1 /* aes_encrypt.c - TinyCrypt implementation of AES encryption procedure */
2
3 /*
4 * Copyright (C) 2017 by Intel Corporation, All Rights Reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * - Redistributions of source code must retain the above copyright notice,
10 * this list of conditions and the following disclaimer.
11 *
12 * - Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * - Neither the name of Intel Corporation nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #include <tinycrypt/aes.h>
34 #include <tinycrypt/utils.h>
35 #include <tinycrypt/constants.h>
36
37 static const uint8_t sbox[256] = {
38 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b,
39 0xfe, 0xd7, 0xab, 0x76, 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0,
40 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, 0xb7, 0xfd, 0x93, 0x26,
41 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
42 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2,
43 0xeb, 0x27, 0xb2, 0x75, 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0,
44 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, 0x53, 0xd1, 0x00, 0xed,
45 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
46 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f,
47 0x50, 0x3c, 0x9f, 0xa8, 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5,
48 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, 0xcd, 0x0c, 0x13, 0xec,
49 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
50 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14,
51 0xde, 0x5e, 0x0b, 0xdb, 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c,
52 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, 0xe7, 0xc8, 0x37, 0x6d,
53 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
54 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f,
55 0x4b, 0xbd, 0x8b, 0x8a, 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e,
56 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, 0xe1, 0xf8, 0x98, 0x11,
57 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
58 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f,
59 0xb0, 0x54, 0xbb, 0x16
60 };
61
rotword(unsigned int a)62 static inline unsigned int rotword(unsigned int a)
63 {
64 return (((a) >> 24) | ((a) << 8));
65 }
66
67 #define subbyte(a, o)(sbox[((a) >> (o))&0xff] << (o))
68 #define subword(a)(subbyte(a, 24)|subbyte(a, 16)|subbyte(a, 8)|subbyte(a, 0))
69
tc_aes128_set_encrypt_key(TCAesKeySched_t s,const uint8_t * k)70 int tc_aes128_set_encrypt_key(TCAesKeySched_t s, const uint8_t *k)
71 {
72 const unsigned int rconst[11] = {
73 0x00000000, 0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000,
74 0x20000000, 0x40000000, 0x80000000, 0x1b000000, 0x36000000
75 };
76 unsigned int i;
77 unsigned int t;
78
79 if (s == (TCAesKeySched_t) 0) {
80 return TC_CRYPTO_FAIL;
81 } else if (k == (const uint8_t *) 0) {
82 return TC_CRYPTO_FAIL;
83 }
84
85 for (i = 0; i < Nk; ++i) {
86 s->words[i] = (k[Nb * i] << 24) | (k[Nb * i + 1] << 16) |
87 (k[Nb * i + 2] << 8) | (k[Nb * i + 3]);
88 }
89
90 for (; i < (Nb * (Nr + 1)); ++i) {
91 t = s->words[i - 1];
92 if ((i % Nk) == 0) {
93 t = subword(rotword(t)) ^ rconst[i / Nk];
94 }
95 s->words[i] = s->words[i - Nk] ^ t;
96 }
97
98 return TC_CRYPTO_SUCCESS;
99 }
100
add_round_key(uint8_t * s,const unsigned int * k)101 static inline void add_round_key(uint8_t *s, const unsigned int *k)
102 {
103 s[0] ^= (uint8_t)(k[0] >> 24); s[1] ^= (uint8_t)(k[0] >> 16);
104 s[2] ^= (uint8_t)(k[0] >> 8); s[3] ^= (uint8_t)(k[0]);
105 s[4] ^= (uint8_t)(k[1] >> 24); s[5] ^= (uint8_t)(k[1] >> 16);
106 s[6] ^= (uint8_t)(k[1] >> 8); s[7] ^= (uint8_t)(k[1]);
107 s[8] ^= (uint8_t)(k[2] >> 24); s[9] ^= (uint8_t)(k[2] >> 16);
108 s[10] ^= (uint8_t)(k[2] >> 8); s[11] ^= (uint8_t)(k[2]);
109 s[12] ^= (uint8_t)(k[3] >> 24); s[13] ^= (uint8_t)(k[3] >> 16);
110 s[14] ^= (uint8_t)(k[3] >> 8); s[15] ^= (uint8_t)(k[3]);
111 }
112
sub_bytes(uint8_t * s)113 static inline void sub_bytes(uint8_t *s)
114 {
115 unsigned int i;
116
117 for (i = 0; i < (Nb * Nk); ++i) {
118 s[i] = sbox[s[i]];
119 }
120 }
121
122 #define triple(a)(_double_byte(a)^(a))
123
mult_row_column(uint8_t * out,const uint8_t * in)124 static inline void mult_row_column(uint8_t *out, const uint8_t *in)
125 {
126 out[0] = _double_byte(in[0]) ^ triple(in[1]) ^ in[2] ^ in[3];
127 out[1] = in[0] ^ _double_byte(in[1]) ^ triple(in[2]) ^ in[3];
128 out[2] = in[0] ^ in[1] ^ _double_byte(in[2]) ^ triple(in[3]);
129 out[3] = triple(in[0]) ^ in[1] ^ in[2] ^ _double_byte(in[3]);
130 }
131
mix_columns(uint8_t * s)132 static inline void mix_columns(uint8_t *s)
133 {
134 uint8_t t[Nb * Nk];
135
136 mult_row_column(t, s);
137 mult_row_column(&t[Nb], s + Nb);
138 mult_row_column(&t[2 * Nb], s + (2 * Nb));
139 mult_row_column(&t[3 * Nb], s + (3 * Nb));
140 (void) _copy(s, sizeof(t), t, sizeof(t));
141 }
142
143 /*
144 * This shift_rows also implements the matrix flip required for mix_columns, but
145 * performs it here to reduce the number of memory operations.
146 */
shift_rows(uint8_t * s)147 static inline void shift_rows(uint8_t *s)
148 {
149 uint8_t t[Nb * Nk];
150
151 t[0] = s[0]; t[1] = s[5]; t[2] = s[10]; t[3] = s[15];
152 t[4] = s[4]; t[5] = s[9]; t[6] = s[14]; t[7] = s[3];
153 t[8] = s[8]; t[9] = s[13]; t[10] = s[2]; t[11] = s[7];
154 t[12] = s[12]; t[13] = s[1]; t[14] = s[6]; t[15] = s[11];
155 (void) _copy(s, sizeof(t), t, sizeof(t));
156 }
157
tc_aes_encrypt(uint8_t * out,const uint8_t * in,const TCAesKeySched_t s)158 int tc_aes_encrypt(uint8_t *out, const uint8_t *in, const TCAesKeySched_t s)
159 {
160 uint8_t state[Nk * Nb];
161 unsigned int i;
162
163 if (out == (uint8_t *) 0) {
164 return TC_CRYPTO_FAIL;
165 } else if (in == (const uint8_t *) 0) {
166 return TC_CRYPTO_FAIL;
167 } else if (s == (TCAesKeySched_t) 0) {
168 return TC_CRYPTO_FAIL;
169 }
170
171 (void)_copy(state, sizeof(state), in, sizeof(state));
172 add_round_key(state, s->words);
173
174 for (i = 0; i < (Nr - 1); ++i) {
175 sub_bytes(state);
176 shift_rows(state);
177 mix_columns(state);
178 add_round_key(state, s->words + Nb * (i + 1));
179 }
180
181 sub_bytes(state);
182 shift_rows(state);
183 add_round_key(state, s->words + Nb * (i + 1));
184
185 (void)_copy(out, sizeof(state), state, sizeof(state));
186
187 /* zeroing out the state buffer */
188 _set(state, TC_ZERO_BYTE, sizeof(state));
189
190 return TC_CRYPTO_SUCCESS;
191 }
192
