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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 | /* aes_decrypt.c - TinyCrypt implementation of AES decryption procedure */
/*
* Copyright (C) 2015 by Intel Corporation, All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Intel Corporation nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <tinycrypt/aes.h>
#include <tinycrypt/constants.h>
#include <tinycrypt/utils.h>
#define ZERO_BYTE 0x00
static const uint8_t inv_sbox[256] = {
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e,
0x81, 0xf3, 0xd7, 0xfb, 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87,
0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb, 0x54, 0x7b, 0x94, 0x32,
0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49,
0x6d, 0x8b, 0xd1, 0x25, 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16,
0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92, 0x6c, 0x70, 0x48, 0x50,
0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05,
0xb8, 0xb3, 0x45, 0x06, 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02,
0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b, 0x3a, 0x91, 0x11, 0x41,
0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8,
0x1c, 0x75, 0xdf, 0x6e, 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89,
0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b, 0xfc, 0x56, 0x3e, 0x4b,
0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59,
0x27, 0x80, 0xec, 0x5f, 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d,
0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef, 0xa0, 0xe0, 0x3b, 0x4d,
0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63,
0x55, 0x21, 0x0c, 0x7d
};
int32_t tc_aes128_set_decrypt_key(TCAesKeySched_t s, const uint8_t *k)
{
return tc_aes128_set_encrypt_key(s, k);
}
#define mult8(a)(_double_byte(_double_byte(_double_byte(a))))
#define mult9(a)(mult8(a)^(a))
#define multb(a)(mult8(a)^_double_byte(a)^(a))
#define multd(a)(mult8(a)^_double_byte(_double_byte(a))^(a))
#define multe(a)(mult8(a)^_double_byte(_double_byte(a))^_double_byte(a))
static inline void mult_row_column(uint8_t *out, const uint8_t *in)
{
out[0] = multe(in[0]) ^ multb(in[1]) ^ multd(in[2]) ^ mult9(in[3]);
out[1] = mult9(in[0]) ^ multe(in[1]) ^ multb(in[2]) ^ multd(in[3]);
out[2] = multd(in[0]) ^ mult9(in[1]) ^ multe(in[2]) ^ multb(in[3]);
out[3] = multb(in[0]) ^ multd(in[1]) ^ mult9(in[2]) ^ multe(in[3]);
}
static inline void inv_mix_columns(uint8_t *s)
{
uint8_t t[Nb*Nk];
mult_row_column(t, s);
mult_row_column(&t[Nb], s+Nb);
mult_row_column(&t[2*Nb], s+(2*Nb));
mult_row_column(&t[3*Nb], s+(3*Nb));
(void)_copy(s, sizeof(t), t, sizeof(t));
}
static inline void add_round_key(uint8_t *s, const uint32_t *k)
{
s[0] ^= (uint8_t)(k[0] >> 24); s[1] ^= (uint8_t)(k[0] >> 16);
s[2] ^= (uint8_t)(k[0] >> 8); s[3] ^= (uint8_t)(k[0]);
s[4] ^= (uint8_t)(k[1] >> 24); s[5] ^= (uint8_t)(k[1] >> 16);
s[6] ^= (uint8_t)(k[1] >> 8); s[7] ^= (uint8_t)(k[1]);
s[8] ^= (uint8_t)(k[2] >> 24); s[9] ^= (uint8_t)(k[2] >> 16);
s[10] ^= (uint8_t)(k[2] >> 8); s[11] ^= (uint8_t)(k[2]);
s[12] ^= (uint8_t)(k[3] >> 24); s[13] ^= (uint8_t)(k[3] >> 16);
s[14] ^= (uint8_t)(k[3] >> 8); s[15] ^= (uint8_t)(k[3]);
}
static inline void inv_sub_bytes(uint8_t *s)
{
uint32_t i;
for (i = 0; i < (Nb*Nk); ++i) {
s[i] = inv_sbox[s[i]];
}
}
/*
* This inv_shift_rows also implements the matrix flip required for
* inv_mix_columns, but performs it here to reduce the number of memory
* operations.
*/
static inline void inv_shift_rows(uint8_t *s)
{
uint8_t t[Nb*Nk];
t[0] = s[0]; t[1] = s[13]; t[2] = s[10]; t[3] = s[7];
t[4] = s[4]; t[5] = s[1]; t[6] = s[14]; t[7] = s[11];
t[8] = s[8]; t[9] = s[5]; t[10] = s[2]; t[11] = s[15];
t[12] = s[12]; t[13] = s[9]; t[14] = s[6]; t[15] = s[3];
(void)_copy(s, sizeof(t), t, sizeof(t));
}
int32_t tc_aes_decrypt(uint8_t *out, const uint8_t *in, const TCAesKeySched_t s)
{
uint8_t state[Nk*Nb];
uint32_t i;
if (out == (uint8_t *) 0) {
return TC_CRYPTO_FAIL;
} else if (in == (const uint8_t *) 0) {
return TC_CRYPTO_FAIL;
} else if (s == (TCAesKeySched_t) 0) {
return TC_CRYPTO_FAIL;
}
(void)_copy(state, sizeof(state), in, sizeof(state));
add_round_key(state, s->words + Nb*Nr);
for (i = Nr-1; i > 0; --i) {
inv_shift_rows(state);
inv_sub_bytes(state);
add_round_key(state, s->words + Nb*i);
inv_mix_columns(state);
}
inv_shift_rows(state);
inv_sub_bytes(state);
add_round_key(state, s->words);
(void)_copy(out, sizeof(state), state, sizeof(state));
/*zeroing out one byte state buffer */
_set(state, ZERO_BYTE, sizeof(state));
return TC_CRYPTO_SUCCESS;
}
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