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_ct_cbcdec_init(br_aes_ct_cbcdec_keys *ctx, 30 const void *key, size_t len) 31 { 32 ctx->vtable = &br_aes_ct_cbcdec_vtable; 33 ctx->num_rounds = br_aes_ct_keysched(ctx->skey, key, len); 34 } 35 36 /* see bearssl_block.h */ 37 void 38 br_aes_ct_cbcdec_run(const br_aes_ct_cbcdec_keys *ctx, 39 void *iv, void *data, size_t len) 40 { 41 unsigned char *buf, *ivbuf; 42 uint32_t iv0, iv1, iv2, iv3; 43 uint32_t sk_exp[120]; 44 45 br_aes_ct_skey_expand(sk_exp, ctx->num_rounds, ctx->skey); 46 ivbuf = iv; 47 iv0 = br_dec32le(ivbuf); 48 iv1 = br_dec32le(ivbuf + 4); 49 iv2 = br_dec32le(ivbuf + 8); 50 iv3 = br_dec32le(ivbuf + 12); 51 buf = data; 52 while (len > 0) { 53 uint32_t q[8], sq[8]; 54 55 q[0] = br_dec32le(buf); 56 q[2] = br_dec32le(buf + 4); 57 q[4] = br_dec32le(buf + 8); 58 q[6] = br_dec32le(buf + 12); 59 if (len >= 32) { 60 q[1] = br_dec32le(buf + 16); 61 q[3] = br_dec32le(buf + 20); 62 q[5] = br_dec32le(buf + 24); 63 q[7] = br_dec32le(buf + 28); 64 } else { 65 q[1] = 0; 66 q[3] = 0; 67 q[5] = 0; 68 q[7] = 0; 69 } 70 memcpy(sq, q, sizeof q); 71 br_aes_ct_ortho(q); 72 br_aes_ct_bitslice_decrypt(ctx->num_rounds, sk_exp, q); 73 br_aes_ct_ortho(q); 74 br_enc32le(buf, q[0] ^ iv0); 75 br_enc32le(buf + 4, q[2] ^ iv1); 76 br_enc32le(buf + 8, q[4] ^ iv2); 77 br_enc32le(buf + 12, q[6] ^ iv3); 78 if (len < 32) { 79 iv0 = sq[0]; 80 iv1 = sq[2]; 81 iv2 = sq[4]; 82 iv3 = sq[6]; 83 break; 84 } 85 br_enc32le(buf + 16, q[1] ^ sq[0]); 86 br_enc32le(buf + 20, q[3] ^ sq[2]); 87 br_enc32le(buf + 24, q[5] ^ sq[4]); 88 br_enc32le(buf + 28, q[7] ^ sq[6]); 89 iv0 = sq[1]; 90 iv1 = sq[3]; 91 iv2 = sq[5]; 92 iv3 = sq[7]; 93 buf += 32; 94 len -= 32; 95 } 96 br_enc32le(ivbuf, iv0); 97 br_enc32le(ivbuf + 4, iv1); 98 br_enc32le(ivbuf + 8, iv2); 99 br_enc32le(ivbuf + 12, iv3); 100 } 101 102 /* see bearssl_block.h */ 103 const br_block_cbcdec_class br_aes_ct_cbcdec_vtable = { 104 sizeof(br_aes_ct_cbcdec_keys), 105 16, 106 4, 107 (void (*)(const br_block_cbcdec_class **, const void *, size_t)) 108 &br_aes_ct_cbcdec_init, 109 (void (*)(const br_block_cbcdec_class *const *, void *, void *, size_t)) 110 &br_aes_ct_cbcdec_run 111 }; 112