1 /* Copyright (c) 2017, Google Inc. 2 * 3 * Permission to use, copy, modify, and/or distribute this software for any 4 * purpose with or without fee is hereby granted, provided that the above 5 * copyright notice and this permission notice appear in all copies. 6 * 7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ 14 15 #include <openssl/aead.h> 16 17 #include <assert.h> 18 19 #include <openssl/cipher.h> 20 #include <openssl/cpu.h> 21 #include <openssl/crypto.h> 22 #include <openssl/err.h> 23 24 #include "../fipsmodule/cipher/internal.h" 25 26 27 #define EVP_AEAD_AES_GCM_SIV_NONCE_LEN 12 28 #define EVP_AEAD_AES_GCM_SIV_TAG_LEN 16 29 30 #if defined(OPENSSL_X86_64) && !defined(OPENSSL_NO_ASM) 31 32 // Optimised AES-GCM-SIV 33 34 struct aead_aes_gcm_siv_asm_ctx { 35 alignas(16) uint8_t key[16*15]; 36 int is_128_bit; 37 // ptr contains the original pointer from |OPENSSL_malloc|, which may only be 38 // 8-byte aligned. When freeing this structure, actually call |OPENSSL_free| 39 // on this pointer. 40 void *ptr; 41 }; 42 43 // aes128gcmsiv_aes_ks writes an AES-128 key schedule for |key| to 44 // |out_expanded_key|. 45 extern void aes128gcmsiv_aes_ks( 46 const uint8_t key[16], uint8_t out_expanded_key[16*15]); 47 48 // aes128gcmsiv_aes_ks writes an AES-128 key schedule for |key| to 49 // |out_expanded_key|. 50 extern void aes256gcmsiv_aes_ks( 51 const uint8_t key[16], uint8_t out_expanded_key[16*15]); 52 53 static int aead_aes_gcm_siv_asm_init(EVP_AEAD_CTX *ctx, const uint8_t *key, 54 size_t key_len, size_t tag_len) { 55 const size_t key_bits = key_len * 8; 56 57 if (key_bits != 128 && key_bits != 256) { 58 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH); 59 return 0; // EVP_AEAD_CTX_init should catch this. 60 } 61 62 if (tag_len == EVP_AEAD_DEFAULT_TAG_LENGTH) { 63 tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN; 64 } 65 66 if (tag_len != EVP_AEAD_AES_GCM_SIV_TAG_LEN) { 67 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TAG_TOO_LARGE); 68 return 0; 69 } 70 71 char *ptr = OPENSSL_malloc(sizeof(struct aead_aes_gcm_siv_asm_ctx) + 8); 72 if (ptr == NULL) { 73 return 0; 74 } 75 assert((((uintptr_t)ptr) & 7) == 0); 76 77 // gcm_siv_ctx needs to be 16-byte aligned in a cross-platform way. 78 struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx = 79 (struct aead_aes_gcm_siv_asm_ctx *)(ptr + (((uintptr_t)ptr) & 8)); 80 81 assert((((uintptr_t)gcm_siv_ctx) & 15) == 0); 82 gcm_siv_ctx->ptr = ptr; 83 84 if (key_bits == 128) { 85 aes128gcmsiv_aes_ks(key, &gcm_siv_ctx->key[0]); 86 gcm_siv_ctx->is_128_bit = 1; 87 } else { 88 aes256gcmsiv_aes_ks(key, &gcm_siv_ctx->key[0]); 89 gcm_siv_ctx->is_128_bit = 0; 90 } 91 ctx->aead_state = gcm_siv_ctx; 92 ctx->tag_len = tag_len; 93 94 return 1; 95 } 96 97 static void aead_aes_gcm_siv_asm_cleanup(EVP_AEAD_CTX *ctx) { 98 const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx = ctx->aead_state; 99 OPENSSL_free(gcm_siv_ctx->ptr); 100 } 101 102 // aesgcmsiv_polyval_horner updates the POLYVAL value in |in_out_poly| to 103 // include a number (|in_blocks|) of 16-byte blocks of data from |in|, given 104 // the POLYVAL key in |key|. 105 extern void aesgcmsiv_polyval_horner(const uint8_t in_out_poly[16], 106 const uint8_t key[16], const uint8_t *in, 107 size_t in_blocks); 108 109 // aesgcmsiv_htable_init writes powers 1..8 of |auth_key| to |out_htable|. 110 extern void aesgcmsiv_htable_init(uint8_t out_htable[16 * 8], 111 const uint8_t auth_key[16]); 112 113 // aesgcmsiv_htable6_init writes powers 1..6 of |auth_key| to |out_htable|. 114 extern void aesgcmsiv_htable6_init(uint8_t out_htable[16 * 6], 115 const uint8_t auth_key[16]); 116 117 // aesgcmsiv_htable_polyval updates the POLYVAL value in |in_out_poly| to 118 // include |in_len| bytes of data from |in|. (Where |in_len| must be a multiple 119 // of 16.) It uses the precomputed powers of the key given in |htable|. 120 extern void aesgcmsiv_htable_polyval(const uint8_t htable[16 * 8], 121 const uint8_t *in, size_t in_len, 122 uint8_t in_out_poly[16]); 123 124 // aes128gcmsiv_dec decrypts |in_len| & ~15 bytes from |out| and writes them to 125 // |in|. (The full value of |in_len| is still used to find the authentication 126 // tag appended to the ciphertext, however, so must not be pre-masked.) 127 // 128 // |in| and |out| may be equal, but must not otherwise overlap. 129 // 130 // While decrypting, it updates the POLYVAL value found at the beginning of 131 // |in_out_calculated_tag_and_scratch| and writes the updated value back before 132 // return. During executation, it may use the whole of this space for other 133 // purposes. In order to decrypt and update the POLYVAL value, it uses the 134 // expanded key from |key| and the table of powers in |htable|. 135 extern void aes128gcmsiv_dec(const uint8_t *in, uint8_t *out, 136 uint8_t in_out_calculated_tag_and_scratch[16 * 8], 137 const uint8_t htable[16 * 6], 138 const struct aead_aes_gcm_siv_asm_ctx *key, 139 size_t in_len); 140 141 // aes256gcmsiv_dec acts like |aes128gcmsiv_dec|, but for AES-256. 142 extern void aes256gcmsiv_dec(const uint8_t *in, uint8_t *out, 143 uint8_t in_out_calculated_tag_and_scratch[16 * 8], 144 const uint8_t htable[16 * 6], 145 const struct aead_aes_gcm_siv_asm_ctx *key, 146 size_t in_len); 147 148 // aes128gcmsiv_kdf performs the AES-GCM-SIV KDF given the expanded key from 149 // |key_schedule| and the nonce in |nonce|. Note that, while only 12 bytes of 150 // the nonce are used, 16 bytes are read and so the value must be 151 // right-padded. 152 extern void aes128gcmsiv_kdf(const uint8_t nonce[16], 153 uint64_t out_key_material[8], 154 const uint8_t *key_schedule); 155 156 // aes256gcmsiv_kdf acts like |aes128gcmsiv_kdf|, but for AES-256. 157 extern void aes256gcmsiv_kdf(const uint8_t nonce[16], 158 uint64_t out_key_material[12], 159 const uint8_t *key_schedule); 160 161 // aes128gcmsiv_aes_ks_enc_x1 performs a key expansion of the AES-128 key in 162 // |key|, writes the expanded key to |out_expanded_key| and encrypts a single 163 // block from |in| to |out|. 164 extern void aes128gcmsiv_aes_ks_enc_x1(const uint8_t in[16], uint8_t out[16], 165 uint8_t out_expanded_key[16 * 15], 166 const uint64_t key[2]); 167 168 // aes256gcmsiv_aes_ks_enc_x1 acts like |aes128gcmsiv_aes_ks_enc_x1|, but for 169 // AES-256. 170 extern void aes256gcmsiv_aes_ks_enc_x1(const uint8_t in[16], uint8_t out[16], 171 uint8_t out_expanded_key[16 * 15], 172 const uint64_t key[4]); 173 174 // aes128gcmsiv_ecb_enc_block encrypts a single block from |in| to |out| using 175 // the expanded key in |expanded_key|. 176 extern void aes128gcmsiv_ecb_enc_block( 177 const uint8_t in[16], uint8_t out[16], 178 const struct aead_aes_gcm_siv_asm_ctx *expanded_key); 179 180 // aes256gcmsiv_ecb_enc_block acts like |aes128gcmsiv_ecb_enc_block|, but for 181 // AES-256. 182 extern void aes256gcmsiv_ecb_enc_block( 183 const uint8_t in[16], uint8_t out[16], 184 const struct aead_aes_gcm_siv_asm_ctx *expanded_key); 185 186 // aes128gcmsiv_enc_msg_x4 encrypts |in_len| bytes from |in| to |out| using the 187 // expanded key from |key|. (The value of |in_len| must be a multiple of 16.) 188 // The |in| and |out| buffers may be equal but must not otherwise overlap. The 189 // initial counter is constructed from the given |tag| as required by 190 // AES-GCM-SIV. 191 extern void aes128gcmsiv_enc_msg_x4(const uint8_t *in, uint8_t *out, 192 const uint8_t *tag, 193 const struct aead_aes_gcm_siv_asm_ctx *key, 194 size_t in_len); 195 196 // aes256gcmsiv_enc_msg_x4 acts like |aes128gcmsiv_enc_msg_x4|, but for 197 // AES-256. 198 extern void aes256gcmsiv_enc_msg_x4(const uint8_t *in, uint8_t *out, 199 const uint8_t *tag, 200 const struct aead_aes_gcm_siv_asm_ctx *key, 201 size_t in_len); 202 203 // aes128gcmsiv_enc_msg_x8 acts like |aes128gcmsiv_enc_msg_x4|, but is 204 // optimised for longer messages. 205 extern void aes128gcmsiv_enc_msg_x8(const uint8_t *in, uint8_t *out, 206 const uint8_t *tag, 207 const struct aead_aes_gcm_siv_asm_ctx *key, 208 size_t in_len); 209 210 // aes256gcmsiv_enc_msg_x8 acts like |aes256gcmsiv_enc_msg_x4|, but is 211 // optimised for longer messages. 212 extern void aes256gcmsiv_enc_msg_x8(const uint8_t *in, uint8_t *out, 213 const uint8_t *tag, 214 const struct aead_aes_gcm_siv_asm_ctx *key, 215 size_t in_len); 216 217 // gcm_siv_asm_polyval evaluates POLYVAL at |auth_key| on the given plaintext 218 // and AD. The result is written to |out_tag|. 219 static void gcm_siv_asm_polyval(uint8_t out_tag[16], const uint8_t *in, 220 size_t in_len, const uint8_t *ad, size_t ad_len, 221 const uint8_t auth_key[16], 222 const uint8_t nonce[12]) { 223 OPENSSL_memset(out_tag, 0, 16); 224 const size_t ad_blocks = ad_len / 16; 225 const size_t in_blocks = in_len / 16; 226 int htable_init = 0; 227 alignas(16) uint8_t htable[16*8]; 228 229 if (ad_blocks > 8 || in_blocks > 8) { 230 htable_init = 1; 231 aesgcmsiv_htable_init(htable, auth_key); 232 } 233 234 if (htable_init) { 235 aesgcmsiv_htable_polyval(htable, ad, ad_len & ~15, out_tag); 236 } else { 237 aesgcmsiv_polyval_horner(out_tag, auth_key, ad, ad_blocks); 238 } 239 240 uint8_t scratch[16]; 241 if (ad_len & 15) { 242 OPENSSL_memset(scratch, 0, sizeof(scratch)); 243 OPENSSL_memcpy(scratch, &ad[ad_len & ~15], ad_len & 15); 244 aesgcmsiv_polyval_horner(out_tag, auth_key, scratch, 1); 245 } 246 247 if (htable_init) { 248 aesgcmsiv_htable_polyval(htable, in, in_len & ~15, out_tag); 249 } else { 250 aesgcmsiv_polyval_horner(out_tag, auth_key, in, in_blocks); 251 } 252 253 if (in_len & 15) { 254 OPENSSL_memset(scratch, 0, sizeof(scratch)); 255 OPENSSL_memcpy(scratch, &in[in_len & ~15], in_len & 15); 256 aesgcmsiv_polyval_horner(out_tag, auth_key, scratch, 1); 257 } 258 259 union { 260 uint8_t c[16]; 261 struct { 262 uint64_t ad; 263 uint64_t in; 264 } bitlens; 265 } length_block; 266 267 length_block.bitlens.ad = ad_len * 8; 268 length_block.bitlens.in = in_len * 8; 269 aesgcmsiv_polyval_horner(out_tag, auth_key, length_block.c, 1); 270 271 for (size_t i = 0; i < 12; i++) { 272 out_tag[i] ^= nonce[i]; 273 } 274 275 out_tag[15] &= 0x7f; 276 } 277 278 // aead_aes_gcm_siv_asm_crypt_last_block handles the encryption/decryption 279 // (same thing in CTR mode) of the final block of a plaintext/ciphertext. It 280 // writes |in_len| & 15 bytes to |out| + |in_len|, based on an initial counter 281 // derived from |tag|. 282 static void aead_aes_gcm_siv_asm_crypt_last_block( 283 int is_128_bit, uint8_t *out, const uint8_t *in, size_t in_len, 284 const uint8_t tag[16], 285 const struct aead_aes_gcm_siv_asm_ctx *enc_key_expanded) { 286 alignas(16) union { 287 uint8_t c[16]; 288 uint32_t u32[4]; 289 } counter; 290 OPENSSL_memcpy(&counter, tag, sizeof(counter)); 291 counter.c[15] |= 0x80; 292 counter.u32[0] += in_len / 16; 293 294 if (is_128_bit) { 295 aes128gcmsiv_ecb_enc_block(&counter.c[0], &counter.c[0], enc_key_expanded); 296 } else { 297 aes256gcmsiv_ecb_enc_block(&counter.c[0], &counter.c[0], enc_key_expanded); 298 } 299 300 const size_t last_bytes_offset = in_len & ~15; 301 const size_t last_bytes_len = in_len & 15; 302 uint8_t *last_bytes_out = &out[last_bytes_offset]; 303 const uint8_t *last_bytes_in = &in[last_bytes_offset]; 304 for (size_t i = 0; i < last_bytes_len; i++) { 305 last_bytes_out[i] = last_bytes_in[i] ^ counter.c[i]; 306 } 307 } 308 309 // aead_aes_gcm_siv_kdf calculates the record encryption and authentication 310 // keys given the |nonce|. 311 static void aead_aes_gcm_siv_kdf( 312 int is_128_bit, const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx, 313 uint64_t out_record_auth_key[2], uint64_t out_record_enc_key[4], 314 const uint8_t nonce[12]) { 315 alignas(16) uint8_t padded_nonce[16]; 316 OPENSSL_memcpy(padded_nonce, nonce, 12); 317 318 alignas(16) uint64_t key_material[12]; 319 if (is_128_bit) { 320 aes128gcmsiv_kdf(padded_nonce, key_material, &gcm_siv_ctx->key[0]); 321 out_record_enc_key[0] = key_material[4]; 322 out_record_enc_key[1] = key_material[6]; 323 } else { 324 aes256gcmsiv_kdf(padded_nonce, key_material, &gcm_siv_ctx->key[0]); 325 out_record_enc_key[0] = key_material[4]; 326 out_record_enc_key[1] = key_material[6]; 327 out_record_enc_key[2] = key_material[8]; 328 out_record_enc_key[3] = key_material[10]; 329 } 330 331 out_record_auth_key[0] = key_material[0]; 332 out_record_auth_key[1] = key_material[2]; 333 } 334 335 static int aead_aes_gcm_siv_asm_seal_scatter( 336 const EVP_AEAD_CTX *ctx, uint8_t *out, uint8_t *out_tag, 337 size_t *out_tag_len, size_t max_out_tag_len, const uint8_t *nonce, 338 size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *extra_in, 339 size_t extra_in_len, const uint8_t *ad, size_t ad_len) { 340 const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx = ctx->aead_state; 341 const uint64_t in_len_64 = in_len; 342 const uint64_t ad_len_64 = ad_len; 343 344 if (in_len_64 > (UINT64_C(1) << 36) || 345 ad_len_64 >= (UINT64_C(1) << 61)) { 346 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); 347 return 0; 348 } 349 350 if (max_out_tag_len < EVP_AEAD_AES_GCM_SIV_TAG_LEN) { 351 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL); 352 return 0; 353 } 354 355 if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) { 356 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); 357 return 0; 358 } 359 360 alignas(16) uint64_t record_auth_key[2]; 361 alignas(16) uint64_t record_enc_key[4]; 362 aead_aes_gcm_siv_kdf(gcm_siv_ctx->is_128_bit, gcm_siv_ctx, record_auth_key, 363 record_enc_key, nonce); 364 365 alignas(16) uint8_t tag[16] = {0}; 366 gcm_siv_asm_polyval(tag, in, in_len, ad, ad_len, 367 (const uint8_t *)record_auth_key, nonce); 368 369 struct aead_aes_gcm_siv_asm_ctx enc_key_expanded; 370 371 if (gcm_siv_ctx->is_128_bit) { 372 aes128gcmsiv_aes_ks_enc_x1(tag, tag, &enc_key_expanded.key[0], 373 record_enc_key); 374 375 if (in_len < 128) { 376 aes128gcmsiv_enc_msg_x4(in, out, tag, &enc_key_expanded, in_len & ~15); 377 } else { 378 aes128gcmsiv_enc_msg_x8(in, out, tag, &enc_key_expanded, in_len & ~15); 379 } 380 } else { 381 aes256gcmsiv_aes_ks_enc_x1(tag, tag, &enc_key_expanded.key[0], 382 record_enc_key); 383 384 if (in_len < 128) { 385 aes256gcmsiv_enc_msg_x4(in, out, tag, &enc_key_expanded, in_len & ~15); 386 } else { 387 aes256gcmsiv_enc_msg_x8(in, out, tag, &enc_key_expanded, in_len & ~15); 388 } 389 } 390 391 if (in_len & 15) { 392 aead_aes_gcm_siv_asm_crypt_last_block(gcm_siv_ctx->is_128_bit, out, in, 393 in_len, tag, &enc_key_expanded); 394 } 395 396 OPENSSL_memcpy(out_tag, tag, sizeof(tag)); 397 *out_tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN; 398 399 return 1; 400 } 401 402 // TODO(martinkr): Add aead_aes_gcm_siv_asm_open_gather. N.B. aes128gcmsiv_dec 403 // expects ciphertext and tag in a contiguous buffer. 404 405 static int aead_aes_gcm_siv_asm_open(const EVP_AEAD_CTX *ctx, uint8_t *out, 406 size_t *out_len, size_t max_out_len, 407 const uint8_t *nonce, size_t nonce_len, 408 const uint8_t *in, size_t in_len, 409 const uint8_t *ad, size_t ad_len) { 410 const uint64_t ad_len_64 = ad_len; 411 if (ad_len_64 >= (UINT64_C(1) << 61)) { 412 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); 413 return 0; 414 } 415 416 const uint64_t in_len_64 = in_len; 417 if (in_len < EVP_AEAD_AES_GCM_SIV_TAG_LEN || 418 in_len_64 > (UINT64_C(1) << 36) + AES_BLOCK_SIZE) { 419 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); 420 return 0; 421 } 422 423 const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx = ctx->aead_state; 424 const size_t plaintext_len = in_len - EVP_AEAD_AES_GCM_SIV_TAG_LEN; 425 const uint8_t *const given_tag = in + plaintext_len; 426 427 if (max_out_len < plaintext_len) { 428 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL); 429 return 0; 430 } 431 432 alignas(16) uint64_t record_auth_key[2]; 433 alignas(16) uint64_t record_enc_key[4]; 434 aead_aes_gcm_siv_kdf(gcm_siv_ctx->is_128_bit, gcm_siv_ctx, record_auth_key, 435 record_enc_key, nonce); 436 437 struct aead_aes_gcm_siv_asm_ctx expanded_key; 438 if (gcm_siv_ctx->is_128_bit) { 439 aes128gcmsiv_aes_ks((const uint8_t *) record_enc_key, &expanded_key.key[0]); 440 } else { 441 aes256gcmsiv_aes_ks((const uint8_t *) record_enc_key, &expanded_key.key[0]); 442 } 443 // calculated_tag is 16*8 bytes, rather than 16 bytes, because 444 // aes[128|256]gcmsiv_dec uses the extra as scratch space. 445 alignas(16) uint8_t calculated_tag[16 * 8] = {0}; 446 447 OPENSSL_memset(calculated_tag, 0, EVP_AEAD_AES_GCM_SIV_TAG_LEN); 448 const size_t ad_blocks = ad_len / 16; 449 aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key, ad, 450 ad_blocks); 451 452 uint8_t scratch[16]; 453 if (ad_len & 15) { 454 OPENSSL_memset(scratch, 0, sizeof(scratch)); 455 OPENSSL_memcpy(scratch, &ad[ad_len & ~15], ad_len & 15); 456 aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key, 457 scratch, 1); 458 } 459 460 alignas(16) uint8_t htable[16 * 6]; 461 aesgcmsiv_htable6_init(htable, (const uint8_t *)record_auth_key); 462 463 if (gcm_siv_ctx->is_128_bit) { 464 aes128gcmsiv_dec(in, out, calculated_tag, htable, &expanded_key, 465 plaintext_len); 466 } else { 467 aes256gcmsiv_dec(in, out, calculated_tag, htable, &expanded_key, 468 plaintext_len); 469 } 470 471 if (plaintext_len & 15) { 472 aead_aes_gcm_siv_asm_crypt_last_block(gcm_siv_ctx->is_128_bit, out, in, 473 plaintext_len, given_tag, 474 &expanded_key); 475 OPENSSL_memset(scratch, 0, sizeof(scratch)); 476 OPENSSL_memcpy(scratch, out + (plaintext_len & ~15), plaintext_len & 15); 477 aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key, 478 scratch, 1); 479 } 480 481 union { 482 uint8_t c[16]; 483 struct { 484 uint64_t ad; 485 uint64_t in; 486 } bitlens; 487 } length_block; 488 489 length_block.bitlens.ad = ad_len * 8; 490 length_block.bitlens.in = plaintext_len * 8; 491 aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key, 492 length_block.c, 1); 493 494 for (size_t i = 0; i < 12; i++) { 495 calculated_tag[i] ^= nonce[i]; 496 } 497 498 calculated_tag[15] &= 0x7f; 499 500 if (gcm_siv_ctx->is_128_bit) { 501 aes128gcmsiv_ecb_enc_block(calculated_tag, calculated_tag, &expanded_key); 502 } else { 503 aes256gcmsiv_ecb_enc_block(calculated_tag, calculated_tag, &expanded_key); 504 } 505 506 if (CRYPTO_memcmp(calculated_tag, given_tag, EVP_AEAD_AES_GCM_SIV_TAG_LEN) != 507 0) { 508 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); 509 return 0; 510 } 511 512 *out_len = in_len - EVP_AEAD_AES_GCM_SIV_TAG_LEN; 513 return 1; 514 } 515 516 static const EVP_AEAD aead_aes_128_gcm_siv_asm = { 517 16, // key length 518 EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length 519 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead 520 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length 521 0, // seal_scatter_supports_extra_in 522 523 aead_aes_gcm_siv_asm_init, 524 NULL /* init_with_direction */, 525 aead_aes_gcm_siv_asm_cleanup, 526 aead_aes_gcm_siv_asm_open, 527 aead_aes_gcm_siv_asm_seal_scatter, 528 NULL /* open_gather */, 529 NULL /* get_iv */, 530 NULL /* tag_len */, 531 }; 532 533 static const EVP_AEAD aead_aes_256_gcm_siv_asm = { 534 32, // key length 535 EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length 536 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead 537 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length 538 0, // seal_scatter_supports_extra_in 539 540 aead_aes_gcm_siv_asm_init, 541 NULL /* init_with_direction */, 542 aead_aes_gcm_siv_asm_cleanup, 543 aead_aes_gcm_siv_asm_open, 544 aead_aes_gcm_siv_asm_seal_scatter, 545 NULL /* open_gather */, 546 NULL /* get_iv */, 547 NULL /* tag_len */, 548 }; 549 550 #endif // X86_64 && !NO_ASM 551 552 struct aead_aes_gcm_siv_ctx { 553 union { 554 double align; 555 AES_KEY ks; 556 } ks; 557 block128_f kgk_block; 558 unsigned is_256:1; 559 }; 560 561 static int aead_aes_gcm_siv_init(EVP_AEAD_CTX *ctx, const uint8_t *key, 562 size_t key_len, size_t tag_len) { 563 const size_t key_bits = key_len * 8; 564 565 if (key_bits != 128 && key_bits != 256) { 566 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH); 567 return 0; // EVP_AEAD_CTX_init should catch this. 568 } 569 570 if (tag_len == EVP_AEAD_DEFAULT_TAG_LENGTH) { 571 tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN; 572 } 573 if (tag_len != EVP_AEAD_AES_GCM_SIV_TAG_LEN) { 574 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TAG_TOO_LARGE); 575 return 0; 576 } 577 578 struct aead_aes_gcm_siv_ctx *gcm_siv_ctx = 579 OPENSSL_malloc(sizeof(struct aead_aes_gcm_siv_ctx)); 580 if (gcm_siv_ctx == NULL) { 581 return 0; 582 } 583 OPENSSL_memset(gcm_siv_ctx, 0, sizeof(struct aead_aes_gcm_siv_ctx)); 584 585 aes_ctr_set_key(&gcm_siv_ctx->ks.ks, NULL, &gcm_siv_ctx->kgk_block, key, 586 key_len); 587 gcm_siv_ctx->is_256 = (key_len == 32); 588 ctx->aead_state = gcm_siv_ctx; 589 ctx->tag_len = tag_len; 590 591 return 1; 592 } 593 594 static void aead_aes_gcm_siv_cleanup(EVP_AEAD_CTX *ctx) { 595 OPENSSL_free(ctx->aead_state); 596 } 597 598 // gcm_siv_crypt encrypts (or decryptsit's the same thing) |in_len| bytes from 599 // |in| to |out|, using the block function |enc_block| with |key| in counter 600 // mode, starting at |initial_counter|. This differs from the traditional 601 // counter mode code in that the counter is handled little-endian, only the 602 // first four bytes are used and the GCM-SIV tweak to the final byte is 603 // applied. The |in| and |out| pointers may be equal but otherwise must not 604 // alias. 605 static void gcm_siv_crypt(uint8_t *out, const uint8_t *in, size_t in_len, 606 const uint8_t initial_counter[AES_BLOCK_SIZE], 607 block128_f enc_block, const AES_KEY *key) { 608 union { 609 uint32_t w[4]; 610 uint8_t c[16]; 611 } counter; 612 613 OPENSSL_memcpy(counter.c, initial_counter, AES_BLOCK_SIZE); 614 counter.c[15] |= 0x80; 615 616 for (size_t done = 0; done < in_len;) { 617 uint8_t keystream[AES_BLOCK_SIZE]; 618 enc_block(counter.c, keystream, key); 619 counter.w[0]++; 620 621 size_t todo = AES_BLOCK_SIZE; 622 if (in_len - done < todo) { 623 todo = in_len - done; 624 } 625 626 for (size_t i = 0; i < todo; i++) { 627 out[done + i] = keystream[i] ^ in[done + i]; 628 } 629 630 done += todo; 631 } 632 } 633 634 // gcm_siv_polyval evaluates POLYVAL at |auth_key| on the given plaintext and 635 // AD. The result is written to |out_tag|. 636 static void gcm_siv_polyval( 637 uint8_t out_tag[16], const uint8_t *in, size_t in_len, const uint8_t *ad, 638 size_t ad_len, const uint8_t auth_key[16], 639 const uint8_t nonce[EVP_AEAD_AES_GCM_SIV_NONCE_LEN]) { 640 struct polyval_ctx polyval_ctx; 641 CRYPTO_POLYVAL_init(&polyval_ctx, auth_key); 642 643 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, ad, ad_len & ~15); 644 645 uint8_t scratch[16]; 646 if (ad_len & 15) { 647 OPENSSL_memset(scratch, 0, sizeof(scratch)); 648 OPENSSL_memcpy(scratch, &ad[ad_len & ~15], ad_len & 15); 649 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, scratch, sizeof(scratch)); 650 } 651 652 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, in, in_len & ~15); 653 if (in_len & 15) { 654 OPENSSL_memset(scratch, 0, sizeof(scratch)); 655 OPENSSL_memcpy(scratch, &in[in_len & ~15], in_len & 15); 656 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, scratch, sizeof(scratch)); 657 } 658 659 union { 660 uint8_t c[16]; 661 struct { 662 uint64_t ad; 663 uint64_t in; 664 } bitlens; 665 } length_block; 666 667 length_block.bitlens.ad = ad_len * 8; 668 length_block.bitlens.in = in_len * 8; 669 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, length_block.c, 670 sizeof(length_block)); 671 672 CRYPTO_POLYVAL_finish(&polyval_ctx, out_tag); 673 for (size_t i = 0; i < EVP_AEAD_AES_GCM_SIV_NONCE_LEN; i++) { 674 out_tag[i] ^= nonce[i]; 675 } 676 out_tag[15] &= 0x7f; 677 } 678 679 // gcm_siv_record_keys contains the keys used for a specific GCM-SIV record. 680 struct gcm_siv_record_keys { 681 uint8_t auth_key[16]; 682 union { 683 double align; 684 AES_KEY ks; 685 } enc_key; 686 block128_f enc_block; 687 }; 688 689 // gcm_siv_keys calculates the keys for a specific GCM-SIV record with the 690 // given nonce and writes them to |*out_keys|. 691 static void gcm_siv_keys( 692 const struct aead_aes_gcm_siv_ctx *gcm_siv_ctx, 693 struct gcm_siv_record_keys *out_keys, 694 const uint8_t nonce[EVP_AEAD_AES_GCM_SIV_NONCE_LEN]) { 695 const AES_KEY *const key = &gcm_siv_ctx->ks.ks; 696 uint8_t key_material[(128 /* POLYVAL key */ + 256 /* max AES key */) / 8]; 697 const size_t blocks_needed = gcm_siv_ctx->is_256 ? 6 : 4; 698 699 uint8_t counter[AES_BLOCK_SIZE]; 700 OPENSSL_memset(counter, 0, AES_BLOCK_SIZE - EVP_AEAD_AES_GCM_SIV_NONCE_LEN); 701 OPENSSL_memcpy(counter + AES_BLOCK_SIZE - EVP_AEAD_AES_GCM_SIV_NONCE_LEN, 702 nonce, EVP_AEAD_AES_GCM_SIV_NONCE_LEN); 703 for (size_t i = 0; i < blocks_needed; i++) { 704 counter[0] = i; 705 706 uint8_t ciphertext[AES_BLOCK_SIZE]; 707 gcm_siv_ctx->kgk_block(counter, ciphertext, key); 708 OPENSSL_memcpy(&key_material[i * 8], ciphertext, 8); 709 } 710 711 OPENSSL_memcpy(out_keys->auth_key, key_material, 16); 712 aes_ctr_set_key(&out_keys->enc_key.ks, NULL, &out_keys->enc_block, 713 key_material + 16, gcm_siv_ctx->is_256 ? 32 : 16); 714 } 715 716 static int aead_aes_gcm_siv_seal_scatter( 717 const EVP_AEAD_CTX *ctx, uint8_t *out, uint8_t *out_tag, 718 size_t *out_tag_len, size_t max_out_tag_len, const uint8_t *nonce, 719 size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *extra_in, 720 size_t extra_in_len, const uint8_t *ad, size_t ad_len) { 721 const struct aead_aes_gcm_siv_ctx *gcm_siv_ctx = ctx->aead_state; 722 const uint64_t in_len_64 = in_len; 723 const uint64_t ad_len_64 = ad_len; 724 725 if (in_len + EVP_AEAD_AES_GCM_SIV_TAG_LEN < in_len || 726 in_len_64 > (UINT64_C(1) << 36) || 727 ad_len_64 >= (UINT64_C(1) << 61)) { 728 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); 729 return 0; 730 } 731 732 if (max_out_tag_len < EVP_AEAD_AES_GCM_SIV_TAG_LEN) { 733 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL); 734 return 0; 735 } 736 737 if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) { 738 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); 739 return 0; 740 } 741 742 struct gcm_siv_record_keys keys; 743 gcm_siv_keys(gcm_siv_ctx, &keys, nonce); 744 745 uint8_t tag[16]; 746 gcm_siv_polyval(tag, in, in_len, ad, ad_len, keys.auth_key, nonce); 747 keys.enc_block(tag, tag, &keys.enc_key.ks); 748 749 gcm_siv_crypt(out, in, in_len, tag, keys.enc_block, &keys.enc_key.ks); 750 751 OPENSSL_memcpy(out_tag, tag, EVP_AEAD_AES_GCM_SIV_TAG_LEN); 752 *out_tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN; 753 754 return 1; 755 } 756 757 static int aead_aes_gcm_siv_open_gather(const EVP_AEAD_CTX *ctx, uint8_t *out, 758 const uint8_t *nonce, size_t nonce_len, 759 const uint8_t *in, size_t in_len, 760 const uint8_t *in_tag, 761 size_t in_tag_len, const uint8_t *ad, 762 size_t ad_len) { 763 const uint64_t ad_len_64 = ad_len; 764 if (ad_len_64 >= (UINT64_C(1) << 61)) { 765 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); 766 return 0; 767 } 768 769 const uint64_t in_len_64 = in_len; 770 if (in_tag_len != EVP_AEAD_AES_GCM_SIV_TAG_LEN || 771 in_len_64 > (UINT64_C(1) << 36) + AES_BLOCK_SIZE) { 772 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); 773 return 0; 774 } 775 776 if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) { 777 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); 778 return 0; 779 } 780 781 const struct aead_aes_gcm_siv_ctx *gcm_siv_ctx = ctx->aead_state; 782 783 struct gcm_siv_record_keys keys; 784 gcm_siv_keys(gcm_siv_ctx, &keys, nonce); 785 786 gcm_siv_crypt(out, in, in_len, in_tag, keys.enc_block, &keys.enc_key.ks); 787 788 uint8_t expected_tag[EVP_AEAD_AES_GCM_SIV_TAG_LEN]; 789 gcm_siv_polyval(expected_tag, out, in_len, ad, ad_len, keys.auth_key, nonce); 790 keys.enc_block(expected_tag, expected_tag, &keys.enc_key.ks); 791 792 if (CRYPTO_memcmp(expected_tag, in_tag, sizeof(expected_tag)) != 0) { 793 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); 794 return 0; 795 } 796 797 return 1; 798 } 799 800 static const EVP_AEAD aead_aes_128_gcm_siv = { 801 16, // key length 802 EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length 803 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead 804 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length 805 0, // seal_scatter_supports_extra_in 806 807 aead_aes_gcm_siv_init, 808 NULL /* init_with_direction */, 809 aead_aes_gcm_siv_cleanup, 810 NULL /* open */, 811 aead_aes_gcm_siv_seal_scatter, 812 aead_aes_gcm_siv_open_gather, 813 NULL /* get_iv */, 814 NULL /* tag_len */, 815 }; 816 817 static const EVP_AEAD aead_aes_256_gcm_siv = { 818 32, // key length 819 EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length 820 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead 821 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length 822 0, // seal_scatter_supports_extra_in 823 824 aead_aes_gcm_siv_init, 825 NULL /* init_with_direction */, 826 aead_aes_gcm_siv_cleanup, 827 NULL /* open */, 828 aead_aes_gcm_siv_seal_scatter, 829 aead_aes_gcm_siv_open_gather, 830 NULL /* get_iv */, 831 NULL /* tag_len */, 832 }; 833 834 #if defined(OPENSSL_X86_64) && !defined(OPENSSL_NO_ASM) 835 836 static char avx_aesni_capable(void) { 837 const uint32_t ecx = OPENSSL_ia32cap_P[1]; 838 839 return (ecx & (1 << (57 - 32))) != 0 /* AESNI */ && 840 (ecx & (1 << 28)) != 0 /* AVX */; 841 } 842 843 const EVP_AEAD *EVP_aead_aes_128_gcm_siv(void) { 844 if (avx_aesni_capable()) { 845 return &aead_aes_128_gcm_siv_asm; 846 } 847 return &aead_aes_128_gcm_siv; 848 } 849 850 const EVP_AEAD *EVP_aead_aes_256_gcm_siv(void) { 851 if (avx_aesni_capable()) { 852 return &aead_aes_256_gcm_siv_asm; 853 } 854 return &aead_aes_256_gcm_siv; 855 } 856 857 #else 858 859 const EVP_AEAD *EVP_aead_aes_128_gcm_siv(void) { 860 return &aead_aes_128_gcm_siv; 861 } 862 863 const EVP_AEAD *EVP_aead_aes_256_gcm_siv(void) { 864 return &aead_aes_256_gcm_siv; 865 } 866 867 #endif // X86_64 && !NO_ASM 868
