112 lines
3.1 KiB
C
112 lines
3.1 KiB
C
/*
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* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include "inner.h"
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/* see bearssl_block.h */
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void
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br_aes_ct_cbcdec_init(br_aes_ct_cbcdec_keys *ctx,
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const void *key, size_t len)
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{
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ctx->vtable = &br_aes_ct_cbcdec_vtable;
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ctx->num_rounds = br_aes_ct_keysched(ctx->skey, key, len);
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}
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/* see bearssl_block.h */
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void
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br_aes_ct_cbcdec_run(const br_aes_ct_cbcdec_keys *ctx,
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void *iv, void *data, size_t len)
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{
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unsigned char *buf, *ivbuf;
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uint32_t iv0, iv1, iv2, iv3;
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uint32_t sk_exp[120];
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br_aes_ct_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);
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ivbuf = iv;
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iv0 = br_dec32le(ivbuf);
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iv1 = br_dec32le(ivbuf + 4);
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iv2 = br_dec32le(ivbuf + 8);
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iv3 = br_dec32le(ivbuf + 12);
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buf = data;
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while (len > 0) {
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uint32_t q[8], sq[8];
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q[0] = br_dec32le(buf);
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q[2] = br_dec32le(buf + 4);
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q[4] = br_dec32le(buf + 8);
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q[6] = br_dec32le(buf + 12);
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if (len >= 32) {
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q[1] = br_dec32le(buf + 16);
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q[3] = br_dec32le(buf + 20);
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q[5] = br_dec32le(buf + 24);
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q[7] = br_dec32le(buf + 28);
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} else {
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q[1] = 0;
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q[3] = 0;
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q[5] = 0;
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q[7] = 0;
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}
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memcpy(sq, q, sizeof q);
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br_aes_ct_ortho(q);
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br_aes_ct_bitslice_decrypt(ctx->num_rounds, sk_exp, q);
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br_aes_ct_ortho(q);
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br_enc32le(buf, q[0] ^ iv0);
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br_enc32le(buf + 4, q[2] ^ iv1);
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br_enc32le(buf + 8, q[4] ^ iv2);
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br_enc32le(buf + 12, q[6] ^ iv3);
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if (len < 32) {
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iv0 = sq[0];
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iv1 = sq[2];
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iv2 = sq[4];
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iv3 = sq[6];
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break;
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}
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br_enc32le(buf + 16, q[1] ^ sq[0]);
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br_enc32le(buf + 20, q[3] ^ sq[2]);
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br_enc32le(buf + 24, q[5] ^ sq[4]);
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br_enc32le(buf + 28, q[7] ^ sq[6]);
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iv0 = sq[1];
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iv1 = sq[3];
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iv2 = sq[5];
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iv3 = sq[7];
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buf += 32;
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len -= 32;
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}
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br_enc32le(ivbuf, iv0);
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br_enc32le(ivbuf + 4, iv1);
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br_enc32le(ivbuf + 8, iv2);
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br_enc32le(ivbuf + 12, iv3);
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}
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/* see bearssl_block.h */
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const br_block_cbcdec_class br_aes_ct_cbcdec_vtable = {
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sizeof(br_aes_ct_cbcdec_keys),
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16,
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4,
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(void (*)(const br_block_cbcdec_class **, const void *, size_t))
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&br_aes_ct_cbcdec_init,
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(void (*)(const br_block_cbcdec_class *const *, void *, void *, size_t))
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&br_aes_ct_cbcdec_run
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};
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