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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"
/* see bearssl_block.h */
void
br_aes_ct64_cbcdec_init(br_aes_ct64_cbcdec_keys *ctx,
const void *key, size_t len)
{
ctx->vtable = &br_aes_ct64_cbcdec_vtable;
ctx->num_rounds = br_aes_ct64_keysched(ctx->skey, key, len);
}
/* see bearssl_block.h */
void
br_aes_ct64_cbcdec_run(const br_aes_ct64_cbcdec_keys *ctx,
void *iv, void *data, size_t len)
{
unsigned char *buf;
uint64_t sk_exp[120];
uint32_t ivw[4];
br_aes_ct64_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);
br_range_dec32le(ivw, 4, iv);
buf = data;
while (len > 0) {
uint64_t q[8];
uint32_t w1[16], w2[16];
int i;
if (len >= 64) {
br_range_dec32le(w1, 16, buf);
} else {
br_range_dec32le(w1, len >> 2, buf);
}
for (i = 0; i < 4; i ++) {
br_aes_ct64_interleave_in(
&q[i], &q[i + 4], w1 + (i << 2));
}
br_aes_ct64_ortho(q);
br_aes_ct64_bitslice_decrypt(ctx->num_rounds, sk_exp, q);
br_aes_ct64_ortho(q);
for (i = 0; i < 4; i ++) {
br_aes_ct64_interleave_out(
w2 + (i << 2), q[i], q[i + 4]);
}
for (i = 0; i < 4; i ++) {
w2[i] ^= ivw[i];
}
if (len >= 64) {
for (i = 4; i < 16; i ++) {
w2[i] ^= w1[i - 4];
}
memcpy(ivw, w1 + 12, sizeof ivw);
br_range_enc32le(buf, w2, 16);
} else {
int j;
j = (int)(len >> 2);
for (i = 4; i < j; i ++) {
w2[i] ^= w1[i - 4];
}
memcpy(ivw, w1 + j - 4, sizeof ivw);
br_range_enc32le(buf, w2, j);
break;
}
buf += 64;
len -= 64;
}
br_range_enc32le(iv, ivw, 4);
}
/* see bearssl_block.h */
const br_block_cbcdec_class br_aes_ct64_cbcdec_vtable = {
sizeof(br_aes_ct64_cbcdec_keys),
16,
4,
(void (*)(const br_block_cbcdec_class **, const void *, size_t))
&br_aes_ct64_cbcdec_init,
(void (*)(const br_block_cbcdec_class *const *, void *, void *, size_t))
&br_aes_ct64_cbcdec_run
};
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