1 /* 2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org> 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining 5 * a copy of this software and associated documentation files (the 6 * "Software"), to deal in the Software without restriction, including 7 * without limitation the rights to use, copy, modify, merge, publish, 8 * distribute, sublicense, and/or sell copies of the Software, and to 9 * permit persons to whom the Software is furnished to do so, subject to 10 * the following conditions: 11 * 12 * The above copyright notice and this permission notice shall be 13 * included in all copies or substantial portions of the Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 * SOFTWARE. 23 */ 24 25 #include "inner.h" 26 27 /* see bearssl_block.h */ 28 void 29 br_aes_small_ctr_init(br_aes_small_ctr_keys *ctx, 30 const void *key, size_t len) 31 { 32 ctx->vtable = &br_aes_small_ctr_vtable; 33 ctx->num_rounds = br_aes_keysched(ctx->skey, key, len); 34 } 35 36 static void 37 xorbuf(void *dst, const void *src, size_t len) 38 { 39 unsigned char *d; 40 const unsigned char *s; 41 42 d = dst; 43 s = src; 44 while (len -- > 0) { 45 *d ++ ^= *s ++; 46 } 47 } 48 49 /* see bearssl_block.h */ 50 uint32_t 51 br_aes_small_ctr_run(const br_aes_small_ctr_keys *ctx, 52 const void *iv, uint32_t cc, void *data, size_t len) 53 { 54 unsigned char *buf; 55 56 buf = data; 57 while (len > 0) { 58 unsigned char tmp[16]; 59 60 memcpy(tmp, iv, 12); 61 br_enc32be(tmp + 12, cc ++); 62 br_aes_small_encrypt(ctx->num_rounds, ctx->skey, tmp); 63 if (len <= 16) { 64 xorbuf(buf, tmp, len); 65 break; 66 } 67 xorbuf(buf, tmp, 16); 68 buf += 16; 69 len -= 16; 70 } 71 return cc; 72 } 73 74 /* see bearssl_block.h */ 75 const br_block_ctr_class br_aes_small_ctr_vtable = { 76 sizeof(br_aes_small_ctr_keys), 77 16, 78 4, 79 (void (*)(const br_block_ctr_class **, const void *, size_t)) 80 &br_aes_small_ctr_init, 81 (uint32_t (*)(const br_block_ctr_class *const *, 82 const void *, uint32_t, void *, size_t)) 83 &br_aes_small_ctr_run 84 }; 85