chacha20_poly1305.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2021 The FreeBSD Foundation
    5  *
    6  * This software was developed by Ararat River Consulting, LLC under
    7  * sponsorship from the FreeBSD Foundation.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   28  * SUCH DAMAGE.
   29  */
   30 
   31 #include <sys/endian.h>
   32 #include <crypto/chacha20_poly1305.h>
   33 #include <opencrypto/xform_enc.h>
   34 
   35 static const uint8_t zeroes[POLY1305_BLOCK_LEN];
   36 
   37 void
   38 chacha20_poly1305_encrypt(uint8_t *dst, const uint8_t *src,
   39     const size_t src_len, const uint8_t *aad, const size_t aad_len,
   40     const uint8_t *nonce, const size_t nonce_len, const uint8_t *key)
   41 {
   42         const struct enc_xform *exf;
   43         void *ctx;
   44         size_t resid, todo;
   45         uint64_t lengths[2];
   46 
   47         exf = &enc_xform_chacha20_poly1305;
   48         ctx = __builtin_alloca(exf->ctxsize);
   49         exf->setkey(ctx, key, CHACHA20_POLY1305_KEY);
   50         exf->reinit(ctx, nonce, nonce_len);
   51 
   52         exf->update(ctx, aad, aad_len);
   53         if (aad_len % POLY1305_BLOCK_LEN != 0)
   54                 exf->update(ctx, zeroes,
   55                     POLY1305_BLOCK_LEN - aad_len % POLY1305_BLOCK_LEN);
   56 
   57         resid = src_len;
   58         todo = rounddown2(resid, CHACHA20_NATIVE_BLOCK_LEN);
   59         if (todo > 0) {
   60                 exf->encrypt_multi(ctx, src, dst, todo);
   61                 exf->update(ctx, dst, todo);
   62                 src += todo;
   63                 dst += todo;
   64                 resid -= todo;
   65         }
   66         if (resid > 0) {
   67                 exf->encrypt_last(ctx, src, dst, resid);
   68                 exf->update(ctx, dst, resid);
   69                 dst += resid;
   70                 if (resid % POLY1305_BLOCK_LEN != 0)
   71                         exf->update(ctx, zeroes,
   72                             POLY1305_BLOCK_LEN - resid % POLY1305_BLOCK_LEN);
   73         }
   74 
   75         lengths[0] = htole64(aad_len);
   76         lengths[1] = htole64(src_len);
   77         exf->update(ctx, lengths, sizeof(lengths));
   78         exf->final(dst, ctx);
   79 
   80         explicit_bzero(ctx, exf->ctxsize);
   81         explicit_bzero(lengths, sizeof(lengths));
   82 }
   83 
   84 bool
   85 chacha20_poly1305_decrypt(uint8_t *dst, const uint8_t *src,
   86     const size_t src_len, const uint8_t *aad, const size_t aad_len,
   87     const uint8_t *nonce, const size_t nonce_len, const uint8_t *key)
   88 {
   89         const struct enc_xform *exf;
   90         void *ctx;
   91         size_t resid, todo;
   92         union {
   93                 uint64_t lengths[2];
   94                 char tag[POLY1305_HASH_LEN];
   95         } u;
   96         bool result;
   97 
   98         if (src_len < POLY1305_HASH_LEN)
   99                 return (false);
  100         resid = src_len - POLY1305_HASH_LEN;
  101 
  102         exf = &enc_xform_chacha20_poly1305;
  103         ctx = __builtin_alloca(exf->ctxsize);
  104         exf->setkey(ctx, key, CHACHA20_POLY1305_KEY);
  105         exf->reinit(ctx, nonce, nonce_len);
  106 
  107         exf->update(ctx, aad, aad_len);
  108         if (aad_len % POLY1305_BLOCK_LEN != 0)
  109                 exf->update(ctx, zeroes,
  110                     POLY1305_BLOCK_LEN - aad_len % POLY1305_BLOCK_LEN);
  111         exf->update(ctx, src, resid);
  112         if (resid % POLY1305_BLOCK_LEN != 0)
  113                 exf->update(ctx, zeroes,
  114                     POLY1305_BLOCK_LEN - resid % POLY1305_BLOCK_LEN);
  115 
  116         u.lengths[0] = htole64(aad_len);
  117         u.lengths[1] = htole64(resid);
  118         exf->update(ctx, u.lengths, sizeof(u.lengths));
  119         exf->final(u.tag, ctx);
  120         result = (timingsafe_bcmp(u.tag, src + resid, POLY1305_HASH_LEN) == 0);
  121         if (!result)
  122                 goto out;
  123 
  124         todo = rounddown2(resid, CHACHA20_NATIVE_BLOCK_LEN);
  125         if (todo > 0) {
  126                 exf->decrypt_multi(ctx, src, dst, todo);
  127                 src += todo;
  128                 dst += todo;
  129                 resid -= todo;
  130         }
  131         if (resid > 0)
  132                 exf->decrypt_last(ctx, src, dst, resid);
  133 
  134 out:
  135         explicit_bzero(ctx, exf->ctxsize);
  136         explicit_bzero(&u, sizeof(u));
  137         return (result);
  138 }
  139 
  140 void
  141 xchacha20_poly1305_encrypt(uint8_t *dst, const uint8_t *src,
  142     const size_t src_len, const uint8_t *aad, const size_t aad_len,
  143     const uint8_t *nonce, const uint8_t *key)
  144 {
  145         const struct enc_xform *exf;
  146         void *ctx;
  147         size_t resid, todo;
  148         uint64_t lengths[2];
  149 
  150         exf = &enc_xform_xchacha20_poly1305;
  151         ctx = __builtin_alloca(exf->ctxsize);
  152         exf->setkey(ctx, key, XCHACHA20_POLY1305_KEY);
  153         exf->reinit(ctx, nonce, XCHACHA20_POLY1305_IV_LEN);
  154 
  155         exf->update(ctx, aad, aad_len);
  156         if (aad_len % POLY1305_BLOCK_LEN != 0)
  157                 exf->update(ctx, zeroes,
  158                     POLY1305_BLOCK_LEN - aad_len % POLY1305_BLOCK_LEN);
  159 
  160         resid = src_len;
  161         todo = rounddown2(resid, CHACHA20_NATIVE_BLOCK_LEN);
  162         if (todo > 0) {
  163                 exf->encrypt_multi(ctx, src, dst, todo);
  164                 exf->update(ctx, dst, todo);
  165                 src += todo;
  166                 dst += todo;
  167                 resid -= todo;
  168         }
  169         if (resid > 0) {
  170                 exf->encrypt_last(ctx, src, dst, resid);
  171                 exf->update(ctx, dst, resid);
  172                 dst += resid;
  173                 if (resid % POLY1305_BLOCK_LEN != 0)
  174                         exf->update(ctx, zeroes,
  175                             POLY1305_BLOCK_LEN - resid % POLY1305_BLOCK_LEN);
  176         }
  177 
  178         lengths[0] = htole64(aad_len);
  179         lengths[1] = htole64(src_len);
  180         exf->update(ctx, lengths, sizeof(lengths));
  181         exf->final(dst, ctx);
  182 
  183         explicit_bzero(ctx, exf->ctxsize);
  184         explicit_bzero(lengths, sizeof(lengths));
  185 }
  186 
  187 bool
  188 xchacha20_poly1305_decrypt(uint8_t *dst, const uint8_t *src,
  189     const size_t src_len, const uint8_t *aad, const size_t aad_len,
  190     const uint8_t *nonce, const uint8_t *key)
  191 {
  192         const struct enc_xform *exf;
  193         void *ctx;
  194         size_t resid, todo;
  195         union {
  196                 uint64_t lengths[2];
  197                 char tag[POLY1305_HASH_LEN];
  198         } u;
  199         bool result;
  200 
  201         if (src_len < POLY1305_HASH_LEN)
  202                 return (false);
  203         resid = src_len - POLY1305_HASH_LEN;
  204 
  205         exf = &enc_xform_xchacha20_poly1305;
  206         ctx = __builtin_alloca(exf->ctxsize);
  207         exf->setkey(ctx, key, XCHACHA20_POLY1305_KEY);
  208         exf->reinit(ctx, nonce, XCHACHA20_POLY1305_IV_LEN);
  209 
  210         exf->update(ctx, aad, aad_len);
  211         if (aad_len % POLY1305_BLOCK_LEN != 0)
  212                 exf->update(ctx, zeroes,
  213                     POLY1305_BLOCK_LEN - aad_len % POLY1305_BLOCK_LEN);
  214         exf->update(ctx, src, resid);
  215         if (resid % POLY1305_BLOCK_LEN != 0)
  216                 exf->update(ctx, zeroes,
  217                     POLY1305_BLOCK_LEN - resid % POLY1305_BLOCK_LEN);
  218 
  219         u.lengths[0] = htole64(aad_len);
  220         u.lengths[1] = htole64(resid);
  221         exf->update(ctx, u.lengths, sizeof(u.lengths));
  222         exf->final(u.tag, ctx);
  223         result = (timingsafe_bcmp(u.tag, src + resid, POLY1305_HASH_LEN) == 0);
  224         if (!result)
  225                 goto out;
  226 
  227         todo = rounddown2(resid, CHACHA20_NATIVE_BLOCK_LEN);
  228         if (todo > 0) {
  229                 exf->decrypt_multi(ctx, src, dst, todo);
  230                 src += todo;
  231                 dst += todo;
  232                 resid -= todo;
  233         }
  234         if (resid > 0)
  235                 exf->decrypt_last(ctx, src, dst, resid);
  236 
  237 out:
  238         explicit_bzero(ctx, exf->ctxsize);
  239         explicit_bzero(&u, sizeof(u));
  240         return (result);
  241 }

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FreeBSD/Linux Kernel Cross Reference sys/crypto/chacha20_poly1305.c

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sys/crypto/chacha20_poly1305.c