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_ctr_init(br_aes_ct_ctr_keys *ctx, 30 const void *key, size_t len) 31 { 32 ctx->vtable = &br_aes_ct_ctr_vtable; 33 ctx->num_rounds = br_aes_ct_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_ct_ctr_run(const br_aes_ct_ctr_keys *ctx, 52 const void *iv, uint32_t cc, void *data, size_t len) 53 { 54 unsigned char *buf; 55 const unsigned char *ivbuf; 56 uint32_t iv0, iv1, iv2; 57 uint32_t sk_exp[120]; 58 59 br_aes_ct_skey_expand(sk_exp, ctx->num_rounds, ctx->skey); 60 ivbuf = iv; 61 iv0 = br_dec32le(ivbuf); 62 iv1 = br_dec32le(ivbuf + 4); 63 iv2 = br_dec32le(ivbuf + 8); 64 buf = data; 65 while (len > 0) { 66 uint32_t q[8]; 67 unsigned char tmp[32]; 68 69 /* 70 * TODO: see if we can save on the first br_aes_ct_ortho() 71 * call, since iv0/iv1/iv2 are constant for the whole run. 72 */ 73 q[0] = q[1] = iv0; 74 q[2] = q[3] = iv1; 75 q[4] = q[5] = iv2; 76 q[6] = br_swap32(cc); 77 q[7] = br_swap32(cc + 1); 78 br_aes_ct_ortho(q); 79 br_aes_ct_bitslice_encrypt(ctx->num_rounds, sk_exp, q); 80 br_aes_ct_ortho(q); 81 br_enc32le(tmp, q[0]); 82 br_enc32le(tmp + 4, q[2]); 83 br_enc32le(tmp + 8, q[4]); 84 br_enc32le(tmp + 12, q[6]); 85 br_enc32le(tmp + 16, q[1]); 86 br_enc32le(tmp + 20, q[3]); 87 br_enc32le(tmp + 24, q[5]); 88 br_enc32le(tmp + 28, q[7]); 89 90 if (len <= 32) { 91 xorbuf(buf, tmp, len); 92 cc ++; 93 if (len > 16) { 94 cc ++; 95 } 96 break; 97 } 98 xorbuf(buf, tmp, 32); 99 buf += 32; 100 len -= 32; 101 cc += 2; 102 } 103 return cc; 104 } 105 106 /* see bearssl_block.h */ 107 const br_block_ctr_class br_aes_ct_ctr_vtable = { 108 sizeof(br_aes_ct_ctr_keys), 109 16, 110 4, 111 (void (*)(const br_block_ctr_class **, const void *, size_t)) 112 &br_aes_ct_ctr_init, 113 (uint32_t (*)(const br_block_ctr_class *const *, 114 const void *, uint32_t, void *, size_t)) 115 &br_aes_ct_ctr_run 116 }; 117