aes.c (12475B)
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/module.h> 9#include <asm/unaligned.h> 10 11/* 12 * Emit the sbox as volatile const to prevent the compiler from doing 13 * constant folding on sbox references involving fixed indexes. 14 */ 15static volatile const u8 __cacheline_aligned aes_sbox[] = { 16 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 17 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, 18 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 19 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, 20 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 21 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, 22 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 23 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, 24 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 25 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, 26 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 27 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, 28 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 29 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, 30 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 31 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, 32 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 33 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, 34 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 35 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, 36 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 37 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, 38 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 39 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, 40 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 41 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, 42 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 43 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, 44 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 45 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, 46 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 47 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16, 48}; 49 50static volatile const u8 __cacheline_aligned aes_inv_sbox[] = { 51 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 52 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb, 53 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 54 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb, 55 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 56 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e, 57 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 58 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25, 59 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 60 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92, 61 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 62 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84, 63 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 64 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06, 65 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 66 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b, 67 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 68 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73, 69 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 70 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e, 71 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 72 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b, 73 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 74 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4, 75 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 76 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f, 77 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 78 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef, 79 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 80 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61, 81 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 82 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d, 83}; 84 85extern const u8 crypto_aes_sbox[256] __alias(aes_sbox); 86extern const u8 crypto_aes_inv_sbox[256] __alias(aes_inv_sbox); 87 88EXPORT_SYMBOL(crypto_aes_sbox); 89EXPORT_SYMBOL(crypto_aes_inv_sbox); 90 91static u32 mul_by_x(u32 w) 92{ 93 u32 x = w & 0x7f7f7f7f; 94 u32 y = w & 0x80808080; 95 96 /* multiply by polynomial 'x' (0b10) in GF(2^8) */ 97 return (x << 1) ^ (y >> 7) * 0x1b; 98} 99 100static u32 mul_by_x2(u32 w) 101{ 102 u32 x = w & 0x3f3f3f3f; 103 u32 y = w & 0x80808080; 104 u32 z = w & 0x40404040; 105 106 /* multiply by polynomial 'x^2' (0b100) in GF(2^8) */ 107 return (x << 2) ^ (y >> 7) * 0x36 ^ (z >> 6) * 0x1b; 108} 109 110static u32 mix_columns(u32 x) 111{ 112 /* 113 * Perform the following matrix multiplication in GF(2^8) 114 * 115 * | 0x2 0x3 0x1 0x1 | | x[0] | 116 * | 0x1 0x2 0x3 0x1 | | x[1] | 117 * | 0x1 0x1 0x2 0x3 | x | x[2] | 118 * | 0x3 0x1 0x1 0x2 | | x[3] | 119 */ 120 u32 y = mul_by_x(x) ^ ror32(x, 16); 121 122 return y ^ ror32(x ^ y, 8); 123} 124 125static u32 inv_mix_columns(u32 x) 126{ 127 /* 128 * Perform the following matrix multiplication in GF(2^8) 129 * 130 * | 0xe 0xb 0xd 0x9 | | x[0] | 131 * | 0x9 0xe 0xb 0xd | | x[1] | 132 * | 0xd 0x9 0xe 0xb | x | x[2] | 133 * | 0xb 0xd 0x9 0xe | | x[3] | 134 * 135 * which can conveniently be reduced to 136 * 137 * | 0x2 0x3 0x1 0x1 | | 0x5 0x0 0x4 0x0 | | x[0] | 138 * | 0x1 0x2 0x3 0x1 | | 0x0 0x5 0x0 0x4 | | x[1] | 139 * | 0x1 0x1 0x2 0x3 | x | 0x4 0x0 0x5 0x0 | x | x[2] | 140 * | 0x3 0x1 0x1 0x2 | | 0x0 0x4 0x0 0x5 | | x[3] | 141 */ 142 u32 y = mul_by_x2(x); 143 144 return mix_columns(x ^ y ^ ror32(y, 16)); 145} 146 147static __always_inline u32 subshift(u32 in[], int pos) 148{ 149 return (aes_sbox[in[pos] & 0xff]) ^ 150 (aes_sbox[(in[(pos + 1) % 4] >> 8) & 0xff] << 8) ^ 151 (aes_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^ 152 (aes_sbox[(in[(pos + 3) % 4] >> 24) & 0xff] << 24); 153} 154 155static __always_inline u32 inv_subshift(u32 in[], int pos) 156{ 157 return (aes_inv_sbox[in[pos] & 0xff]) ^ 158 (aes_inv_sbox[(in[(pos + 3) % 4] >> 8) & 0xff] << 8) ^ 159 (aes_inv_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^ 160 (aes_inv_sbox[(in[(pos + 1) % 4] >> 24) & 0xff] << 24); 161} 162 163static u32 subw(u32 in) 164{ 165 return (aes_sbox[in & 0xff]) ^ 166 (aes_sbox[(in >> 8) & 0xff] << 8) ^ 167 (aes_sbox[(in >> 16) & 0xff] << 16) ^ 168 (aes_sbox[(in >> 24) & 0xff] << 24); 169} 170 171/** 172 * aes_expandkey - Expands the AES key as described in FIPS-197 173 * @ctx: The location where the computed key will be stored. 174 * @in_key: The supplied key. 175 * @key_len: The length of the supplied key. 176 * 177 * Returns 0 on success. The function fails only if an invalid key size (or 178 * pointer) is supplied. 179 * The expanded key size is 240 bytes (max of 14 rounds with a unique 16 bytes 180 * key schedule plus a 16 bytes key which is used before the first round). 181 * The decryption key is prepared for the "Equivalent Inverse Cipher" as 182 * described in FIPS-197. The first slot (16 bytes) of each key (enc or dec) is 183 * for the initial combination, the second slot for the first round and so on. 184 */ 185int aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key, 186 unsigned int key_len) 187{ 188 u32 kwords = key_len / sizeof(u32); 189 u32 rc, i, j; 190 int err; 191 192 err = aes_check_keylen(key_len); 193 if (err) 194 return err; 195 196 ctx->key_length = key_len; 197 198 for (i = 0; i < kwords; i++) 199 ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32)); 200 201 for (i = 0, rc = 1; i < 10; i++, rc = mul_by_x(rc)) { 202 u32 *rki = ctx->key_enc + (i * kwords); 203 u32 *rko = rki + kwords; 204 205 rko[0] = ror32(subw(rki[kwords - 1]), 8) ^ rc ^ rki[0]; 206 rko[1] = rko[0] ^ rki[1]; 207 rko[2] = rko[1] ^ rki[2]; 208 rko[3] = rko[2] ^ rki[3]; 209 210 if (key_len == AES_KEYSIZE_192) { 211 if (i >= 7) 212 break; 213 rko[4] = rko[3] ^ rki[4]; 214 rko[5] = rko[4] ^ rki[5]; 215 } else if (key_len == AES_KEYSIZE_256) { 216 if (i >= 6) 217 break; 218 rko[4] = subw(rko[3]) ^ rki[4]; 219 rko[5] = rko[4] ^ rki[5]; 220 rko[6] = rko[5] ^ rki[6]; 221 rko[7] = rko[6] ^ rki[7]; 222 } 223 } 224 225 /* 226 * Generate the decryption keys for the Equivalent Inverse Cipher. 227 * This involves reversing the order of the round keys, and applying 228 * the Inverse Mix Columns transformation to all but the first and 229 * the last one. 230 */ 231 ctx->key_dec[0] = ctx->key_enc[key_len + 24]; 232 ctx->key_dec[1] = ctx->key_enc[key_len + 25]; 233 ctx->key_dec[2] = ctx->key_enc[key_len + 26]; 234 ctx->key_dec[3] = ctx->key_enc[key_len + 27]; 235 236 for (i = 4, j = key_len + 20; j > 0; i += 4, j -= 4) { 237 ctx->key_dec[i] = inv_mix_columns(ctx->key_enc[j]); 238 ctx->key_dec[i + 1] = inv_mix_columns(ctx->key_enc[j + 1]); 239 ctx->key_dec[i + 2] = inv_mix_columns(ctx->key_enc[j + 2]); 240 ctx->key_dec[i + 3] = inv_mix_columns(ctx->key_enc[j + 3]); 241 } 242 243 ctx->key_dec[i] = ctx->key_enc[0]; 244 ctx->key_dec[i + 1] = ctx->key_enc[1]; 245 ctx->key_dec[i + 2] = ctx->key_enc[2]; 246 ctx->key_dec[i + 3] = ctx->key_enc[3]; 247 248 return 0; 249} 250EXPORT_SYMBOL(aes_expandkey); 251 252/** 253 * aes_encrypt - Encrypt a single AES block 254 * @ctx: Context struct containing the key schedule 255 * @out: Buffer to store the ciphertext 256 * @in: Buffer containing the plaintext 257 */ 258void aes_encrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in) 259{ 260 const u32 *rkp = ctx->key_enc + 4; 261 int rounds = 6 + ctx->key_length / 4; 262 u32 st0[4], st1[4]; 263 int round; 264 265 st0[0] = ctx->key_enc[0] ^ get_unaligned_le32(in); 266 st0[1] = ctx->key_enc[1] ^ get_unaligned_le32(in + 4); 267 st0[2] = ctx->key_enc[2] ^ get_unaligned_le32(in + 8); 268 st0[3] = ctx->key_enc[3] ^ get_unaligned_le32(in + 12); 269 270 /* 271 * Force the compiler to emit data independent Sbox references, 272 * by xoring the input with Sbox values that are known to add up 273 * to zero. This pulls the entire Sbox into the D-cache before any 274 * data dependent lookups are done. 275 */ 276 st0[0] ^= aes_sbox[ 0] ^ aes_sbox[ 64] ^ aes_sbox[134] ^ aes_sbox[195]; 277 st0[1] ^= aes_sbox[16] ^ aes_sbox[ 82] ^ aes_sbox[158] ^ aes_sbox[221]; 278 st0[2] ^= aes_sbox[32] ^ aes_sbox[ 96] ^ aes_sbox[160] ^ aes_sbox[234]; 279 st0[3] ^= aes_sbox[48] ^ aes_sbox[112] ^ aes_sbox[186] ^ aes_sbox[241]; 280 281 for (round = 0;; round += 2, rkp += 8) { 282 st1[0] = mix_columns(subshift(st0, 0)) ^ rkp[0]; 283 st1[1] = mix_columns(subshift(st0, 1)) ^ rkp[1]; 284 st1[2] = mix_columns(subshift(st0, 2)) ^ rkp[2]; 285 st1[3] = mix_columns(subshift(st0, 3)) ^ rkp[3]; 286 287 if (round == rounds - 2) 288 break; 289 290 st0[0] = mix_columns(subshift(st1, 0)) ^ rkp[4]; 291 st0[1] = mix_columns(subshift(st1, 1)) ^ rkp[5]; 292 st0[2] = mix_columns(subshift(st1, 2)) ^ rkp[6]; 293 st0[3] = mix_columns(subshift(st1, 3)) ^ rkp[7]; 294 } 295 296 put_unaligned_le32(subshift(st1, 0) ^ rkp[4], out); 297 put_unaligned_le32(subshift(st1, 1) ^ rkp[5], out + 4); 298 put_unaligned_le32(subshift(st1, 2) ^ rkp[6], out + 8); 299 put_unaligned_le32(subshift(st1, 3) ^ rkp[7], out + 12); 300} 301EXPORT_SYMBOL(aes_encrypt); 302 303/** 304 * aes_decrypt - Decrypt a single AES block 305 * @ctx: Context struct containing the key schedule 306 * @out: Buffer to store the plaintext 307 * @in: Buffer containing the ciphertext 308 */ 309void aes_decrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in) 310{ 311 const u32 *rkp = ctx->key_dec + 4; 312 int rounds = 6 + ctx->key_length / 4; 313 u32 st0[4], st1[4]; 314 int round; 315 316 st0[0] = ctx->key_dec[0] ^ get_unaligned_le32(in); 317 st0[1] = ctx->key_dec[1] ^ get_unaligned_le32(in + 4); 318 st0[2] = ctx->key_dec[2] ^ get_unaligned_le32(in + 8); 319 st0[3] = ctx->key_dec[3] ^ get_unaligned_le32(in + 12); 320 321 /* 322 * Force the compiler to emit data independent Sbox references, 323 * by xoring the input with Sbox values that are known to add up 324 * to zero. This pulls the entire Sbox into the D-cache before any 325 * data dependent lookups are done. 326 */ 327 st0[0] ^= aes_inv_sbox[ 0] ^ aes_inv_sbox[ 64] ^ aes_inv_sbox[129] ^ aes_inv_sbox[200]; 328 st0[1] ^= aes_inv_sbox[16] ^ aes_inv_sbox[ 83] ^ aes_inv_sbox[150] ^ aes_inv_sbox[212]; 329 st0[2] ^= aes_inv_sbox[32] ^ aes_inv_sbox[ 96] ^ aes_inv_sbox[160] ^ aes_inv_sbox[236]; 330 st0[3] ^= aes_inv_sbox[48] ^ aes_inv_sbox[112] ^ aes_inv_sbox[187] ^ aes_inv_sbox[247]; 331 332 for (round = 0;; round += 2, rkp += 8) { 333 st1[0] = inv_mix_columns(inv_subshift(st0, 0)) ^ rkp[0]; 334 st1[1] = inv_mix_columns(inv_subshift(st0, 1)) ^ rkp[1]; 335 st1[2] = inv_mix_columns(inv_subshift(st0, 2)) ^ rkp[2]; 336 st1[3] = inv_mix_columns(inv_subshift(st0, 3)) ^ rkp[3]; 337 338 if (round == rounds - 2) 339 break; 340 341 st0[0] = inv_mix_columns(inv_subshift(st1, 0)) ^ rkp[4]; 342 st0[1] = inv_mix_columns(inv_subshift(st1, 1)) ^ rkp[5]; 343 st0[2] = inv_mix_columns(inv_subshift(st1, 2)) ^ rkp[6]; 344 st0[3] = inv_mix_columns(inv_subshift(st1, 3)) ^ rkp[7]; 345 } 346 347 put_unaligned_le32(inv_subshift(st1, 0) ^ rkp[4], out); 348 put_unaligned_le32(inv_subshift(st1, 1) ^ rkp[5], out + 4); 349 put_unaligned_le32(inv_subshift(st1, 2) ^ rkp[6], out + 8); 350 put_unaligned_le32(inv_subshift(st1, 3) ^ rkp[7], out + 12); 351} 352EXPORT_SYMBOL(aes_decrypt); 353 354MODULE_DESCRIPTION("Generic AES library"); 355MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); 356MODULE_LICENSE("GPL v2");