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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_ct_cbcdec_init(br_aes_ct_cbcdec_keys *ctx,
const void *key, size_t len)
{
ctx->vtable = &br_aes_ct_cbcdec_vtable;
ctx->num_rounds = br_aes_ct_keysched(ctx->skey, key, len);
}
/* see bearssl_block.h */
void
br_aes_ct_cbcdec_run(const br_aes_ct_cbcdec_keys *ctx,
void *iv, void *data, size_t len)
{
unsigned char *buf, *ivbuf;
uint32_t iv0, iv1, iv2, iv3;
uint32_t sk_exp[120];
br_aes_ct_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);
ivbuf = iv;
iv0 = br_dec32le(ivbuf);
iv1 = br_dec32le(ivbuf + 4);
iv2 = br_dec32le(ivbuf + 8);
iv3 = br_dec32le(ivbuf + 12);
buf = data;
while (len > 0) {
uint32_t q[8], sq[8];
q[0] = br_dec32le(buf);
q[2] = br_dec32le(buf + 4);
q[4] = br_dec32le(buf + 8);
q[6] = br_dec32le(buf + 12);
if (len >= 32) {
q[1] = br_dec32le(buf + 16);
q[3] = br_dec32le(buf + 20);
q[5] = br_dec32le(buf + 24);
q[7] = br_dec32le(buf + 28);
} else {
q[1] = 0;
q[3] = 0;
q[5] = 0;
q[7] = 0;
}
memcpy(sq, q, sizeof q);
br_aes_ct_ortho(q);
br_aes_ct_bitslice_decrypt(ctx->num_rounds, sk_exp, q);
br_aes_ct_ortho(q);
br_enc32le(buf, q[0] ^ iv0);
br_enc32le(buf + 4, q[2] ^ iv1);
br_enc32le(buf + 8, q[4] ^ iv2);
br_enc32le(buf + 12, q[6] ^ iv3);
if (len < 32) {
iv0 = sq[0];
iv1 = sq[2];
iv2 = sq[4];
iv3 = sq[6];
break;
}
br_enc32le(buf + 16, q[1] ^ sq[0]);
br_enc32le(buf + 20, q[3] ^ sq[2]);
br_enc32le(buf + 24, q[5] ^ sq[4]);
br_enc32le(buf + 28, q[7] ^ sq[6]);
iv0 = sq[1];
iv1 = sq[3];
iv2 = sq[5];
iv3 = sq[7];
buf += 32;
len -= 32;
}
br_enc32le(ivbuf, iv0);
br_enc32le(ivbuf + 4, iv1);
br_enc32le(ivbuf + 8, iv2);
br_enc32le(ivbuf + 12, iv3);
}
/* see bearssl_block.h */
const br_block_cbcdec_class br_aes_ct_cbcdec_vtable = {
sizeof(br_aes_ct_cbcdec_keys),
16,
4,
(void (*)(const br_block_cbcdec_class **, const void *, size_t))
&br_aes_ct_cbcdec_init,
(void (*)(const br_block_cbcdec_class *const *, void *, void *, size_t))
&br_aes_ct_cbcdec_run
};
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