| /* 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/aead.h> |
| #include <openssl/cipher.h> |
| #include <openssl/crypto.h> |
| #include <openssl/err.h> |
| #include <openssl/sha.h> |
| |
| #include "../fipsmodule/cipher/internal.h" |
| |
| |
| #define EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN SHA256_DIGEST_LENGTH |
| #define EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN 12 |
| |
| struct aead_aes_ctr_hmac_sha256_ctx { |
| union { |
| double align; |
| AES_KEY ks; |
| } ks; |
| ctr128_f ctr; |
| block128_f block; |
| SHA256_CTX inner_init_state; |
| SHA256_CTX outer_init_state; |
| }; |
| |
| OPENSSL_COMPILE_ASSERT(sizeof(((EVP_AEAD_CTX *)NULL)->state) >= |
| sizeof(struct aead_aes_ctr_hmac_sha256_ctx), |
| AEAD_state_too_small); |
| #if defined(__GNUC__) || defined(__clang__) |
| OPENSSL_COMPILE_ASSERT(alignof(union evp_aead_ctx_st_state) >= |
| alignof(struct aead_aes_ctr_hmac_sha256_ctx), |
| AEAD_state_insufficient_alignment); |
| #endif |
| |
| static void hmac_init(SHA256_CTX *out_inner, SHA256_CTX *out_outer, |
| const uint8_t hmac_key[32]) { |
| static const size_t hmac_key_len = 32; |
| uint8_t block[SHA256_CBLOCK]; |
| OPENSSL_memcpy(block, hmac_key, hmac_key_len); |
| OPENSSL_memset(block + hmac_key_len, 0x36, sizeof(block) - hmac_key_len); |
| |
| unsigned i; |
| for (i = 0; i < hmac_key_len; i++) { |
| block[i] ^= 0x36; |
| } |
| |
| SHA256_Init(out_inner); |
| SHA256_Update(out_inner, block, sizeof(block)); |
| |
| OPENSSL_memset(block + hmac_key_len, 0x5c, sizeof(block) - hmac_key_len); |
| for (i = 0; i < hmac_key_len; i++) { |
| block[i] ^= (0x36 ^ 0x5c); |
| } |
| |
| SHA256_Init(out_outer); |
| SHA256_Update(out_outer, block, sizeof(block)); |
| } |
| |
| static int aead_aes_ctr_hmac_sha256_init(EVP_AEAD_CTX *ctx, const uint8_t *key, |
| size_t key_len, size_t tag_len) { |
| struct aead_aes_ctr_hmac_sha256_ctx *aes_ctx = |
| (struct aead_aes_ctr_hmac_sha256_ctx *)&ctx->state; |
| static const size_t hmac_key_len = 32; |
| |
| if (key_len < hmac_key_len) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH); |
| return 0; // EVP_AEAD_CTX_init should catch this. |
| } |
| |
| const size_t aes_key_len = key_len - hmac_key_len; |
| if (aes_key_len != 16 && aes_key_len != 32) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH); |
| return 0; // EVP_AEAD_CTX_init should catch this. |
| } |
| |
| if (tag_len == EVP_AEAD_DEFAULT_TAG_LENGTH) { |
| tag_len = EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN; |
| } |
| |
| if (tag_len > EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TAG_TOO_LARGE); |
| return 0; |
| } |
| |
| aes_ctx->ctr = |
| aes_ctr_set_key(&aes_ctx->ks.ks, NULL, &aes_ctx->block, key, aes_key_len); |
| ctx->tag_len = tag_len; |
| hmac_init(&aes_ctx->inner_init_state, &aes_ctx->outer_init_state, |
| key + aes_key_len); |
| |
| return 1; |
| } |
| |
| static void aead_aes_ctr_hmac_sha256_cleanup(EVP_AEAD_CTX *ctx) {} |
| |
| static void hmac_update_uint64(SHA256_CTX *sha256, uint64_t value) { |
| unsigned i; |
| uint8_t bytes[8]; |
| |
| for (i = 0; i < sizeof(bytes); i++) { |
| bytes[i] = value & 0xff; |
| value >>= 8; |
| } |
| SHA256_Update(sha256, bytes, sizeof(bytes)); |
| } |
| |
| static void hmac_calculate(uint8_t out[SHA256_DIGEST_LENGTH], |
| const SHA256_CTX *inner_init_state, |
| const SHA256_CTX *outer_init_state, |
| const uint8_t *ad, size_t ad_len, |
| const uint8_t *nonce, const uint8_t *ciphertext, |
| size_t ciphertext_len) { |
| SHA256_CTX sha256; |
| OPENSSL_memcpy(&sha256, inner_init_state, sizeof(sha256)); |
| hmac_update_uint64(&sha256, ad_len); |
| hmac_update_uint64(&sha256, ciphertext_len); |
| SHA256_Update(&sha256, nonce, EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN); |
| SHA256_Update(&sha256, ad, ad_len); |
| |
| // Pad with zeros to the end of the SHA-256 block. |
| const unsigned num_padding = |
| (SHA256_CBLOCK - ((sizeof(uint64_t)*2 + |
| EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN + ad_len) % |
| SHA256_CBLOCK)) % |
| SHA256_CBLOCK; |
| uint8_t padding[SHA256_CBLOCK]; |
| OPENSSL_memset(padding, 0, num_padding); |
| SHA256_Update(&sha256, padding, num_padding); |
| |
| SHA256_Update(&sha256, ciphertext, ciphertext_len); |
| |
| uint8_t inner_digest[SHA256_DIGEST_LENGTH]; |
| SHA256_Final(inner_digest, &sha256); |
| |
| OPENSSL_memcpy(&sha256, outer_init_state, sizeof(sha256)); |
| SHA256_Update(&sha256, inner_digest, sizeof(inner_digest)); |
| SHA256_Final(out, &sha256); |
| } |
| |
| static void aead_aes_ctr_hmac_sha256_crypt( |
| const struct aead_aes_ctr_hmac_sha256_ctx *aes_ctx, uint8_t *out, |
| const uint8_t *in, size_t len, const uint8_t *nonce) { |
| // Since the AEAD operation is one-shot, keeping a buffer of unused keystream |
| // bytes is pointless. However, |CRYPTO_ctr128_encrypt| requires it. |
| uint8_t partial_block_buffer[AES_BLOCK_SIZE]; |
| unsigned partial_block_offset = 0; |
| OPENSSL_memset(partial_block_buffer, 0, sizeof(partial_block_buffer)); |
| |
| uint8_t counter[AES_BLOCK_SIZE]; |
| OPENSSL_memcpy(counter, nonce, EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN); |
| OPENSSL_memset(counter + EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN, 0, 4); |
| |
| if (aes_ctx->ctr) { |
| CRYPTO_ctr128_encrypt_ctr32(in, out, len, &aes_ctx->ks.ks, counter, |
| partial_block_buffer, &partial_block_offset, |
| aes_ctx->ctr); |
| } else { |
| CRYPTO_ctr128_encrypt(in, out, len, &aes_ctx->ks.ks, counter, |
| partial_block_buffer, &partial_block_offset, |
| aes_ctx->block); |
| } |
| } |
| |
| static int aead_aes_ctr_hmac_sha256_seal_scatter( |
| const EVP_AEAD_CTX *ctx, uint8_t *out, uint8_t *out_tag, |
| size_t *out_tag_len, size_t max_out_tag_len, const uint8_t *nonce, |
| size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *extra_in, |
| size_t extra_in_len, const uint8_t *ad, size_t ad_len) { |
| const struct aead_aes_ctr_hmac_sha256_ctx *aes_ctx = |
| (struct aead_aes_ctr_hmac_sha256_ctx *) &ctx->state; |
| const uint64_t in_len_64 = in_len; |
| |
| if (in_len_64 >= (UINT64_C(1) << 32) * AES_BLOCK_SIZE) { |
| // This input is so large it would overflow the 32-bit block counter. |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); |
| return 0; |
| } |
| |
| if (max_out_tag_len < ctx->tag_len) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL); |
| return 0; |
| } |
| |
| if (nonce_len != EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); |
| return 0; |
| } |
| |
| aead_aes_ctr_hmac_sha256_crypt(aes_ctx, out, in, in_len, nonce); |
| |
| uint8_t hmac_result[SHA256_DIGEST_LENGTH]; |
| hmac_calculate(hmac_result, &aes_ctx->inner_init_state, |
| &aes_ctx->outer_init_state, ad, ad_len, nonce, out, in_len); |
| OPENSSL_memcpy(out_tag, hmac_result, ctx->tag_len); |
| *out_tag_len = ctx->tag_len; |
| |
| return 1; |
| } |
| |
| static int aead_aes_ctr_hmac_sha256_open_gather( |
| const EVP_AEAD_CTX *ctx, uint8_t *out, const uint8_t *nonce, |
| size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *in_tag, |
| size_t in_tag_len, const uint8_t *ad, size_t ad_len) { |
| const struct aead_aes_ctr_hmac_sha256_ctx *aes_ctx = |
| (struct aead_aes_ctr_hmac_sha256_ctx *) &ctx->state; |
| |
| if (in_tag_len != ctx->tag_len) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); |
| return 0; |
| } |
| |
| if (nonce_len != EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); |
| return 0; |
| } |
| |
| uint8_t hmac_result[SHA256_DIGEST_LENGTH]; |
| hmac_calculate(hmac_result, &aes_ctx->inner_init_state, |
| &aes_ctx->outer_init_state, ad, ad_len, nonce, in, |
| in_len); |
| if (CRYPTO_memcmp(hmac_result, in_tag, ctx->tag_len) != 0) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); |
| return 0; |
| } |
| |
| aead_aes_ctr_hmac_sha256_crypt(aes_ctx, out, in, in_len, nonce); |
| |
| return 1; |
| } |
| |
| static const EVP_AEAD aead_aes_128_ctr_hmac_sha256 = { |
| 16 /* AES key */ + 32 /* HMAC key */, |
| 12, // nonce length |
| EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN, // overhead |
| EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN, // max tag length |
| 0, // seal_scatter_supports_extra_in |
| |
| aead_aes_ctr_hmac_sha256_init, |
| NULL /* init_with_direction */, |
| aead_aes_ctr_hmac_sha256_cleanup, |
| NULL /* open */, |
| aead_aes_ctr_hmac_sha256_seal_scatter, |
| aead_aes_ctr_hmac_sha256_open_gather, |
| NULL /* get_iv */, |
| NULL /* tag_len */, |
| }; |
| |
| static const EVP_AEAD aead_aes_256_ctr_hmac_sha256 = { |
| 32 /* AES key */ + 32 /* HMAC key */, |
| 12, // nonce length |
| EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN, // overhead |
| EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN, // max tag length |
| 0, // seal_scatter_supports_extra_in |
| |
| aead_aes_ctr_hmac_sha256_init, |
| NULL /* init_with_direction */, |
| aead_aes_ctr_hmac_sha256_cleanup, |
| NULL /* open */, |
| aead_aes_ctr_hmac_sha256_seal_scatter, |
| aead_aes_ctr_hmac_sha256_open_gather, |
| NULL /* get_iv */, |
| NULL /* tag_len */, |
| }; |
| |
| const EVP_AEAD *EVP_aead_aes_128_ctr_hmac_sha256(void) { |
| return &aead_aes_128_ctr_hmac_sha256; |
| } |
| |
| const EVP_AEAD *EVP_aead_aes_256_ctr_hmac_sha256(void) { |
| return &aead_aes_256_ctr_hmac_sha256; |
| } |