = new BigInteger("1600840041787354447543653385760927"

                        + "2642568308955833364523274045522752644800599"

                        + "8669541532595690224703734511692014533312515"

                        + "1867029838883431415692353449578487671384896"

                        + "6611685764860941767986520897595108597563035"

                        + "4023785639802607792535812062420427283857665"

                        + "9883578590844700707106157871508280052743363"

                        + "65749456332400771");

                q = new BigInteger("1303880717101677622201474394769850"

                        + "7257196073324816341282215626935164930077468"

                        + "5999131251387556761167658937349436378464220"

                        + "4831804147777472146628148336776639855791417"

                        + "3849903041999943901924899580268176393595653"

                        + "7357080543898614581363167420619163047562600"

                        + "6155574020606891195960345238780709194499010"

                        + "43652862954645301");

                break;

            case 3072:

                p = new BigInteger("2403380417344527161525447148950543"

                        + "9379802436047502603774623852967909282895900"

                        + "7474251859703715384817150107392592636129366"

                        + "5680725148417789414447073716354703692160825"

                        + "9910929198523923851672957013786423746474670"

                        + "5285365870313877239114930859096040034848729"

                        + "0251735848703378313724697081522892607625120"

                        + "0765531003751468146539682665307123591367928"

                        + "1883284784295069877414057796300484015307336"

                        + "5167008365209621810307777651197826810474895"

                        + "858836606799546054179898997210174885200767");

                q = new BigInteger("2046511893459993309772203642844931"

                        + "1853027469856467052942666265372903000702193"

                        + "7794121141028918655144044411085405243565188"

                        + "8318027937964509940322691121105328104450287"

                        + "0400405975394764523022670537180050051646095"

                        + "3320242109876620452477757629185501504625999"

                        + "8487187901577781067325277853462587849063313"

                        + "5364789330253471096755661110557598411108366"

                        + "1566266965711522070909440716658568303529454"

                        + "8075296935907088988560548322049196321207173"

                        + "136436923455192617031129191723631954025427");

                break;

            case 3073:

                p = new BigInteger("358024230418365680745725628188289"

                        + "996969857993064124357766607077169315932503"

                        + "907030633492082868150575329278637502167157"

                        + "345572819552678004302525872656665704012432"

                        + "644868036964802792468216554458209893873320"

                        + "297608885231998895441396822219845215463819"

                        + "216163684222596923153702349718019538798623"

                        + "793830598445085650304217449539016339429747"

                        + "385490484982419227549804698120223647408926"

                        + "021549912791440569127641517442362359166673"

                        + "430151753277549861070074076802118983202554"

                        + "7683523973");

                q = new BigInteger("169752169194244078720180277210205"

                        + "255207796420396114596943944148158798629671"

                        + "789863988428383183103705641694331073747120"

                        + "522505020908219489265190380712941311249155"

                        + "156834674079165492105570443486536740756291"

                        + "314279877766807786397193023304245520017295"

                        + "969248707516367324340822062886043618371887"

                        + "320492710434958863952407959935025922006108"

                        + "282752473898685457767312430894004833959025"

                        + "415996648289919841900071076314309778495245"

                        + "505026665971431792707247787031811654193145"

                        + "1044952887");

                break;

            case 4096:

                p = new BigInteger("2985635754414679487171962796211911"

                        + "1563710734938215274736352092606404045130913"

                        + "2477365484439939846705721840432140066578525"

                        + "0762327458086280430118434094733412377416194"

                        + "8736124795243564050755767519346747209606612"

                        + "5835460937739428885308798309679495432910469"

                        + "0294757621321446003970767164933974474924664"

                        + "1513767092845098947552598109657871041666676"

                        + "2945573325433283821164032766425479703026349"

                        + "9433641551427112483593214628620450175257586"

                        + "4350119143877183562692754400346175237007314"

                        + "7121580349193179272551363894896336921717843"

                        + "3734726842184251708799134654802475890197293"

                        + "9094908310578403843742664173424031260840446"

                        + "591633359364559754200663");

                q = new BigInteger("2279248439141087793789384816271625"

                        + "1304008816573950275844533962181244003563987"

                        + "6638461665174020058827698592331066726709304"

                        + "9231319346136709972639455506783245161859951"

                        + "6191872757335765533547033659834427437142631"

                        + "3801232751161907082392011429712327250253948"

                        + "6012497852063361866175243227579880020724881"

                        + "9393797645220239009219998518884396282407710"

                        + "7199202450846395844337846503427790307364624"

                        + "5124871273035872938616425951596065309519651"

                        + "1519189356431513094684173807318945903212527"

                        + "7712469749366620048658571121822171067675915"

                        + "5479178304648399924549334007222294762969503"

                        + "5341584429803583589276956979963609078497238"

                        + "760757619468018224491053");

                break;

            case 7680:

                p = new BigInteger("7034022146817764608206409206476311"

                        + "1371065855827199565170055133179419153145313"

                        + "9446295819321510144417300286482767498463255"

                        + "3370362723164324606829434617977090251035572"

                        + "4237546099249090966627372485629853471350368"

                        + "1497807044971675189990783927066958945388379"

                        + "4004871857862380913954692362042250112646330"

                        + "0515873693830575810241740671573357342073942"

                        + "4924331206670599086552994426505996651481869"

                        + "2750320309695596383830444337180596058381417"

                        + "7804256675894755482917598033151085120879826"

                        + "5373459707672000040090469058320463160804122"

                        + "8041026671361647347262771363754358441620179"

                        + "3861076191970047581401830740749715862725492"

                        + "5750077182986169592435996668282677192000592"

                        + "8019204141383012670399208092972174321639234"

                        + "6398779487064860458178135981700487728919191"

                        + "2418625085287791733119321378648688730352488"

                        + "6446800847442687530322927871063574241918202"

                        + "1883228799435533794167861499482410970370569"

                        + "6964781912514810444018313637829915454156777"

                        + "4591735979781496237582756842195362757823524"

                        + "2054367976655738752756266147542536910268553"

                        + "7448833810249238249431673425245843356607647"

                        + "4372260685985882252621076435844355190011754"

                        + "0656637395317040751098009821385816878380790"

                        + "9017022563392158510700243843871343995665725"

                        + "9447");

                q = new BigInteger("7006097449483280289139842436346899"

                        + "9530483972793167261845287040200424598484519"

                        + "0516644904497480849788319004016685820778949"

                        + "8514891188272714344395538114013074460410497"

                        + "8359325044727263936454825245761418873141623"

                        + "2797767712619624879346520836103128457266811"

                        + "0175147598232556414901292143389437071453369"

                        + "4867355570712858957689566849950544938172174"

                        + "9136345403774445991224311311204082279382451"

                        + "1977673518543939329498617563049052032259503"

                        + "1057378839061411322975567618416093845144604"

                        + "4563500271329350225709899627798126176885843"

                        + "9953695524756659384424971651654225913916902"

                        + "7087953078966988666226779422822854729725410"

                        + "1118666318953891716194309185187152294057704"

                        + "2509582485250984938518224243061447485603856"

                        + "0197517312286511585545481984194518805766300"

                        + "7351141154720653351520788558277866920369211"

                        + "9269193267018615410395030712426882576851775"

                        + "9240726416572698143674385203349496226355950"

                        + "0327319442530888807531774734409411628435155"

                        + "6449625936156829175453919098709371623972260"

                        + "4090598351878256110255744263233419699486705"

                        + "3658219936031243191809689036438631617494147"

                        + "8183898954195399872571907981872765548994005"

                        + "0754996819683869837696561316479950526914796"

                        + "3613549619563212818369365543951734053135086"

                        + "8593");

                break;

            case 7681:

                p = new BigInteger("1051422012172516922972337796421710"

                        + "1479918158427421377774284533124281583092508"

                        + "4961153980854679659383249048667658521370629"

                        + "6404078819943386006431233653506112030196761"

                        + "7596078830067404622117784094070983115834842"

                        + "0487926993058767148294211654032287322495894"

                        + "1733666341539644761909820700670130074920230"

                        + "0423405253327351685101039824822997870642295"

                        + "8176417666723292317903368285439828460328413"

                        + "9578515412811253729224087502906626189200448"

                        + "4062549581079444644685394008569377879899377"

                        + "0578136407363616816108795867392262638913436"

                        + "2041457188733948013731661456602199370852579"

                        + "2394583215214266552642082043674873685065171"

                        + "9053703728689139119006448644148961706358756"

                        + "0498696516029596534138345596800696824976461"

                        + "8461070371773003241093580622731426623849732"

                        + "8737707046931934781383331589291927520571138"

                        + "2759511573966362005294438252298268405782746"

                        + "9642105075721912120520774388679358659061825"

                        + "8867415333830751976884165265610029632416351"

                        + "6666642762305875140340531095190000199307531"

                        + "2186952558457690950270489966695323839026041"

                        + "0797018634946454573060304991245539422899112"

                        + "9312288231966690989900334936215870198735213"

                        + "6745631923445509394027128331099748294658904"

                        + "6303809606943116678969915369410846798143779"

                        + "89187");

                q = new BigInteger("8160183444544784072886152354850963"

                        + "2507221530634202707531181684048014518183560"

                        + "4586261698204521358487995639975786964316103"

                        + "5861955444259138806900123878887948650444640"

                        + "7062365744302695074634248387572850855758081"

                        + "9074631976865727985289995811413472254074432"

                        + "4751574514329862821405069035713821908598155"

                        + "5436571566703295992717666421591959121774983"

                        + "5913798632992394695663301960139778059658979"

                        + "4944466598070019481108421780314115410201334"

                        + "2925668957166258484312039121420100795544341"

                        + "5372918969907063685116069321551182817324799"

                        + "3347159610063964281388144113123539915925090"

                        + "2692309096312451442405059120315891913678403"

                        + "4977738880336169371406947347468157606390086"

                        + "3381587148478097717352225924672548657441771"

                        + "3887371520215341151934095945869956390140929"

                        + "3098286281540595154062683214111934217839063"

                        + "3309526631019699109621050440794920159910038"

                        + "3248965999877529393614116991972153758910967"

                        + "1712258745878268303349611893651932564447696"

                        + "9601760120187828039923387985032881949408596"

                        + "0689784023540256749586591441103043888423326"

                        + "3078541569639917739590630101701573133092711"

                        + "6157430583592378472242178997833136144409256"

                        + "3558220277370179546822023437190315852529873"

                        + "0831890147323301322699740037060134979740963"

                        + "4289");

                break;

            case 8192:

                p = new BigInteger("9821669838446774374944535804569858"

                        + "0553278885576950130485823829973470553571905"

                        + "3014418421996241500307589880457361653957913"

                        + "9176499436767288125182942994089196450118944"

                        + "8701794862752733776161684616570463744619126"

                        + "4981622564763630694110472008409561205704867"

                        + "0221819623405201369630462487520858670679048"

                        + "5854008441429858453634949980424333056803703"

                        + "1205609490778445762604050796894221725977551"

                        + "1428887194691696420765173256600200430067305"

                        + "4364524177041858044598166859757042904625691"

                        + "4292728453597609683799189454690202563236931"

                        + "8171122071288244573793276051041975005528757"

                        + "0228306442708182141334279133965507583927772"

                        + "9244311696220253059281524393613278272067808"

                        + "7017494446447670799055720358621918361716353"

                        + "5018317015764698318012095108914870478138809"

                        + "8204738169777192718869484177321870413838036"

                        + "8149216482968887382371881239714335470844573"

                        + "1862934371951394070111726593305334971041399"

                        + "5517260339034138718517336990212463882142363"

                        + "9154412320743552301967162100734381046548816"

                        + "3883737645359595416600487444018399886391071"

                        + "3777667222706059170707223589163679915863781"

                        + "4662302526078720977228426750718207481384357"

                        + "7918717041190413457052439016978578217755022"

                        + "7370720979516554707297685239584071755267452"

                        + "6021894842754355160100506065457679069228273"

                        + "95209345267367982516553449135291473361");

                q = new BigInteger("7902448465953646210110784092684896"

                        + "0265474424590294110174550047938700740921014"

                        + "1981650823416127449143596912363210790070524"

                        + "2903784112701128957948996730263815210531364"

                        + "0489145287401377007608600217628773627723381"

                        + "1194123533939872283952535576847014977682278"

                        + "9332064706645169741712060131540562788886577"

                        + "3762235020990267901959745687867018811088495"

                        + "3716021011509120447248882358515954471433808"

                        + "2782236662758287959413069553620728137831579"

                        + "2321174813204514354999978428741310035945405"

                        + "0226661395731921098764192439072425262100813"

                        + "9732949866553839713092238096261034339815187"

                        + "2832617055364163276140160068136296115910569"

                        + "9466440903693740716929166334256441926903849"

                        + "1082968246155177124035336609654226388424434"

                        + "5775783323612758615407928446164631651292743"

                        + "8428509642959278732826297890909454571009075"

                        + "7836191622138731918099379467912681177757761"

                        + "6141378131042432093843778753846726589215845"

                        + "7402160146427434508515156204064224022904659"

                        + "8645441448874409852211668374267341177082462"

                        + "7341410218867175406105046487057429530801973"

                        + "0931082058719258230993681115780999537424968"

                        + "2385515792331573549935317407789344892257264"

                        + "7464569110078675090194686816764429827739815"

                        + "0566036514181547634372488184242167294602000"

                        + "8232780963578241583529875079397308150506597"

                        + "37190564909892937290776929541076192569");

                break;

            default:

                throw new AssertionError("Unknown keySize " + keySize);

        }

        n = p.multiply(q);

        // phi = (p - 1) * (q - 1) must be relative prime to e

        // otherwise RSA just won't work ;-)

        BigInteger p1 = p.subtract(BigInteger.ONE);

        BigInteger q1 = q.subtract(BigInteger.ONE);

        BigInteger phi = p1.multiply(q1);

        // generate new p and q until they work. typically

        // the first try will succeed when using F4

        if (e.gcd(phi).equals(BigInteger.ONE) == false) {

            throw new AssertionError("Should not happen");

        }

        // private exponent d is the inverse of e mod phi

        BigInteger d = e.modInverse(phi);

        // 1st prime exponent pe = d mod (p - 1)

        BigInteger pe = d.mod(p1);

        // 2nd prime exponent qe = d mod (q - 1)

        BigInteger qe = d.mod(q1);

        // crt coefficient coeff is the inverse of q mod p

        BigInteger coeff = q.modInverse(p);

        try {

            PublicKey publicKey = new RSAPublicKeyImpl(rsaId, n, e);

            PrivateKey privateKey = new RSAPrivateCrtKeyImpl(

                    rsaId, n, e, d, p, q, pe, qe, coeff);

            return new KeyPair(publicKey, privateKey);

        } catch (InvalidKeyException exc) {

            // invalid key exception only thrown for keys < 512 bit,

            // will not happen here

            throw new RuntimeException(exc);

        }

    }

}