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/*
* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
static void
gen_chapol_init(br_sslrec_chapol_context *cc,
br_chacha20_run ichacha, br_poly1305_run ipoly,
const void *key, const void *iv)
{
cc->seq = 0;
cc->ichacha = ichacha;
cc->ipoly = ipoly;
memcpy(cc->key, key, sizeof cc->key);
memcpy(cc->iv, iv, sizeof cc->iv);
}
static void
gen_chapol_process(br_sslrec_chapol_context *cc,
int record_type, unsigned version, void *data, size_t len,
void *tag, int encrypt)
{
unsigned char header[13];
unsigned char nonce[12];
uint64_t seq;
size_t u;
seq = cc->seq ++;
br_enc64be(header, seq);
header[8] = (unsigned char)record_type;
br_enc16be(header + 9, version);
br_enc16be(header + 11, len);
memcpy(nonce, cc->iv, 12);
for (u = 0; u < 8; u ++) {
nonce[11 - u] ^= (unsigned char)seq;
seq >>= 8;
}
cc->ipoly(cc->key, nonce, data, len, header, sizeof header,
tag, cc->ichacha, encrypt);
}
static void
in_chapol_init(br_sslrec_chapol_context *cc,
br_chacha20_run ichacha, br_poly1305_run ipoly,
const void *key, const void *iv)
{
cc->vtable.in = &br_sslrec_in_chapol_vtable;
gen_chapol_init(cc, ichacha, ipoly, key, iv);
}
static int
chapol_check_length(const br_sslrec_chapol_context *cc, size_t rlen)
{
/*
* Overhead is just the authentication tag (16 bytes).
*/
(void)cc;
return rlen >= 16 && rlen <= (16384 + 16);
}
static unsigned char *
chapol_decrypt(br_sslrec_chapol_context *cc,
int record_type, unsigned version, void *data, size_t *data_len)
{
unsigned char *buf;
size_t u, len;
unsigned char tag[16];
unsigned bad;
buf = data;
len = *data_len - 16;
gen_chapol_process(cc, record_type, version, buf, len, tag, 0);
bad = 0;
for (u = 0; u < 16; u ++) {
bad |= tag[u] ^ buf[len + u];
}
if (bad) {
return NULL;
}
*data_len = len;
return buf;
}
/* see bearssl_ssl.h */
const br_sslrec_in_chapol_class br_sslrec_in_chapol_vtable = {
{
sizeof(br_sslrec_chapol_context),
(int (*)(const br_sslrec_in_class *const *, size_t))
&chapol_check_length,
(unsigned char *(*)(const br_sslrec_in_class **,
int, unsigned, void *, size_t *))
&chapol_decrypt
},
(void (*)(const br_sslrec_in_chapol_class **,
br_chacha20_run, br_poly1305_run,
const void *, const void *))
&in_chapol_init
};
static void
out_chapol_init(br_sslrec_chapol_context *cc,
br_chacha20_run ichacha, br_poly1305_run ipoly,
const void *key, const void *iv)
{
cc->vtable.out = &br_sslrec_out_chapol_vtable;
gen_chapol_init(cc, ichacha, ipoly, key, iv);
}
static void
chapol_max_plaintext(const br_sslrec_chapol_context *cc,
size_t *start, size_t *end)
{
size_t len;
(void)cc;
len = *end - *start - 16;
if (len > 16384) {
len = 16384;
}
*end = *start + len;
}
static unsigned char *
chapol_encrypt(br_sslrec_chapol_context *cc,
int record_type, unsigned version, void *data, size_t *data_len)
{
unsigned char *buf;
size_t len;
buf = data;
len = *data_len;
gen_chapol_process(cc, record_type, version, buf, len, buf + len, 1);
buf -= 5;
buf[0] = (unsigned char)record_type;
br_enc16be(buf + 1, version);
br_enc16be(buf + 3, len + 16);
*data_len = len + 21;
return buf;
}
/* see bearssl_ssl.h */
const br_sslrec_out_chapol_class br_sslrec_out_chapol_vtable = {
{
sizeof(br_sslrec_chapol_context),
(void (*)(const br_sslrec_out_class *const *,
size_t *, size_t *))
&chapol_max_plaintext,
(unsigned char *(*)(const br_sslrec_out_class **,
int, unsigned, void *, size_t *))
&chapol_encrypt
},
(void (*)(const br_sslrec_out_chapol_class **,
br_chacha20_run, br_poly1305_run,
const void *, const void *))
&out_chapol_init
};
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