| /* Copyright (c) 2017, Google Inc. |
| * |
| * Permission to use, copy, modify, and/or distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
| * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |
| * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
| * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ |
| |
| #include <openssl/rand.h> |
| |
| #include <openssl/type_check.h> |
| #include <openssl/mem.h> |
| |
| #include "internal.h" |
| #include "../cipher/internal.h" |
| #include "../service_indicator/internal.h" |
| |
| |
| // Section references in this file refer to SP 800-90Ar1: |
| // http://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-90Ar1.pdf |
| |
| // See table 3. |
| static const uint64_t kMaxReseedCount = UINT64_C(1) << 48; |
| |
| int CTR_DRBG_init(CTR_DRBG_STATE *drbg, |
| const uint8_t entropy[CTR_DRBG_ENTROPY_LEN], |
| const uint8_t *personalization, size_t personalization_len) { |
| // Section 10.2.1.3.1 |
| if (personalization_len > CTR_DRBG_ENTROPY_LEN) { |
| return 0; |
| } |
| |
| uint8_t seed_material[CTR_DRBG_ENTROPY_LEN]; |
| OPENSSL_memcpy(seed_material, entropy, CTR_DRBG_ENTROPY_LEN); |
| |
| for (size_t i = 0; i < personalization_len; i++) { |
| seed_material[i] ^= personalization[i]; |
| } |
| |
| // Section 10.2.1.2 |
| |
| // kInitMask is the result of encrypting blocks with big-endian value 1, 2 |
| // and 3 with the all-zero AES-256 key. |
| static const uint8_t kInitMask[CTR_DRBG_ENTROPY_LEN] = { |
| 0x53, 0x0f, 0x8a, 0xfb, 0xc7, 0x45, 0x36, 0xb9, 0xa9, 0x63, 0xb4, 0xf1, |
| 0xc4, 0xcb, 0x73, 0x8b, 0xce, 0xa7, 0x40, 0x3d, 0x4d, 0x60, 0x6b, 0x6e, |
| 0x07, 0x4e, 0xc5, 0xd3, 0xba, 0xf3, 0x9d, 0x18, 0x72, 0x60, 0x03, 0xca, |
| 0x37, 0xa6, 0x2a, 0x74, 0xd1, 0xa2, 0xf5, 0x8e, 0x75, 0x06, 0x35, 0x8e, |
| }; |
| |
| for (size_t i = 0; i < sizeof(kInitMask); i++) { |
| seed_material[i] ^= kInitMask[i]; |
| } |
| |
| drbg->ctr = aes_ctr_set_key(&drbg->ks, NULL, &drbg->block, seed_material, 32); |
| OPENSSL_memcpy(drbg->counter.bytes, seed_material + 32, 16); |
| drbg->reseed_counter = 1; |
| |
| return 1; |
| } |
| |
| OPENSSL_STATIC_ASSERT(CTR_DRBG_ENTROPY_LEN % AES_BLOCK_SIZE == 0, |
| "not a multiple of AES block size"); |
| |
| // ctr_inc adds |n| to the last four bytes of |drbg->counter|, treated as a |
| // big-endian number. |
| static void ctr32_add(CTR_DRBG_STATE *drbg, uint32_t n) { |
| drbg->counter.words[3] = |
| CRYPTO_bswap4(CRYPTO_bswap4(drbg->counter.words[3]) + n); |
| } |
| |
| static int ctr_drbg_update(CTR_DRBG_STATE *drbg, const uint8_t *data, |
| size_t data_len) { |
| // Per section 10.2.1.2, |data_len| must be |CTR_DRBG_ENTROPY_LEN|. Here, we |
| // allow shorter inputs and right-pad them with zeros. This is equivalent to |
| // the specified algorithm but saves a copy in |CTR_DRBG_generate|. |
| if (data_len > CTR_DRBG_ENTROPY_LEN) { |
| return 0; |
| } |
| |
| uint8_t temp[CTR_DRBG_ENTROPY_LEN]; |
| for (size_t i = 0; i < CTR_DRBG_ENTROPY_LEN; i += AES_BLOCK_SIZE) { |
| ctr32_add(drbg, 1); |
| drbg->block(drbg->counter.bytes, temp + i, &drbg->ks); |
| } |
| |
| for (size_t i = 0; i < data_len; i++) { |
| temp[i] ^= data[i]; |
| } |
| |
| drbg->ctr = aes_ctr_set_key(&drbg->ks, NULL, &drbg->block, temp, 32); |
| OPENSSL_memcpy(drbg->counter.bytes, temp + 32, 16); |
| |
| return 1; |
| } |
| |
| int CTR_DRBG_reseed(CTR_DRBG_STATE *drbg, |
| const uint8_t entropy[CTR_DRBG_ENTROPY_LEN], |
| const uint8_t *additional_data, |
| size_t additional_data_len) { |
| // Section 10.2.1.4 |
| uint8_t entropy_copy[CTR_DRBG_ENTROPY_LEN]; |
| |
| if (additional_data_len > 0) { |
| if (additional_data_len > CTR_DRBG_ENTROPY_LEN) { |
| return 0; |
| } |
| |
| OPENSSL_memcpy(entropy_copy, entropy, CTR_DRBG_ENTROPY_LEN); |
| for (size_t i = 0; i < additional_data_len; i++) { |
| entropy_copy[i] ^= additional_data[i]; |
| } |
| |
| entropy = entropy_copy; |
| } |
| |
| if (!ctr_drbg_update(drbg, entropy, CTR_DRBG_ENTROPY_LEN)) { |
| return 0; |
| } |
| |
| drbg->reseed_counter = 1; |
| |
| return 1; |
| } |
| |
| int CTR_DRBG_generate(CTR_DRBG_STATE *drbg, uint8_t *out, size_t out_len, |
| const uint8_t *additional_data, |
| size_t additional_data_len) { |
| // See 9.3.1 |
| if (out_len > CTR_DRBG_MAX_GENERATE_LENGTH) { |
| return 0; |
| } |
| |
| // See 10.2.1.5.1 |
| if (drbg->reseed_counter > kMaxReseedCount) { |
| return 0; |
| } |
| |
| if (additional_data_len != 0 && |
| !ctr_drbg_update(drbg, additional_data, additional_data_len)) { |
| return 0; |
| } |
| |
| // kChunkSize is used to interact better with the cache. Since the AES-CTR |
| // code assumes that it's encrypting rather than just writing keystream, the |
| // buffer has to be zeroed first. Without chunking, large reads would zero |
| // the whole buffer, flushing the L1 cache, and then do another pass (missing |
| // the cache every time) to “encrypt” it. The code can avoid this by |
| // chunking. |
| static const size_t kChunkSize = 8 * 1024; |
| |
| while (out_len >= AES_BLOCK_SIZE) { |
| size_t todo = kChunkSize; |
| if (todo > out_len) { |
| todo = out_len; |
| } |
| |
| todo &= ~(AES_BLOCK_SIZE-1); |
| const size_t num_blocks = todo / AES_BLOCK_SIZE; |
| |
| if (drbg->ctr) { |
| OPENSSL_memset(out, 0, todo); |
| ctr32_add(drbg, 1); |
| drbg->ctr(out, out, num_blocks, &drbg->ks, drbg->counter.bytes); |
| ctr32_add(drbg, num_blocks - 1); |
| } else { |
| for (size_t i = 0; i < todo; i += AES_BLOCK_SIZE) { |
| ctr32_add(drbg, 1); |
| drbg->block(drbg->counter.bytes, out + i, &drbg->ks); |
| } |
| } |
| |
| out += todo; |
| out_len -= todo; |
| } |
| |
| if (out_len > 0) { |
| uint8_t block[AES_BLOCK_SIZE]; |
| ctr32_add(drbg, 1); |
| drbg->block(drbg->counter.bytes, block, &drbg->ks); |
| |
| OPENSSL_memcpy(out, block, out_len); |
| } |
| |
| // Right-padding |additional_data| in step 2.2 is handled implicitly by |
| // |ctr_drbg_update|, to save a copy. |
| if (!ctr_drbg_update(drbg, additional_data, additional_data_len)) { |
| return 0; |
| } |
| |
| drbg->reseed_counter++; |
| FIPS_service_indicator_update_state(); |
| return 1; |
| } |
| |
| void CTR_DRBG_clear(CTR_DRBG_STATE *drbg) { |
| OPENSSL_cleanse(drbg, sizeof(CTR_DRBG_STATE)); |
| } |