_ Git - BearSSL/blob - src/ssl/ssl_rec_chapol.c

   1 /*
   2  * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining
   5  * a copy of this software and associated documentation files (the
   6  * "Software"), to deal in the Software without restriction, including
   7  * without limitation the rights to use, copy, modify, merge, publish,
   8  * distribute, sublicense, and/or sell copies of the Software, and to
   9  * permit persons to whom the Software is furnished to do so, subject to
  10  * the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  19  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  20  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  21  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22  * SOFTWARE.
  23  */
  24
  25 #include "inner.h"
  26
  27 static void
  28 gen_chapol_init(br_sslrec_chapol_context *cc,
  29         br_chacha20_run ichacha, br_poly1305_run ipoly,
  30         const void *key, const void *iv)
  31 {
  32         cc->seq = 0;
  33         cc->ichacha = ichacha;
  34         cc->ipoly = ipoly;
  35         memcpy(cc->key, key, sizeof cc->key);
  36         memcpy(cc->iv, iv, sizeof cc->iv);
  37 }
  38
  39 static void
  40 gen_chapol_process(br_sslrec_chapol_context *cc,
  41         int record_type, unsigned version, void *data, size_t len,
  42         void *tag, int encrypt)
  43 {
  44         unsigned char header[13];
  45         unsigned char nonce[12];
  46         uint64_t seq;
  47         size_t u;
  48
  49         seq = cc->seq ++;
  50         br_enc64be(header, seq);
  51         header[8] = (unsigned char)record_type;
  52         br_enc16be(header + 9, version);
  53         br_enc16be(header + 11, len);
  54         memcpy(nonce, cc->iv, 12);
  55         for (u = 0; u < 8; u ++) {
  56                 nonce[11 - u] ^= (unsigned char)seq;
  57                 seq >>= 8;
  58         }
  59         cc->ipoly(cc->key, nonce, data, len, header, sizeof header,
  60                 tag, cc->ichacha, encrypt);
  61 }
  62
  63 static void
  64 in_chapol_init(br_sslrec_chapol_context *cc,
  65         br_chacha20_run ichacha, br_poly1305_run ipoly,
  66         const void *key, const void *iv)
  67 {
  68         cc->vtable.in = &br_sslrec_in_chapol_vtable;
  69         gen_chapol_init(cc, ichacha, ipoly, key, iv);
  70 }
  71
  72 static int
  73 chapol_check_length(const br_sslrec_chapol_context *cc, size_t rlen)
  74 {
  75         /*
  76          * Overhead is just the authentication tag (16 bytes).
  77          */
  78         (void)cc;
  79         return rlen >= 16 && rlen <= (16384 + 16);
  80 }
  81
  82 static unsigned char *
  83 chapol_decrypt(br_sslrec_chapol_context *cc,
  84         int record_type, unsigned version, void *data, size_t *data_len)
  85 {
  86         unsigned char *buf;
  87         size_t u, len;
  88         unsigned char tag[16];
  89         unsigned bad;
  90
  91         buf = data;
  92         len = *data_len - 16;
  93         gen_chapol_process(cc, record_type, version, buf, len, tag, 0);
  94         bad = 0;
  95         for (u = 0; u < 16; u ++) {
  96                 bad |= tag[u] ^ buf[len + u];
  97         }
  98         if (bad) {
  99                 return NULL;
 100         }
 101         *data_len = len;
 102         return buf;
 103 }
 104
 105 /* see bearssl_ssl.h */
 106 const br_sslrec_in_chapol_class br_sslrec_in_chapol_vtable = {
 107         {
 108                 sizeof(br_sslrec_chapol_context),
 109                 (int (*)(const br_sslrec_in_class *const *, size_t))
 110                         &chapol_check_length,
 111                 (unsigned char *(*)(const br_sslrec_in_class **,
 112                         int, unsigned, void *, size_t *))
 113                         &chapol_decrypt
 114         },
 115         (void (*)(const br_sslrec_in_chapol_class **,
 116                 br_chacha20_run, br_poly1305_run,
 117                 const void *, const void *))
 118                 &in_chapol_init
 119 };
 120
 121 static void
 122 out_chapol_init(br_sslrec_chapol_context *cc,
 123         br_chacha20_run ichacha, br_poly1305_run ipoly,
 124         const void *key, const void *iv)
 125 {
 126         cc->vtable.out = &br_sslrec_out_chapol_vtable;
 127         gen_chapol_init(cc, ichacha, ipoly, key, iv);
 128 }
 129
 130 static void
 131 chapol_max_plaintext(const br_sslrec_chapol_context *cc,
 132         size_t *start, size_t *end)
 133 {
 134         size_t len;
 135
 136         (void)cc;
 137         len = *end - *start - 16;
 138         if (len > 16384) {
 139                 len = 16384;
 140         }
 141         *end = *start + len;
 142 }
 143
 144 static unsigned char *
 145 chapol_encrypt(br_sslrec_chapol_context *cc,
 146         int record_type, unsigned version, void *data, size_t *data_len)
 147 {
 148         unsigned char *buf;
 149         size_t len;
 150
 151         buf = data;
 152         len = *data_len;
 153         gen_chapol_process(cc, record_type, version, buf, len, buf + len, 1);
 154         buf -= 5;
 155         buf[0] = (unsigned char)record_type;
 156         br_enc16be(buf + 1, version);
 157         br_enc16be(buf + 3, len + 16);
 158         *data_len = len + 21;
 159         return buf;
 160 }
 161
 162 /* see bearssl_ssl.h */
 163 const br_sslrec_out_chapol_class br_sslrec_out_chapol_vtable = {
 164         {
 165                 sizeof(br_sslrec_chapol_context),
 166                 (void (*)(const br_sslrec_out_class *const *,
 167                         size_t *, size_t *))
 168                         &chapol_max_plaintext,
 169                 (unsigned char *(*)(const br_sslrec_out_class **,
 170                         int, unsigned, void *, size_t *))
 171                         &chapol_encrypt
 172         },
 173         (void (*)(const br_sslrec_out_chapol_class **,
 174                 br_chacha20_run, br_poly1305_run,
 175                 const void *, const void *))
 176                 &out_chapol_init
 177 };