    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.codec.digest;
    018
    019import java.security.MessageDigest;
    020import java.security.NoSuchAlgorithmException;
    021import java.security.SecureRandom;
    022import java.util.Arrays;
    023import java.util.Random;
    024import java.util.concurrent.ThreadLocalRandom;
    025import java.util.regex.Matcher;
    026import java.util.regex.Pattern;
    027
    028import org.apache.commons.codec.Charsets;
    029
    030/**
    031 * SHA2-based Unix crypt implementation.
    032 * <p>
    033 * Based on the C implementation released into the Public Domain by Ulrich Drepper &lt;drepper@redhat.com&gt;
    034 * http://www.akkadia.org/drepper/SHA-crypt.txt
    035 * <p>
    036 * Conversion to Kotlin and from there to Java in 2012 by Christian Hammers &lt;ch@lathspell.de&gt; and likewise put
    037 * into the Public Domain.
    038 * <p>
    039 * This class is immutable and thread-safe.
    040 *
    041 * @since 1.7
    042 */
    043public class Sha2Crypt {
    044
    045    /** Default number of rounds if not explicitly specified. */
    046    private static final int ROUNDS_DEFAULT = 5000;
    047
    048    /** Maximum number of rounds. */
    049    private static final int ROUNDS_MAX = 999999999;
    050
    051    /** Minimum number of rounds. */
    052    private static final int ROUNDS_MIN = 1000;
    053
    054    /** Prefix for optional rounds specification. */
    055    private static final String ROUNDS_PREFIX = "rounds=";
    056
    057    /** The number of bytes the final hash value will have (SHA-256 variant). */
    058    private static final int SHA256_BLOCKSIZE = 32;
    059
    060    /** The prefixes that can be used to identify this crypt() variant (SHA-256). */
    061    static final String SHA256_PREFIX = "$5$";
    062
    063    /** The number of bytes the final hash value will have (SHA-512 variant). */
    064    private static final int SHA512_BLOCKSIZE = 64;
    065
    066    /** The prefixes that can be used to identify this crypt() variant (SHA-512). */
    067    static final String SHA512_PREFIX = "$6$";
    068
    069    /** The pattern to match valid salt values. */
    070    private static final Pattern SALT_PATTERN = Pattern
    071            .compile("^\\$([56])\\$(rounds=(\\d+)\\$)?([\\.\\/a-zA-Z0-9]{1,16}).*");
    072
    073    /**
    074     * Generates a libc crypt() compatible "$5$" hash value with random salt.
    075     * <p>
    076     * See {@link Crypt#crypt(String, String)} for details.
    077     * </p>
    078     * <p>
    079     * A salt is generated for you using {@link ThreadLocalRandom}; for more secure salts consider using
    080     * {@link SecureRandom} to generate your own salts and calling {@link #sha256Crypt(byte[], String)}.
    081     * </p>
    082     *
    083     * @param keyBytes
    084     *            plaintext to hash
    085     * @return complete hash value
    086     * @throws IllegalArgumentException
    087     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
    088     */
    089    public static String sha256Crypt(final byte[] keyBytes) {
    090        return sha256Crypt(keyBytes, null);
    091    }
    092
    093    /**
    094     * Generates a libc6 crypt() compatible "$5$" hash value.
    095     * <p>
    096     * See {@link Crypt#crypt(String, String)} for details.
    097     * </p>
    098     * @param keyBytes
    099     *            plaintext to hash
    100     * @param salt
    101     *            real salt value without prefix or "rounds=". The salt may be null, in which case a salt
    102     *            is generated for you using {@link SecureRandom}. If one does not want to use {@link SecureRandom},
    103     *            you can pass your own {@link Random} in {@link #sha256Crypt(byte[], String, Random)}.
    104     * @return complete hash value including salt
    105     * @throws IllegalArgumentException
    106     *             if the salt does not match the allowed pattern
    107     * @throws IllegalArgumentException
    108     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
    109     */
    110    public static String sha256Crypt(final byte[] keyBytes, String salt) {
    111        if (salt == null) {
    112            salt = SHA256_PREFIX + B64.getRandomSalt(8);
    113        }
    114        return sha2Crypt(keyBytes, salt, SHA256_PREFIX, SHA256_BLOCKSIZE, MessageDigestAlgorithms.SHA_256);
    115    }
    116
    117    /**
    118     * Generates a libc6 crypt() compatible "$5$" hash value.
    119     * <p>
    120     * See {@link Crypt#crypt(String, String)} for details.
    121     * </p>
    122     * @param keyBytes
    123     *            plaintext to hash
    124     * @param salt
    125     *            real salt value without prefix or "rounds=".
    126     * @param random
    127     *            the instance of {@link Random} to use for generating the salt. Consider using {@link SecureRandom}
    128     *            or {@link ThreadLocalRandom}.
    129     * @return complete hash value including salt
    130     * @throws IllegalArgumentException
    131     *             if the salt does not match the allowed pattern
    132     * @throws IllegalArgumentException
    133     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
    134     * @since 1.12
    135     */
    136    public static String sha256Crypt(final byte[] keyBytes, String salt, final Random random) {
    137        if (salt == null) {
    138            salt = SHA256_PREFIX + B64.getRandomSalt(8, random);
    139        }
    140        return sha2Crypt(keyBytes, salt, SHA256_PREFIX, SHA256_BLOCKSIZE, MessageDigestAlgorithms.SHA_256);
    141    }
    142
    143    /**
    144     * Generates a libc6 crypt() compatible "$5$" or "$6$" SHA2 based hash value.
    145     * <p>
    146     * This is a nearly line by line conversion of the original C function. The numbered comments are from the algorithm
    147     * description, the short C-style ones from the original C code and the ones with "Remark" from me.
    148     * <p>
    149     * See {@link Crypt#crypt(String, String)} for details.
    150     *
    151     * @param keyBytes
    152     *            plaintext to hash
    153     * @param salt
    154     *            real salt value without prefix or "rounds="; may not be null
    155     * @param saltPrefix
    156     *            either $5$ or $6$
    157     * @param blocksize
    158     *            a value that differs between $5$ and $6$
    159     * @param algorithm
    160     *            {@link MessageDigest} algorithm identifier string
    161     * @return complete hash value including prefix and salt
    162     * @throws IllegalArgumentException
    163     *             if the given salt is <code>null</code> or does not match the allowed pattern
    164     * @throws IllegalArgumentException
    165     *             when a {@link NoSuchAlgorithmException} is caught
    166     * @see MessageDigestAlgorithms
    167     */
    168    private static String sha2Crypt(final byte[] keyBytes, final String salt, final String saltPrefix,
    169            final int blocksize, final String algorithm) {
    170
    171        final int keyLen = keyBytes.length;
    172
    173        // Extracts effective salt and the number of rounds from the given salt.
    174        int rounds = ROUNDS_DEFAULT;
    175        boolean roundsCustom = false;
    176        if (salt == null) {
    177            throw new IllegalArgumentException("Salt must not be null");
    178        }
    179
    180        final Matcher m = SALT_PATTERN.matcher(salt);
    181        if (!m.find()) {
    182            throw new IllegalArgumentException("Invalid salt value: " + salt);
    183        }
    184        if (m.group(3) != null) {
    185            rounds = Integer.parseInt(m.group(3));
    186            rounds = Math.max(ROUNDS_MIN, Math.min(ROUNDS_MAX, rounds));
    187            roundsCustom = true;
    188        }
    189        final String saltString = m.group(4);
    190        final byte[] saltBytes = saltString.getBytes(Charsets.UTF_8);
    191        final int saltLen = saltBytes.length;
    192
    193        // 1. start digest A
    194        // Prepare for the real work.
    195        MessageDigest ctx = DigestUtils.getDigest(algorithm);
    196
    197        // 2. the password string is added to digest A
    198        /*
    199         * Add the key string.
    200         */
    201        ctx.update(keyBytes);
    202
    203        // 3. the salt string is added to digest A. This is just the salt string
    204        // itself without the enclosing '$', without the magic salt_prefix $5$ and
    205        // $6$ respectively and without the rounds=<N> specification.
    206        //
    207        // NB: the MD5 algorithm did add the $1$ salt_prefix. This is not deemed
    208        // necessary since it is a constant string and does not add security
    209        // and /possibly/ allows a plain text attack. Since the rounds=<N>
    210        // specification should never be added this would also create an
    211        // inconsistency.
    212        /*
    213         * The last part is the salt string. This must be at most 16 characters and it ends at the first `$' character
    214         * (for compatibility with existing implementations).
    215         */
    216        ctx.update(saltBytes);
    217
    218        // 4. start digest B
    219        /*
    220         * Compute alternate sha512 sum with input KEY, SALT, and KEY. The final result will be added to the first
    221         * context.
    222         */
    223        MessageDigest altCtx = DigestUtils.getDigest(algorithm);
    224
    225        // 5. add the password to digest B
    226        /*
    227         * Add key.
    228         */
    229        altCtx.update(keyBytes);
    230
    231        // 6. add the salt string to digest B
    232        /*
    233         * Add salt.
    234         */
    235        altCtx.update(saltBytes);
    236
    237        // 7. add the password again to digest B
    238        /*
    239         * Add key again.
    240         */
    241        altCtx.update(keyBytes);
    242
    243        // 8. finish digest B
    244        /*
    245         * Now get result of this (32 bytes) and add it to the other context.
    246         */
    247        byte[] altResult = altCtx.digest();
    248
    249        // 9. For each block of 32 or 64 bytes in the password string (excluding
    250        // the terminating NUL in the C representation), add digest B to digest A
    251        /*
    252         * Add for any character in the key one byte of the alternate sum.
    253         */
    254        /*
    255         * (Remark: the C code comment seems wrong for key length > 32!)
    256         */
    257        int cnt = keyBytes.length;
    258        while (cnt > blocksize) {
    259            ctx.update(altResult, 0, blocksize);
    260            cnt -= blocksize;
    261        }
    262
    263        // 10. For the remaining N bytes of the password string add the first
    264        // N bytes of digest B to digest A
    265        ctx.update(altResult, 0, cnt);
    266
    267        // 11. For each bit of the binary representation of the length of the
    268        // password string up to and including the highest 1-digit, starting
    269        // from to lowest bit position (numeric value 1):
    270        //
    271        // a) for a 1-digit add digest B to digest A
    272        //
    273        // b) for a 0-digit add the password string
    274        //
    275        // NB: this step differs significantly from the MD5 algorithm. It
    276        // adds more randomness.
    277        /*
    278         * Take the binary representation of the length of the key and for every 1 add the alternate sum, for every 0
    279         * the key.
    280         */
    281        cnt = keyBytes.length;
    282        while (cnt > 0) {
    283            if ((cnt & 1) != 0) {
    284                ctx.update(altResult, 0, blocksize);
    285            } else {
    286                ctx.update(keyBytes);
    287            }
    288            cnt >>= 1;
    289        }
    290
    291        // 12. finish digest A
    292        /*
    293         * Create intermediate result.
    294         */
    295        altResult = ctx.digest();
    296
    297        // 13. start digest DP
    298        /*
    299         * Start computation of P byte sequence.
    300         */
    301        altCtx = DigestUtils.getDigest(algorithm);
    302
    303        // 14. for every byte in the password (excluding the terminating NUL byte
    304        // in the C representation of the string)
    305        //
    306        // add the password to digest DP
    307        /*
    308         * For every character in the password add the entire password.
    309         */
    310        for (int i = 1; i <= keyLen; i++) {
    311            altCtx.update(keyBytes);
    312        }
    313
    314        // 15. finish digest DP
    315        /*
    316         * Finish the digest.
    317         */
    318        byte[] tempResult = altCtx.digest();
    319
    320        // 16. produce byte sequence P of the same length as the password where
    321        //
    322        // a) for each block of 32 or 64 bytes of length of the password string
    323        // the entire digest DP is used
    324        //
    325        // b) for the remaining N (up to 31 or 63) bytes use the first N
    326        // bytes of digest DP
    327        /*
    328         * Create byte sequence P.
    329         */
    330        final byte[] pBytes = new byte[keyLen];
    331        int cp = 0;
    332        while (cp < keyLen - blocksize) {
    333            System.arraycopy(tempResult, 0, pBytes, cp, blocksize);
    334            cp += blocksize;
    335        }
    336        System.arraycopy(tempResult, 0, pBytes, cp, keyLen - cp);
    337
    338        // 17. start digest DS
    339        /*
    340         * Start computation of S byte sequence.
    341         */
    342        altCtx = DigestUtils.getDigest(algorithm);
    343
    344        // 18. repeast the following 16+A[0] times, where A[0] represents the first
    345        // byte in digest A interpreted as an 8-bit unsigned value
    346        //
    347        // add the salt to digest DS
    348        /*
    349         * For every character in the password add the entire password.
    350         */
    351        for (int i = 1; i <= 16 + (altResult[0] & 0xff); i++) {
    352            altCtx.update(saltBytes);
    353        }
    354
    355        // 19. finish digest DS
    356        /*
    357         * Finish the digest.
    358         */
    359        tempResult = altCtx.digest();
    360
    361        // 20. produce byte sequence S of the same length as the salt string where
    362        //
    363        // a) for each block of 32 or 64 bytes of length of the salt string
    364        // the entire digest DS is used
    365        //
    366        // b) for the remaining N (up to 31 or 63) bytes use the first N
    367        // bytes of digest DS
    368        /*
    369         * Create byte sequence S.
    370         */
    371        // Remark: The salt is limited to 16 chars, how does this make sense?
    372        final byte[] sBytes = new byte[saltLen];
    373        cp = 0;
    374        while (cp < saltLen - blocksize) {
    375            System.arraycopy(tempResult, 0, sBytes, cp, blocksize);
    376            cp += blocksize;
    377        }
    378        System.arraycopy(tempResult, 0, sBytes, cp, saltLen - cp);
    379
    380        // 21. repeat a loop according to the number specified in the rounds=<N>
    381        // specification in the salt (or the default value if none is
    382        // present). Each round is numbered, starting with 0 and up to N-1.
    383        //
    384        // The loop uses a digest as input. In the first round it is the
    385        // digest produced in step 12. In the latter steps it is the digest
    386        // produced in step 21.h. The following text uses the notation
    387        // "digest A/C" to describe this behavior.
    388        /*
    389         * Repeatedly run the collected hash value through sha512 to burn CPU cycles.
    390         */
    391        for (int i = 0; i <= rounds - 1; i++) {
    392            // a) start digest C
    393            /*
    394             * New context.
    395             */
    396            ctx = DigestUtils.getDigest(algorithm);
    397
    398            // b) for odd round numbers add the byte sequense P to digest C
    399            // c) for even round numbers add digest A/C
    400            /*
    401             * Add key or last result.
    402             */
    403            if ((i & 1) != 0) {
    404                ctx.update(pBytes, 0, keyLen);
    405            } else {
    406                ctx.update(altResult, 0, blocksize);
    407            }
    408
    409            // d) for all round numbers not divisible by 3 add the byte sequence S
    410            /*
    411             * Add salt for numbers not divisible by 3.
    412             */
    413            if (i % 3 != 0) {
    414                ctx.update(sBytes, 0, saltLen);
    415            }
    416
    417            // e) for all round numbers not divisible by 7 add the byte sequence P
    418            /*
    419             * Add key for numbers not divisible by 7.
    420             */
    421            if (i % 7 != 0) {
    422                ctx.update(pBytes, 0, keyLen);
    423            }
    424
    425            // f) for odd round numbers add digest A/C
    426            // g) for even round numbers add the byte sequence P
    427            /*
    428             * Add key or last result.
    429             */
    430            if ((i & 1) != 0) {
    431                ctx.update(altResult, 0, blocksize);
    432            } else {
    433                ctx.update(pBytes, 0, keyLen);
    434            }
    435
    436            // h) finish digest C.
    437            /*
    438             * Create intermediate result.
    439             */
    440            altResult = ctx.digest();
    441        }
    442
    443        // 22. Produce the output string. This is an ASCII string of the maximum
    444        // size specified above, consisting of multiple pieces:
    445        //
    446        // a) the salt salt_prefix, $5$ or $6$ respectively
    447        //
    448        // b) the rounds=<N> specification, if one was present in the input
    449        // salt string. A trailing '$' is added in this case to separate
    450        // the rounds specification from the following text.
    451        //
    452        // c) the salt string truncated to 16 characters
    453        //
    454        // d) a '$' character
    455        /*
    456         * Now we can construct the result string. It consists of three parts.
    457         */
    458        final StringBuilder buffer = new StringBuilder(saltPrefix);
    459        if (roundsCustom) {
    460            buffer.append(ROUNDS_PREFIX);
    461            buffer.append(rounds);
    462            buffer.append("$");
    463        }
    464        buffer.append(saltString);
    465        buffer.append("$");
    466
    467        // e) the base-64 encoded final C digest. The encoding used is as
    468        // follows:
    469        // [...]
    470        //
    471        // Each group of three bytes from the digest produces four
    472        // characters as output:
    473        //
    474        // 1. character: the six low bits of the first byte
    475        // 2. character: the two high bits of the first byte and the
    476        // four low bytes from the second byte
    477        // 3. character: the four high bytes from the second byte and
    478        // the two low bits from the third byte
    479        // 4. character: the six high bits from the third byte
    480        //
    481        // The groups of three bytes are as follows (in this sequence).
    482        // These are the indices into the byte array containing the
    483        // digest, starting with index 0. For the last group there are
    484        // not enough bytes left in the digest and the value zero is used
    485        // in its place. This group also produces only three or two
    486        // characters as output for SHA-512 and SHA-512 respectively.
    487
    488        // This was just a safeguard in the C implementation:
    489        // int buflen = salt_prefix.length() - 1 + ROUNDS_PREFIX.length() + 9 + 1 + salt_string.length() + 1 + 86 + 1;
    490
    491        if (blocksize == 32) {
    492            B64.b64from24bit(altResult[0], altResult[10], altResult[20], 4, buffer);
    493            B64.b64from24bit(altResult[21], altResult[1], altResult[11], 4, buffer);
    494            B64.b64from24bit(altResult[12], altResult[22], altResult[2], 4, buffer);
    495            B64.b64from24bit(altResult[3], altResult[13], altResult[23], 4, buffer);
    496            B64.b64from24bit(altResult[24], altResult[4], altResult[14], 4, buffer);
    497            B64.b64from24bit(altResult[15], altResult[25], altResult[5], 4, buffer);
    498            B64.b64from24bit(altResult[6], altResult[16], altResult[26], 4, buffer);
    499            B64.b64from24bit(altResult[27], altResult[7], altResult[17], 4, buffer);
    500            B64.b64from24bit(altResult[18], altResult[28], altResult[8], 4, buffer);
    501            B64.b64from24bit(altResult[9], altResult[19], altResult[29], 4, buffer);
    502            B64.b64from24bit((byte) 0, altResult[31], altResult[30], 3, buffer);
    503        } else {
    504            B64.b64from24bit(altResult[0], altResult[21], altResult[42], 4, buffer);
    505            B64.b64from24bit(altResult[22], altResult[43], altResult[1], 4, buffer);
    506            B64.b64from24bit(altResult[44], altResult[2], altResult[23], 4, buffer);
    507            B64.b64from24bit(altResult[3], altResult[24], altResult[45], 4, buffer);
    508            B64.b64from24bit(altResult[25], altResult[46], altResult[4], 4, buffer);
    509            B64.b64from24bit(altResult[47], altResult[5], altResult[26], 4, buffer);
    510            B64.b64from24bit(altResult[6], altResult[27], altResult[48], 4, buffer);
    511            B64.b64from24bit(altResult[28], altResult[49], altResult[7], 4, buffer);
    512            B64.b64from24bit(altResult[50], altResult[8], altResult[29], 4, buffer);
    513            B64.b64from24bit(altResult[9], altResult[30], altResult[51], 4, buffer);
    514            B64.b64from24bit(altResult[31], altResult[52], altResult[10], 4, buffer);
    515            B64.b64from24bit(altResult[53], altResult[11], altResult[32], 4, buffer);
    516            B64.b64from24bit(altResult[12], altResult[33], altResult[54], 4, buffer);
    517            B64.b64from24bit(altResult[34], altResult[55], altResult[13], 4, buffer);
    518            B64.b64from24bit(altResult[56], altResult[14], altResult[35], 4, buffer);
    519            B64.b64from24bit(altResult[15], altResult[36], altResult[57], 4, buffer);
    520            B64.b64from24bit(altResult[37], altResult[58], altResult[16], 4, buffer);
    521            B64.b64from24bit(altResult[59], altResult[17], altResult[38], 4, buffer);
    522            B64.b64from24bit(altResult[18], altResult[39], altResult[60], 4, buffer);
    523            B64.b64from24bit(altResult[40], altResult[61], altResult[19], 4, buffer);
    524            B64.b64from24bit(altResult[62], altResult[20], altResult[41], 4, buffer);
    525            B64.b64from24bit((byte) 0, (byte) 0, altResult[63], 2, buffer);
    526        }
    527
    528        /*
    529         * Clear the buffer for the intermediate result so that people attaching to processes or reading core dumps
    530         * cannot get any information.
    531         */
    532        // Is there a better way to do this with the JVM?
    533        Arrays.fill(tempResult, (byte) 0);
    534        Arrays.fill(pBytes, (byte) 0);
    535        Arrays.fill(sBytes, (byte) 0);
    536        ctx.reset();
    537        altCtx.reset();
    538        Arrays.fill(keyBytes, (byte) 0);
    539        Arrays.fill(saltBytes, (byte) 0);
    540
    541        return buffer.toString();
    542    }
    543
    544    /**
    545     * Generates a libc crypt() compatible "$6$" hash value with random salt.
    546     * <p>
    547     * See {@link Crypt#crypt(String, String)} for details.
    548     * </p>
    549     * <p>
    550     * A salt is generated for you using {@link ThreadLocalRandom}; for more secure salts consider using
    551     * {@link SecureRandom} to generate your own salts and calling {@link #sha512Crypt(byte[], String)}.
    552     * </p>
    553     *
    554     * @param keyBytes
    555     *            plaintext to hash
    556     * @return complete hash value
    557     * @throws IllegalArgumentException
    558     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
    559     */
    560    public static String sha512Crypt(final byte[] keyBytes) {
    561        return sha512Crypt(keyBytes, null);
    562    }
    563
    564    /**
    565     * Generates a libc6 crypt() compatible "$6$" hash value.
    566     * <p>
    567     * See {@link Crypt#crypt(String, String)} for details.
    568     * </p>
    569     * @param keyBytes
    570     *            plaintext to hash
    571     * @param salt
    572     *            real salt value without prefix or "rounds=". The salt may be null, in which case a salt is generated
    573     *            for you using {@link SecureRandom}; if you want to use a {@link Random} object other than
    574     *            {@link SecureRandom} then we suggest you provide it using
    575     *            {@link #sha512Crypt(byte[], String, Random)}.
    576     * @return complete hash value including salt
    577     * @throws IllegalArgumentException
    578     *             if the salt does not match the allowed pattern
    579     * @throws IllegalArgumentException
    580     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
    581     */
    582    public static String sha512Crypt(final byte[] keyBytes, String salt) {
    583        if (salt == null) {
    584            salt = SHA512_PREFIX + B64.getRandomSalt(8);
    585        }
    586        return sha2Crypt(keyBytes, salt, SHA512_PREFIX, SHA512_BLOCKSIZE, MessageDigestAlgorithms.SHA_512);
    587    }
    588
    589
    590
    591    /**
    592     * Generates a libc6 crypt() compatible "$6$" hash value.
    593     * <p>
    594     * See {@link Crypt#crypt(String, String)} for details.
    595     * </p>
    596     * @param keyBytes
    597     *            plaintext to hash
    598     * @param salt
    599     *            real salt value without prefix or "rounds=". The salt may be null, in which case a salt
    600     *            is generated for you using {@link ThreadLocalRandom}; for more secure salts consider using
    601     *            {@link SecureRandom} to generate your own salts.
    602     * @param random
    603     *            the instance of {@link Random} to use for generating the salt. Consider using {@link SecureRandom}
    604     *            or {@link ThreadLocalRandom}.
    605     * @return complete hash value including salt
    606     * @throws IllegalArgumentException
    607     *             if the salt does not match the allowed pattern
    608     * @throws IllegalArgumentException
    609     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
    610     * @since 1.12
    611     */
    612    public static String sha512Crypt(final byte[] keyBytes, String salt, final Random random) {
    613        if (salt == null) {
    614            salt = SHA512_PREFIX + B64.getRandomSalt(8, random);
    615        }
    616        return sha2Crypt(keyBytes, salt, SHA512_PREFIX, SHA512_BLOCKSIZE, MessageDigestAlgorithms.SHA_512);
    617    }
    618}