1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2017-2019 Linaro Ltd <ard.biesheuvel@linaro.org> 4 */ 5 6 #include <crypto/aes.h> 7 #include <linux/crypto.h> 8 #include <linux/export.h> 9 #include <linux/module.h> 10 #include <linux/unaligned.h> 11 12 /* 13 * Emit the sbox as volatile const to prevent the compiler from doing 14 * constant folding on sbox references involving fixed indexes. 15 */ 16 static volatile const u8 __cacheline_aligned aes_sbox[] = { 17 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 18 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, 19 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 20 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, 21 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 22 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, 23 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 24 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, 25 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 26 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, 27 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 28 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, 29 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 30 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, 31 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 32 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, 33 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 34 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, 35 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 36 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, 37 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 38 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, 39 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 40 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, 41 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 42 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, 43 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 44 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, 45 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 46 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, 47 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 48 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16, 49 }; 50 51 static volatile const u8 __cacheline_aligned aes_inv_sbox[] = { 52 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 53 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb, 54 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 55 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb, 56 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 57 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e, 58 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 59 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25, 60 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 61 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92, 62 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 63 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84, 64 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 65 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06, 66 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 67 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b, 68 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 69 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73, 70 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 71 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e, 72 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 73 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b, 74 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 75 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4, 76 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 77 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f, 78 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 79 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef, 80 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 81 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61, 82 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 83 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d, 84 }; 85 86 extern const u8 crypto_aes_sbox[256] __alias(aes_sbox); 87 extern const u8 crypto_aes_inv_sbox[256] __alias(aes_inv_sbox); 88 89 EXPORT_SYMBOL(crypto_aes_sbox); 90 EXPORT_SYMBOL(crypto_aes_inv_sbox); 91 92 static u32 mul_by_x(u32 w) 93 { 94 u32 x = w & 0x7f7f7f7f; 95 u32 y = w & 0x80808080; 96 97 /* multiply by polynomial 'x' (0b10) in GF(2^8) */ 98 return (x << 1) ^ (y >> 7) * 0x1b; 99 } 100 101 static u32 mul_by_x2(u32 w) 102 { 103 u32 x = w & 0x3f3f3f3f; 104 u32 y = w & 0x80808080; 105 u32 z = w & 0x40404040; 106 107 /* multiply by polynomial 'x^2' (0b100) in GF(2^8) */ 108 return (x << 2) ^ (y >> 7) * 0x36 ^ (z >> 6) * 0x1b; 109 } 110 111 static u32 mix_columns(u32 x) 112 { 113 /* 114 * Perform the following matrix multiplication in GF(2^8) 115 * 116 * | 0x2 0x3 0x1 0x1 | | x[0] | 117 * | 0x1 0x2 0x3 0x1 | | x[1] | 118 * | 0x1 0x1 0x2 0x3 | x | x[2] | 119 * | 0x3 0x1 0x1 0x2 | | x[3] | 120 */ 121 u32 y = mul_by_x(x) ^ ror32(x, 16); 122 123 return y ^ ror32(x ^ y, 8); 124 } 125 126 static u32 inv_mix_columns(u32 x) 127 { 128 /* 129 * Perform the following matrix multiplication in GF(2^8) 130 * 131 * | 0xe 0xb 0xd 0x9 | | x[0] | 132 * | 0x9 0xe 0xb 0xd | | x[1] | 133 * | 0xd 0x9 0xe 0xb | x | x[2] | 134 * | 0xb 0xd 0x9 0xe | | x[3] | 135 * 136 * which can conveniently be reduced to 137 * 138 * | 0x2 0x3 0x1 0x1 | | 0x5 0x0 0x4 0x0 | | x[0] | 139 * | 0x1 0x2 0x3 0x1 | | 0x0 0x5 0x0 0x4 | | x[1] | 140 * | 0x1 0x1 0x2 0x3 | x | 0x4 0x0 0x5 0x0 | x | x[2] | 141 * | 0x3 0x1 0x1 0x2 | | 0x0 0x4 0x0 0x5 | | x[3] | 142 */ 143 u32 y = mul_by_x2(x); 144 145 return mix_columns(x ^ y ^ ror32(y, 16)); 146 } 147 148 static __always_inline u32 subshift(u32 in[], int pos) 149 { 150 return (aes_sbox[in[pos] & 0xff]) ^ 151 (aes_sbox[(in[(pos + 1) % 4] >> 8) & 0xff] << 8) ^ 152 (aes_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^ 153 (aes_sbox[(in[(pos + 3) % 4] >> 24) & 0xff] << 24); 154 } 155 156 static __always_inline u32 inv_subshift(u32 in[], int pos) 157 { 158 return (aes_inv_sbox[in[pos] & 0xff]) ^ 159 (aes_inv_sbox[(in[(pos + 3) % 4] >> 8) & 0xff] << 8) ^ 160 (aes_inv_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^ 161 (aes_inv_sbox[(in[(pos + 1) % 4] >> 24) & 0xff] << 24); 162 } 163 164 static u32 subw(u32 in) 165 { 166 return (aes_sbox[in & 0xff]) ^ 167 (aes_sbox[(in >> 8) & 0xff] << 8) ^ 168 (aes_sbox[(in >> 16) & 0xff] << 16) ^ 169 (aes_sbox[(in >> 24) & 0xff] << 24); 170 } 171 172 /** 173 * aes_expandkey - Expands the AES key as described in FIPS-197 174 * @ctx: The location where the computed key will be stored. 175 * @in_key: The supplied key. 176 * @key_len: The length of the supplied key. 177 * 178 * Returns 0 on success. The function fails only if an invalid key size (or 179 * pointer) is supplied. 180 * The expanded key size is 240 bytes (max of 14 rounds with a unique 16 bytes 181 * key schedule plus a 16 bytes key which is used before the first round). 182 * The decryption key is prepared for the "Equivalent Inverse Cipher" as 183 * described in FIPS-197. The first slot (16 bytes) of each key (enc or dec) is 184 * for the initial combination, the second slot for the first round and so on. 185 */ 186 int aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key, 187 unsigned int key_len) 188 { 189 u32 kwords = key_len / sizeof(u32); 190 u32 rc, i, j; 191 int err; 192 193 err = aes_check_keylen(key_len); 194 if (err) 195 return err; 196 197 ctx->key_length = key_len; 198 199 for (i = 0; i < kwords; i++) 200 ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32)); 201 202 for (i = 0, rc = 1; i < 10; i++, rc = mul_by_x(rc)) { 203 u32 *rki = ctx->key_enc + (i * kwords); 204 u32 *rko = rki + kwords; 205 206 rko[0] = ror32(subw(rki[kwords - 1]), 8) ^ rc ^ rki[0]; 207 rko[1] = rko[0] ^ rki[1]; 208 rko[2] = rko[1] ^ rki[2]; 209 rko[3] = rko[2] ^ rki[3]; 210 211 if (key_len == AES_KEYSIZE_192) { 212 if (i >= 7) 213 break; 214 rko[4] = rko[3] ^ rki[4]; 215 rko[5] = rko[4] ^ rki[5]; 216 } else if (key_len == AES_KEYSIZE_256) { 217 if (i >= 6) 218 break; 219 rko[4] = subw(rko[3]) ^ rki[4]; 220 rko[5] = rko[4] ^ rki[5]; 221 rko[6] = rko[5] ^ rki[6]; 222 rko[7] = rko[6] ^ rki[7]; 223 } 224 } 225 226 /* 227 * Generate the decryption keys for the Equivalent Inverse Cipher. 228 * This involves reversing the order of the round keys, and applying 229 * the Inverse Mix Columns transformation to all but the first and 230 * the last one. 231 */ 232 ctx->key_dec[0] = ctx->key_enc[key_len + 24]; 233 ctx->key_dec[1] = ctx->key_enc[key_len + 25]; 234 ctx->key_dec[2] = ctx->key_enc[key_len + 26]; 235 ctx->key_dec[3] = ctx->key_enc[key_len + 27]; 236 237 for (i = 4, j = key_len + 20; j > 0; i += 4, j -= 4) { 238 ctx->key_dec[i] = inv_mix_columns(ctx->key_enc[j]); 239 ctx->key_dec[i + 1] = inv_mix_columns(ctx->key_enc[j + 1]); 240 ctx->key_dec[i + 2] = inv_mix_columns(ctx->key_enc[j + 2]); 241 ctx->key_dec[i + 3] = inv_mix_columns(ctx->key_enc[j + 3]); 242 } 243 244 ctx->key_dec[i] = ctx->key_enc[0]; 245 ctx->key_dec[i + 1] = ctx->key_enc[1]; 246 ctx->key_dec[i + 2] = ctx->key_enc[2]; 247 ctx->key_dec[i + 3] = ctx->key_enc[3]; 248 249 return 0; 250 } 251 EXPORT_SYMBOL(aes_expandkey); 252 253 /** 254 * aes_encrypt - Encrypt a single AES block 255 * @ctx: Context struct containing the key schedule 256 * @out: Buffer to store the ciphertext 257 * @in: Buffer containing the plaintext 258 */ 259 void aes_encrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in) 260 { 261 const u32 *rkp = ctx->key_enc + 4; 262 int rounds = 6 + ctx->key_length / 4; 263 u32 st0[4], st1[4]; 264 int round; 265 266 st0[0] = ctx->key_enc[0] ^ get_unaligned_le32(in); 267 st0[1] = ctx->key_enc[1] ^ get_unaligned_le32(in + 4); 268 st0[2] = ctx->key_enc[2] ^ get_unaligned_le32(in + 8); 269 st0[3] = ctx->key_enc[3] ^ get_unaligned_le32(in + 12); 270 271 /* 272 * Force the compiler to emit data independent Sbox references, 273 * by xoring the input with Sbox values that are known to add up 274 * to zero. This pulls the entire Sbox into the D-cache before any 275 * data dependent lookups are done. 276 */ 277 st0[0] ^= aes_sbox[ 0] ^ aes_sbox[ 64] ^ aes_sbox[134] ^ aes_sbox[195]; 278 st0[1] ^= aes_sbox[16] ^ aes_sbox[ 82] ^ aes_sbox[158] ^ aes_sbox[221]; 279 st0[2] ^= aes_sbox[32] ^ aes_sbox[ 96] ^ aes_sbox[160] ^ aes_sbox[234]; 280 st0[3] ^= aes_sbox[48] ^ aes_sbox[112] ^ aes_sbox[186] ^ aes_sbox[241]; 281 282 for (round = 0;; round += 2, rkp += 8) { 283 st1[0] = mix_columns(subshift(st0, 0)) ^ rkp[0]; 284 st1[1] = mix_columns(subshift(st0, 1)) ^ rkp[1]; 285 st1[2] = mix_columns(subshift(st0, 2)) ^ rkp[2]; 286 st1[3] = mix_columns(subshift(st0, 3)) ^ rkp[3]; 287 288 if (round == rounds - 2) 289 break; 290 291 st0[0] = mix_columns(subshift(st1, 0)) ^ rkp[4]; 292 st0[1] = mix_columns(subshift(st1, 1)) ^ rkp[5]; 293 st0[2] = mix_columns(subshift(st1, 2)) ^ rkp[6]; 294 st0[3] = mix_columns(subshift(st1, 3)) ^ rkp[7]; 295 } 296 297 put_unaligned_le32(subshift(st1, 0) ^ rkp[4], out); 298 put_unaligned_le32(subshift(st1, 1) ^ rkp[5], out + 4); 299 put_unaligned_le32(subshift(st1, 2) ^ rkp[6], out + 8); 300 put_unaligned_le32(subshift(st1, 3) ^ rkp[7], out + 12); 301 } 302 EXPORT_SYMBOL(aes_encrypt); 303 304 /** 305 * aes_decrypt - Decrypt a single AES block 306 * @ctx: Context struct containing the key schedule 307 * @out: Buffer to store the plaintext 308 * @in: Buffer containing the ciphertext 309 */ 310 void aes_decrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in) 311 { 312 const u32 *rkp = ctx->key_dec + 4; 313 int rounds = 6 + ctx->key_length / 4; 314 u32 st0[4], st1[4]; 315 int round; 316 317 st0[0] = ctx->key_dec[0] ^ get_unaligned_le32(in); 318 st0[1] = ctx->key_dec[1] ^ get_unaligned_le32(in + 4); 319 st0[2] = ctx->key_dec[2] ^ get_unaligned_le32(in + 8); 320 st0[3] = ctx->key_dec[3] ^ get_unaligned_le32(in + 12); 321 322 /* 323 * Force the compiler to emit data independent Sbox references, 324 * by xoring the input with Sbox values that are known to add up 325 * to zero. This pulls the entire Sbox into the D-cache before any 326 * data dependent lookups are done. 327 */ 328 st0[0] ^= aes_inv_sbox[ 0] ^ aes_inv_sbox[ 64] ^ aes_inv_sbox[129] ^ aes_inv_sbox[200]; 329 st0[1] ^= aes_inv_sbox[16] ^ aes_inv_sbox[ 83] ^ aes_inv_sbox[150] ^ aes_inv_sbox[212]; 330 st0[2] ^= aes_inv_sbox[32] ^ aes_inv_sbox[ 96] ^ aes_inv_sbox[160] ^ aes_inv_sbox[236]; 331 st0[3] ^= aes_inv_sbox[48] ^ aes_inv_sbox[112] ^ aes_inv_sbox[187] ^ aes_inv_sbox[247]; 332 333 for (round = 0;; round += 2, rkp += 8) { 334 st1[0] = inv_mix_columns(inv_subshift(st0, 0)) ^ rkp[0]; 335 st1[1] = inv_mix_columns(inv_subshift(st0, 1)) ^ rkp[1]; 336 st1[2] = inv_mix_columns(inv_subshift(st0, 2)) ^ rkp[2]; 337 st1[3] = inv_mix_columns(inv_subshift(st0, 3)) ^ rkp[3]; 338 339 if (round == rounds - 2) 340 break; 341 342 st0[0] = inv_mix_columns(inv_subshift(st1, 0)) ^ rkp[4]; 343 st0[1] = inv_mix_columns(inv_subshift(st1, 1)) ^ rkp[5]; 344 st0[2] = inv_mix_columns(inv_subshift(st1, 2)) ^ rkp[6]; 345 st0[3] = inv_mix_columns(inv_subshift(st1, 3)) ^ rkp[7]; 346 } 347 348 put_unaligned_le32(inv_subshift(st1, 0) ^ rkp[4], out); 349 put_unaligned_le32(inv_subshift(st1, 1) ^ rkp[5], out + 4); 350 put_unaligned_le32(inv_subshift(st1, 2) ^ rkp[6], out + 8); 351 put_unaligned_le32(inv_subshift(st1, 3) ^ rkp[7], out + 12); 352 } 353 EXPORT_SYMBOL(aes_decrypt); 354 355 MODULE_DESCRIPTION("Generic AES library"); 356 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); 357 MODULE_LICENSE("GPL v2"); 358