_ Git - BearSSL/blob - src/symcipher/aes_ct_enc.c

   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 static inline void
  28 add_round_key(uint32_t *q, const uint32_t *sk)
  29 {
  30         q[0] ^= sk[0];
  31         q[1] ^= sk[1];
  32         q[2] ^= sk[2];
  33         q[3] ^= sk[3];
  34         q[4] ^= sk[4];
  35         q[5] ^= sk[5];
  36         q[6] ^= sk[6];
  37         q[7] ^= sk[7];
  38 }
  39
  40 static inline void
  41 shift_rows(uint32_t *q)
  42 {
  43         int i;
  44
  45         for (i = 0; i < 8; i ++) {
  46                 uint32_t x;
  47
  48                 x = q[i];
  49                 q[i] = (x & 0x000000FF)
  50                         | ((x & 0x0000FC00) >> 2) | ((x & 0x00000300) << 6)
  51                         | ((x & 0x00F00000) >> 4) | ((x & 0x000F0000) << 4)
  52                         | ((x & 0xC0000000) >> 6) | ((x & 0x3F000000) << 2);
  53         }
  54 }
  55
  56 static inline uint32_t
  57 rotr16(uint32_t x)
  58 {
  59         return (x << 16) | (x >> 16);
  60 }
  61
  62 static inline void
  63 mix_columns(uint32_t *q)
  64 {
  65         uint32_t q0, q1, q2, q3, q4, q5, q6, q7;
  66         uint32_t r0, r1, r2, r3, r4, r5, r6, r7;
  67
  68         q0 = q[0];
  69         q1 = q[1];
  70         q2 = q[2];
  71         q3 = q[3];
  72         q4 = q[4];
  73         q5 = q[5];
  74         q6 = q[6];
  75         q7 = q[7];
  76         r0 = (q0 >> 8) | (q0 << 24);
  77         r1 = (q1 >> 8) | (q1 << 24);
  78         r2 = (q2 >> 8) | (q2 << 24);
  79         r3 = (q3 >> 8) | (q3 << 24);
  80         r4 = (q4 >> 8) | (q4 << 24);
  81         r5 = (q5 >> 8) | (q5 << 24);
  82         r6 = (q6 >> 8) | (q6 << 24);
  83         r7 = (q7 >> 8) | (q7 << 24);
  84
  85         q[0] = q7 ^ r7 ^ r0 ^ rotr16(q0 ^ r0);
  86         q[1] = q0 ^ r0 ^ q7 ^ r7 ^ r1 ^ rotr16(q1 ^ r1);
  87         q[2] = q1 ^ r1 ^ r2 ^ rotr16(q2 ^ r2);
  88         q[3] = q2 ^ r2 ^ q7 ^ r7 ^ r3 ^ rotr16(q3 ^ r3);
  89         q[4] = q3 ^ r3 ^ q7 ^ r7 ^ r4 ^ rotr16(q4 ^ r4);
  90         q[5] = q4 ^ r4 ^ r5 ^ rotr16(q5 ^ r5);
  91         q[6] = q5 ^ r5 ^ r6 ^ rotr16(q6 ^ r6);
  92         q[7] = q6 ^ r6 ^ r7 ^ rotr16(q7 ^ r7);
  93 }
  94
  95 /* see inner.h */
  96 void
  97 br_aes_ct_bitslice_encrypt(unsigned num_rounds,
  98         const uint32_t *skey, uint32_t *q)
  99 {
 100         unsigned u;
 101
 102         add_round_key(q, skey);
 103         for (u = 1; u < num_rounds; u ++) {
 104                 br_aes_ct_bitslice_Sbox(q);
 105                 shift_rows(q);
 106                 mix_columns(q);
 107                 add_round_key(q, skey + (u << 3));
 108         }
 109         br_aes_ct_bitslice_Sbox(q);
 110         shift_rows(q);
 111         add_round_key(q, skey + (num_rounds << 3));
 112 }