117 lines
3.0 KiB
C
117 lines
3.0 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 "t_inner.h"
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/* see bearssl_block.h */
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void
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br_aes_ct_ctr_init(br_aes_ct_ctr_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_ctr_vtable;
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ctx->num_rounds = br_aes_ct_keysched(ctx->skey, key, len);
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}
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static void
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xorbuf(void *dst, const void *src, size_t len)
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{
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unsigned char *d;
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const unsigned char *s;
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d = dst;
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s = src;
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while (len -- > 0) {
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*d ++ ^= *s ++;
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}
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}
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/* see bearssl_block.h */
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uint32_t
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br_aes_ct_ctr_run(const br_aes_ct_ctr_keys *ctx,
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const void *iv, uint32_t cc, void *data, size_t len)
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{
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unsigned char *buf;
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const unsigned char *ivbuf;
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uint32_t iv0, iv1, iv2;
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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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buf = data;
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while (len > 0) {
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uint32_t q[8];
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unsigned char tmp[32];
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/*
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* TODO: see if we can save on the first br_aes_ct_ortho()
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* call, since iv0/iv1/iv2 are constant for the whole run.
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*/
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q[0] = q[1] = iv0;
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q[2] = q[3] = iv1;
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q[4] = q[5] = iv2;
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q[6] = br_swap32(cc);
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q[7] = br_swap32(cc + 1);
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br_aes_ct_ortho(q);
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br_aes_ct_bitslice_encrypt(ctx->num_rounds, sk_exp, q);
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br_aes_ct_ortho(q);
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br_enc32le(tmp, q[0]);
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br_enc32le(tmp + 4, q[2]);
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br_enc32le(tmp + 8, q[4]);
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br_enc32le(tmp + 12, q[6]);
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br_enc32le(tmp + 16, q[1]);
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br_enc32le(tmp + 20, q[3]);
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br_enc32le(tmp + 24, q[5]);
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br_enc32le(tmp + 28, q[7]);
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if (len <= 32) {
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xorbuf(buf, tmp, len);
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cc ++;
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if (len > 16) {
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cc ++;
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}
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break;
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}
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xorbuf(buf, tmp, 32);
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buf += 32;
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len -= 32;
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cc += 2;
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}
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return cc;
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}
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/* see bearssl_block.h */
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const br_block_ctr_class br_aes_ct_ctr_vtable PROGMEM = {
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sizeof(br_aes_ct_ctr_keys),
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16,
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4,
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(void (*)(const br_block_ctr_class **, const void *, size_t))
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&br_aes_ct_ctr_init,
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(uint32_t (*)(const br_block_ctr_class *const *,
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const void *, uint32_t, void *, size_t))
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&br_aes_ct_ctr_run
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};
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