/* 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_grpc/aead.h> #include <assert.h> #include <openssl_grpc/cipher.h> #include <openssl_grpc/cpu.h> #include <openssl_grpc/crypto.h> #include <openssl_grpc/err.h> #include "../fipsmodule/cipher/internal.h" #define EVP_AEAD_AES_GCM_SIV_NONCE_LEN 12 #define EVP_AEAD_AES_GCM_SIV_TAG_LEN 16 // TODO(davidben): AES-GCM-SIV assembly is not correct for Windows. It must save // and restore xmm6 through xmm15. #if defined(OPENSSL_X86_64) && !defined(OPENSSL_NO_ASM) && \ !defined(OPENSSL_WINDOWS) #define AES_GCM_SIV_ASM // Optimised AES-GCM-SIV struct aead_aes_gcm_siv_asm_ctx { alignas(16) uint8_t key[16*15]; int is_128_bit; }; // The assembly code assumes 8-byte alignment of the EVP_AEAD_CTX's state, and // aligns to 16 bytes itself. OPENSSL_STATIC_ASSERT(sizeof(((EVP_AEAD_CTX *)NULL)->state) + 8 >= sizeof(struct aead_aes_gcm_siv_asm_ctx), "AEAD state is too small"); #if defined(__GNUC__) || defined(__clang__) OPENSSL_STATIC_ASSERT(alignof(union evp_aead_ctx_st_state) >= 8, "AEAD state has insufficient alignment"); #endif // asm_ctx_from_ctx returns a 16-byte aligned context pointer from |ctx|. static struct aead_aes_gcm_siv_asm_ctx *asm_ctx_from_ctx( const EVP_AEAD_CTX *ctx) { // ctx->state must already be 8-byte aligned. Thus, at most, we may need to // add eight to align it to 16 bytes. const uintptr_t offset = ((uintptr_t)&ctx->state) & 8; return (struct aead_aes_gcm_siv_asm_ctx *)(&ctx->state.opaque[offset]); } // aes128gcmsiv_aes_ks writes an AES-128 key schedule for |key| to // |out_expanded_key|. extern void aes128gcmsiv_aes_ks( const uint8_t key[16], uint8_t out_expanded_key[16*15]); // aes256gcmsiv_aes_ks writes an AES-256 key schedule for |key| to // |out_expanded_key|. extern void aes256gcmsiv_aes_ks( const uint8_t key[32], uint8_t out_expanded_key[16*15]); static int aead_aes_gcm_siv_asm_init(EVP_AEAD_CTX *ctx, const uint8_t *key, size_t key_len, size_t tag_len) { const size_t key_bits = key_len * 8; if (key_bits != 128 && key_bits != 256) { 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_GCM_SIV_TAG_LEN; } if (tag_len != EVP_AEAD_AES_GCM_SIV_TAG_LEN) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TAG_TOO_LARGE); return 0; } struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx = asm_ctx_from_ctx(ctx); assert((((uintptr_t)gcm_siv_ctx) & 15) == 0); if (key_bits == 128) { aes128gcmsiv_aes_ks(key, &gcm_siv_ctx->key[0]); gcm_siv_ctx->is_128_bit = 1; } else { aes256gcmsiv_aes_ks(key, &gcm_siv_ctx->key[0]); gcm_siv_ctx->is_128_bit = 0; } ctx->tag_len = tag_len; return 1; } static void aead_aes_gcm_siv_asm_cleanup(EVP_AEAD_CTX *ctx) {} // aesgcmsiv_polyval_horner updates the POLYVAL value in |in_out_poly| to // include a number (|in_blocks|) of 16-byte blocks of data from |in|, given // the POLYVAL key in |key|. extern void aesgcmsiv_polyval_horner(const uint8_t in_out_poly[16], const uint8_t key[16], const uint8_t *in, size_t in_blocks); // aesgcmsiv_htable_init writes powers 1..8 of |auth_key| to |out_htable|. extern void aesgcmsiv_htable_init(uint8_t out_htable[16 * 8], const uint8_t auth_key[16]); // aesgcmsiv_htable6_init writes powers 1..6 of |auth_key| to |out_htable|. extern void aesgcmsiv_htable6_init(uint8_t out_htable[16 * 6], const uint8_t auth_key[16]); // aesgcmsiv_htable_polyval updates the POLYVAL value in |in_out_poly| to // include |in_len| bytes of data from |in|. (Where |in_len| must be a multiple // of 16.) It uses the precomputed powers of the key given in |htable|. extern void aesgcmsiv_htable_polyval(const uint8_t htable[16 * 8], const uint8_t *in, size_t in_len, uint8_t in_out_poly[16]); // aes128gcmsiv_dec decrypts |in_len| & ~15 bytes from |out| and writes them to // |in|. (The full value of |in_len| is still used to find the authentication // tag appended to the ciphertext, however, so must not be pre-masked.) // // |in| and |out| may be equal, but must not otherwise overlap. // // While decrypting, it updates the POLYVAL value found at the beginning of // |in_out_calculated_tag_and_scratch| and writes the updated value back before // return. During executation, it may use the whole of this space for other // purposes. In order to decrypt and update the POLYVAL value, it uses the // expanded key from |key| and the table of powers in |htable|. extern void aes128gcmsiv_dec(const uint8_t *in, uint8_t *out, uint8_t in_out_calculated_tag_and_scratch[16 * 8], const uint8_t htable[16 * 6], const struct aead_aes_gcm_siv_asm_ctx *key, size_t in_len); // aes256gcmsiv_dec acts like |aes128gcmsiv_dec|, but for AES-256. extern void aes256gcmsiv_dec(const uint8_t *in, uint8_t *out, uint8_t in_out_calculated_tag_and_scratch[16 * 8], const uint8_t htable[16 * 6], const struct aead_aes_gcm_siv_asm_ctx *key, size_t in_len); // aes128gcmsiv_kdf performs the AES-GCM-SIV KDF given the expanded key from // |key_schedule| and the nonce in |nonce|. Note that, while only 12 bytes of // the nonce are used, 16 bytes are read and so the value must be // right-padded. extern void aes128gcmsiv_kdf(const uint8_t nonce[16], uint64_t out_key_material[8], const uint8_t *key_schedule); // aes256gcmsiv_kdf acts like |aes128gcmsiv_kdf|, but for AES-256. extern void aes256gcmsiv_kdf(const uint8_t nonce[16], uint64_t out_key_material[12], const uint8_t *key_schedule); // aes128gcmsiv_aes_ks_enc_x1 performs a key expansion of the AES-128 key in // |key|, writes the expanded key to |out_expanded_key| and encrypts a single // block from |in| to |out|. extern void aes128gcmsiv_aes_ks_enc_x1(const uint8_t in[16], uint8_t out[16], uint8_t out_expanded_key[16 * 15], const uint64_t key[2]); // aes256gcmsiv_aes_ks_enc_x1 acts like |aes128gcmsiv_aes_ks_enc_x1|, but for // AES-256. extern void aes256gcmsiv_aes_ks_enc_x1(const uint8_t in[16], uint8_t out[16], uint8_t out_expanded_key[16 * 15], const uint64_t key[4]); // aes128gcmsiv_ecb_enc_block encrypts a single block from |in| to |out| using // the expanded key in |expanded_key|. extern void aes128gcmsiv_ecb_enc_block( const uint8_t in[16], uint8_t out[16], const struct aead_aes_gcm_siv_asm_ctx *expanded_key); // aes256gcmsiv_ecb_enc_block acts like |aes128gcmsiv_ecb_enc_block|, but for // AES-256. extern void aes256gcmsiv_ecb_enc_block( const uint8_t in[16], uint8_t out[16], const struct aead_aes_gcm_siv_asm_ctx *expanded_key); // aes128gcmsiv_enc_msg_x4 encrypts |in_len| bytes from |in| to |out| using the // expanded key from |key|. (The value of |in_len| must be a multiple of 16.) // The |in| and |out| buffers may be equal but must not otherwise overlap. The // initial counter is constructed from the given |tag| as required by // AES-GCM-SIV. extern void aes128gcmsiv_enc_msg_x4(const uint8_t *in, uint8_t *out, const uint8_t *tag, const struct aead_aes_gcm_siv_asm_ctx *key, size_t in_len); // aes256gcmsiv_enc_msg_x4 acts like |aes128gcmsiv_enc_msg_x4|, but for // AES-256. extern void aes256gcmsiv_enc_msg_x4(const uint8_t *in, uint8_t *out, const uint8_t *tag, const struct aead_aes_gcm_siv_asm_ctx *key, size_t in_len); // aes128gcmsiv_enc_msg_x8 acts like |aes128gcmsiv_enc_msg_x4|, but is // optimised for longer messages. extern void aes128gcmsiv_enc_msg_x8(const uint8_t *in, uint8_t *out, const uint8_t *tag, const struct aead_aes_gcm_siv_asm_ctx *key, size_t in_len); // aes256gcmsiv_enc_msg_x8 acts like |aes256gcmsiv_enc_msg_x4|, but is // optimised for longer messages. extern void aes256gcmsiv_enc_msg_x8(const uint8_t *in, uint8_t *out, const uint8_t *tag, const struct aead_aes_gcm_siv_asm_ctx *key, size_t in_len); // gcm_siv_asm_polyval evaluates POLYVAL at |auth_key| on the given plaintext // and AD. The result is written to |out_tag|. static void gcm_siv_asm_polyval(uint8_t out_tag[16], const uint8_t *in, size_t in_len, const uint8_t *ad, size_t ad_len, const uint8_t auth_key[16], const uint8_t nonce[12]) { OPENSSL_memset(out_tag, 0, 16); const size_t ad_blocks = ad_len / 16; const size_t in_blocks = in_len / 16; int htable_init = 0; alignas(16) uint8_t htable[16*8]; if (ad_blocks > 8 || in_blocks > 8) { htable_init = 1; aesgcmsiv_htable_init(htable, auth_key); } if (htable_init) { aesgcmsiv_htable_polyval(htable, ad, ad_len & ~15, out_tag); } else { aesgcmsiv_polyval_horner(out_tag, auth_key, ad, ad_blocks); } uint8_t scratch[16]; if (ad_len & 15) { OPENSSL_memset(scratch, 0, sizeof(scratch)); OPENSSL_memcpy(scratch, &ad[ad_len & ~15], ad_len & 15); aesgcmsiv_polyval_horner(out_tag, auth_key, scratch, 1); } if (htable_init) { aesgcmsiv_htable_polyval(htable, in, in_len & ~15, out_tag); } else { aesgcmsiv_polyval_horner(out_tag, auth_key, in, in_blocks); } if (in_len & 15) { OPENSSL_memset(scratch, 0, sizeof(scratch)); OPENSSL_memcpy(scratch, &in[in_len & ~15], in_len & 15); aesgcmsiv_polyval_horner(out_tag, auth_key, scratch, 1); } union { uint8_t c[16]; struct { uint64_t ad; uint64_t in; } bitlens; } length_block; length_block.bitlens.ad = ad_len * 8; length_block.bitlens.in = in_len * 8; aesgcmsiv_polyval_horner(out_tag, auth_key, length_block.c, 1); for (size_t i = 0; i < 12; i++) { out_tag[i] ^= nonce[i]; } out_tag[15] &= 0x7f; } // aead_aes_gcm_siv_asm_crypt_last_block handles the encryption/decryption // (same thing in CTR mode) of the final block of a plaintext/ciphertext. It // writes |in_len| & 15 bytes to |out| + |in_len|, based on an initial counter // derived from |tag|. static void aead_aes_gcm_siv_asm_crypt_last_block( int is_128_bit, uint8_t *out, const uint8_t *in, size_t in_len, const uint8_t tag[16], const struct aead_aes_gcm_siv_asm_ctx *enc_key_expanded) { alignas(16) union { uint8_t c[16]; uint32_t u32[4]; } counter; OPENSSL_memcpy(&counter, tag, sizeof(counter)); counter.c[15] |= 0x80; counter.u32[0] += in_len / 16; if (is_128_bit) { aes128gcmsiv_ecb_enc_block(&counter.c[0], &counter.c[0], enc_key_expanded); } else { aes256gcmsiv_ecb_enc_block(&counter.c[0], &counter.c[0], enc_key_expanded); } const size_t last_bytes_offset = in_len & ~15; const size_t last_bytes_len = in_len & 15; uint8_t *last_bytes_out = &out[last_bytes_offset]; const uint8_t *last_bytes_in = &in[last_bytes_offset]; for (size_t i = 0; i < last_bytes_len; i++) { last_bytes_out[i] = last_bytes_in[i] ^ counter.c[i]; } } // aead_aes_gcm_siv_kdf calculates the record encryption and authentication // keys given the |nonce|. static void aead_aes_gcm_siv_kdf( int is_128_bit, const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx, uint64_t out_record_auth_key[2], uint64_t out_record_enc_key[4], const uint8_t nonce[12]) { alignas(16) uint8_t padded_nonce[16]; OPENSSL_memcpy(padded_nonce, nonce, 12); alignas(16) uint64_t key_material[12]; if (is_128_bit) { aes128gcmsiv_kdf(padded_nonce, key_material, &gcm_siv_ctx->key[0]); out_record_enc_key[0] = key_material[4]; out_record_enc_key[1] = key_material[6]; } else { aes256gcmsiv_kdf(padded_nonce, key_material, &gcm_siv_ctx->key[0]); out_record_enc_key[0] = key_material[4]; out_record_enc_key[1] = key_material[6]; out_record_enc_key[2] = key_material[8]; out_record_enc_key[3] = key_material[10]; } out_record_auth_key[0] = key_material[0]; out_record_auth_key[1] = key_material[2]; } static int aead_aes_gcm_siv_asm_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_gcm_siv_asm_ctx *gcm_siv_ctx = asm_ctx_from_ctx(ctx); const uint64_t in_len_64 = in_len; const uint64_t ad_len_64 = ad_len; if (in_len_64 > (UINT64_C(1) << 36) || ad_len_64 >= (UINT64_C(1) << 61)) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); return 0; } if (max_out_tag_len < EVP_AEAD_AES_GCM_SIV_TAG_LEN) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL); return 0; } if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); return 0; } alignas(16) uint64_t record_auth_key[2]; alignas(16) uint64_t record_enc_key[4]; aead_aes_gcm_siv_kdf(gcm_siv_ctx->is_128_bit, gcm_siv_ctx, record_auth_key, record_enc_key, nonce); alignas(16) uint8_t tag[16] = {0}; gcm_siv_asm_polyval(tag, in, in_len, ad, ad_len, (const uint8_t *)record_auth_key, nonce); struct aead_aes_gcm_siv_asm_ctx enc_key_expanded; if (gcm_siv_ctx->is_128_bit) { aes128gcmsiv_aes_ks_enc_x1(tag, tag, &enc_key_expanded.key[0], record_enc_key); if (in_len < 128) { aes128gcmsiv_enc_msg_x4(in, out, tag, &enc_key_expanded, in_len & ~15); } else { aes128gcmsiv_enc_msg_x8(in, out, tag, &enc_key_expanded, in_len & ~15); } } else { aes256gcmsiv_aes_ks_enc_x1(tag, tag, &enc_key_expanded.key[0], record_enc_key); if (in_len < 128) { aes256gcmsiv_enc_msg_x4(in, out, tag, &enc_key_expanded, in_len & ~15); } else { aes256gcmsiv_enc_msg_x8(in, out, tag, &enc_key_expanded, in_len & ~15); } } if (in_len & 15) { aead_aes_gcm_siv_asm_crypt_last_block(gcm_siv_ctx->is_128_bit, out, in, in_len, tag, &enc_key_expanded); } OPENSSL_memcpy(out_tag, tag, sizeof(tag)); *out_tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN; return 1; } // TODO(martinkr): Add aead_aes_gcm_siv_asm_open_gather. N.B. aes128gcmsiv_dec // expects ciphertext and tag in a contiguous buffer. static int aead_aes_gcm_siv_asm_open(const EVP_AEAD_CTX *ctx, uint8_t *out, size_t *out_len, size_t max_out_len, const uint8_t *nonce, size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *ad, size_t ad_len) { const uint64_t ad_len_64 = ad_len; if (ad_len_64 >= (UINT64_C(1) << 61)) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); return 0; } const uint64_t in_len_64 = in_len; if (in_len < EVP_AEAD_AES_GCM_SIV_TAG_LEN || in_len_64 > (UINT64_C(1) << 36) + AES_BLOCK_SIZE) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); return 0; } if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); return 0; } const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx = asm_ctx_from_ctx(ctx); const size_t plaintext_len = in_len - EVP_AEAD_AES_GCM_SIV_TAG_LEN; const uint8_t *const given_tag = in + plaintext_len; if (max_out_len < plaintext_len) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL); return 0; } alignas(16) uint64_t record_auth_key[2]; alignas(16) uint64_t record_enc_key[4]; aead_aes_gcm_siv_kdf(gcm_siv_ctx->is_128_bit, gcm_siv_ctx, record_auth_key, record_enc_key, nonce); struct aead_aes_gcm_siv_asm_ctx expanded_key; if (gcm_siv_ctx->is_128_bit) { aes128gcmsiv_aes_ks((const uint8_t *) record_enc_key, &expanded_key.key[0]); } else { aes256gcmsiv_aes_ks((const uint8_t *) record_enc_key, &expanded_key.key[0]); } // calculated_tag is 16*8 bytes, rather than 16 bytes, because // aes[128|256]gcmsiv_dec uses the extra as scratch space. alignas(16) uint8_t calculated_tag[16 * 8] = {0}; OPENSSL_memset(calculated_tag, 0, EVP_AEAD_AES_GCM_SIV_TAG_LEN); const size_t ad_blocks = ad_len / 16; aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key, ad, ad_blocks); uint8_t scratch[16]; if (ad_len & 15) { OPENSSL_memset(scratch, 0, sizeof(scratch)); OPENSSL_memcpy(scratch, &ad[ad_len & ~15], ad_len & 15); aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key, scratch, 1); } alignas(16) uint8_t htable[16 * 6]; aesgcmsiv_htable6_init(htable, (const uint8_t *)record_auth_key); if (gcm_siv_ctx->is_128_bit) { aes128gcmsiv_dec(in, out, calculated_tag, htable, &expanded_key, plaintext_len); } else { aes256gcmsiv_dec(in, out, calculated_tag, htable, &expanded_key, plaintext_len); } if (plaintext_len & 15) { aead_aes_gcm_siv_asm_crypt_last_block(gcm_siv_ctx->is_128_bit, out, in, plaintext_len, given_tag, &expanded_key); OPENSSL_memset(scratch, 0, sizeof(scratch)); OPENSSL_memcpy(scratch, out + (plaintext_len & ~15), plaintext_len & 15); aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key, scratch, 1); } union { uint8_t c[16]; struct { uint64_t ad; uint64_t in; } bitlens; } length_block; length_block.bitlens.ad = ad_len * 8; length_block.bitlens.in = plaintext_len * 8; aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key, length_block.c, 1); for (size_t i = 0; i < 12; i++) { calculated_tag[i] ^= nonce[i]; } calculated_tag[15] &= 0x7f; if (gcm_siv_ctx->is_128_bit) { aes128gcmsiv_ecb_enc_block(calculated_tag, calculated_tag, &expanded_key); } else { aes256gcmsiv_ecb_enc_block(calculated_tag, calculated_tag, &expanded_key); } if (CRYPTO_memcmp(calculated_tag, given_tag, EVP_AEAD_AES_GCM_SIV_TAG_LEN) != 0) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); return 0; } *out_len = in_len - EVP_AEAD_AES_GCM_SIV_TAG_LEN; return 1; } static const EVP_AEAD aead_aes_128_gcm_siv_asm = { 16, // key length EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length 0, // seal_scatter_supports_extra_in aead_aes_gcm_siv_asm_init, NULL /* init_with_direction */, aead_aes_gcm_siv_asm_cleanup, aead_aes_gcm_siv_asm_open, aead_aes_gcm_siv_asm_seal_scatter, NULL /* open_gather */, NULL /* get_iv */, NULL /* tag_len */, }; static const EVP_AEAD aead_aes_256_gcm_siv_asm = { 32, // key length EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length 0, // seal_scatter_supports_extra_in aead_aes_gcm_siv_asm_init, NULL /* init_with_direction */, aead_aes_gcm_siv_asm_cleanup, aead_aes_gcm_siv_asm_open, aead_aes_gcm_siv_asm_seal_scatter, NULL /* open_gather */, NULL /* get_iv */, NULL /* tag_len */, }; #endif // X86_64 && !NO_ASM && !WINDOWS struct aead_aes_gcm_siv_ctx { union { double align; AES_KEY ks; } ks; block128_f kgk_block; unsigned is_256:1; }; OPENSSL_STATIC_ASSERT(sizeof(((EVP_AEAD_CTX *)NULL)->state) >= sizeof(struct aead_aes_gcm_siv_ctx), "AEAD state is too small"); #if defined(__GNUC__) || defined(__clang__) OPENSSL_STATIC_ASSERT(alignof(union evp_aead_ctx_st_state) >= alignof(struct aead_aes_gcm_siv_ctx), "AEAD state has insufficient alignment"); #endif static int aead_aes_gcm_siv_init(EVP_AEAD_CTX *ctx, const uint8_t *key, size_t key_len, size_t tag_len) { const size_t key_bits = key_len * 8; if (key_bits != 128 && key_bits != 256) { 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_GCM_SIV_TAG_LEN; } if (tag_len != EVP_AEAD_AES_GCM_SIV_TAG_LEN) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TAG_TOO_LARGE); return 0; } struct aead_aes_gcm_siv_ctx *gcm_siv_ctx = (struct aead_aes_gcm_siv_ctx *)&ctx->state; OPENSSL_memset(gcm_siv_ctx, 0, sizeof(struct aead_aes_gcm_siv_ctx)); aes_ctr_set_key(&gcm_siv_ctx->ks.ks, NULL, &gcm_siv_ctx->kgk_block, key, key_len); gcm_siv_ctx->is_256 = (key_len == 32); ctx->tag_len = tag_len; return 1; } static void aead_aes_gcm_siv_cleanup(EVP_AEAD_CTX *ctx) {} // gcm_siv_crypt encrypts (or decrypts—it's the same thing) |in_len| bytes from // |in| to |out|, using the block function |enc_block| with |key| in counter // mode, starting at |initial_counter|. This differs from the traditional // counter mode code in that the counter is handled little-endian, only the // first four bytes are used and the GCM-SIV tweak to the final byte is // applied. The |in| and |out| pointers may be equal but otherwise must not // alias. static void gcm_siv_crypt(uint8_t *out, const uint8_t *in, size_t in_len, const uint8_t initial_counter[AES_BLOCK_SIZE], block128_f enc_block, const AES_KEY *key) { union { uint32_t w[4]; uint8_t c[16]; } counter; OPENSSL_memcpy(counter.c, initial_counter, AES_BLOCK_SIZE); counter.c[15] |= 0x80; for (size_t done = 0; done < in_len;) { uint8_t keystream[AES_BLOCK_SIZE]; enc_block(counter.c, keystream, key); counter.w[0]++; size_t todo = AES_BLOCK_SIZE; if (in_len - done < todo) { todo = in_len - done; } for (size_t i = 0; i < todo; i++) { out[done + i] = keystream[i] ^ in[done + i]; } done += todo; } } // gcm_siv_polyval evaluates POLYVAL at |auth_key| on the given plaintext and // AD. The result is written to |out_tag|. static void gcm_siv_polyval( uint8_t out_tag[16], const uint8_t *in, size_t in_len, const uint8_t *ad, size_t ad_len, const uint8_t auth_key[16], const uint8_t nonce[EVP_AEAD_AES_GCM_SIV_NONCE_LEN]) { struct polyval_ctx polyval_ctx; CRYPTO_POLYVAL_init(&polyval_ctx, auth_key); CRYPTO_POLYVAL_update_blocks(&polyval_ctx, ad, ad_len & ~15); uint8_t scratch[16]; if (ad_len & 15) { OPENSSL_memset(scratch, 0, sizeof(scratch)); OPENSSL_memcpy(scratch, &ad[ad_len & ~15], ad_len & 15); CRYPTO_POLYVAL_update_blocks(&polyval_ctx, scratch, sizeof(scratch)); } CRYPTO_POLYVAL_update_blocks(&polyval_ctx, in, in_len & ~15); if (in_len & 15) { OPENSSL_memset(scratch, 0, sizeof(scratch)); OPENSSL_memcpy(scratch, &in[in_len & ~15], in_len & 15); CRYPTO_POLYVAL_update_blocks(&polyval_ctx, scratch, sizeof(scratch)); } union { uint8_t c[16]; struct { uint64_t ad; uint64_t in; } bitlens; } length_block; length_block.bitlens.ad = ad_len * 8; length_block.bitlens.in = in_len * 8; CRYPTO_POLYVAL_update_blocks(&polyval_ctx, length_block.c, sizeof(length_block)); CRYPTO_POLYVAL_finish(&polyval_ctx, out_tag); for (size_t i = 0; i < EVP_AEAD_AES_GCM_SIV_NONCE_LEN; i++) { out_tag[i] ^= nonce[i]; } out_tag[15] &= 0x7f; } // gcm_siv_record_keys contains the keys used for a specific GCM-SIV record. struct gcm_siv_record_keys { uint8_t auth_key[16]; union { double align; AES_KEY ks; } enc_key; block128_f enc_block; }; // gcm_siv_keys calculates the keys for a specific GCM-SIV record with the // given nonce and writes them to |*out_keys|. static void gcm_siv_keys( const struct aead_aes_gcm_siv_ctx *gcm_siv_ctx, struct gcm_siv_record_keys *out_keys, const uint8_t nonce[EVP_AEAD_AES_GCM_SIV_NONCE_LEN]) { const AES_KEY *const key = &gcm_siv_ctx->ks.ks; uint8_t key_material[(128 /* POLYVAL key */ + 256 /* max AES key */) / 8]; const size_t blocks_needed = gcm_siv_ctx->is_256 ? 6 : 4; uint8_t counter[AES_BLOCK_SIZE]; OPENSSL_memset(counter, 0, AES_BLOCK_SIZE - EVP_AEAD_AES_GCM_SIV_NONCE_LEN); OPENSSL_memcpy(counter + AES_BLOCK_SIZE - EVP_AEAD_AES_GCM_SIV_NONCE_LEN, nonce, EVP_AEAD_AES_GCM_SIV_NONCE_LEN); for (size_t i = 0; i < blocks_needed; i++) { counter[0] = i; uint8_t ciphertext[AES_BLOCK_SIZE]; gcm_siv_ctx->kgk_block(counter, ciphertext, key); OPENSSL_memcpy(&key_material[i * 8], ciphertext, 8); } OPENSSL_memcpy(out_keys->auth_key, key_material, 16); // Note the |ctr128_f| function uses a big-endian couner, while AES-GCM-SIV // uses a little-endian counter. We ignore the return value and only use // |block128_f|. This has a significant performance cost for the fallback // bitsliced AES implementations (bsaes and aes_nohw). // // We currently do not consider AES-GCM-SIV to be performance-sensitive on // client hardware. If this changes, we can write little-endian |ctr128_f| // functions. aes_ctr_set_key(&out_keys->enc_key.ks, NULL, &out_keys->enc_block, key_material + 16, gcm_siv_ctx->is_256 ? 32 : 16); } static int aead_aes_gcm_siv_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_gcm_siv_ctx *gcm_siv_ctx = (struct aead_aes_gcm_siv_ctx *)&ctx->state; const uint64_t in_len_64 = in_len; const uint64_t ad_len_64 = ad_len; if (in_len + EVP_AEAD_AES_GCM_SIV_TAG_LEN < in_len || in_len_64 > (UINT64_C(1) << 36) || ad_len_64 >= (UINT64_C(1) << 61)) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); return 0; } if (max_out_tag_len < EVP_AEAD_AES_GCM_SIV_TAG_LEN) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL); return 0; } if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); return 0; } struct gcm_siv_record_keys keys; gcm_siv_keys(gcm_siv_ctx, &keys, nonce); uint8_t tag[16]; gcm_siv_polyval(tag, in, in_len, ad, ad_len, keys.auth_key, nonce); keys.enc_block(tag, tag, &keys.enc_key.ks); gcm_siv_crypt(out, in, in_len, tag, keys.enc_block, &keys.enc_key.ks); OPENSSL_memcpy(out_tag, tag, EVP_AEAD_AES_GCM_SIV_TAG_LEN); *out_tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN; return 1; } static int aead_aes_gcm_siv_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 uint64_t ad_len_64 = ad_len; if (ad_len_64 >= (UINT64_C(1) << 61)) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); return 0; } const uint64_t in_len_64 = in_len; if (in_tag_len != EVP_AEAD_AES_GCM_SIV_TAG_LEN || in_len_64 > (UINT64_C(1) << 36) + AES_BLOCK_SIZE) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); return 0; } if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); return 0; } const struct aead_aes_gcm_siv_ctx *gcm_siv_ctx = (struct aead_aes_gcm_siv_ctx *)&ctx->state; struct gcm_siv_record_keys keys; gcm_siv_keys(gcm_siv_ctx, &keys, nonce); gcm_siv_crypt(out, in, in_len, in_tag, keys.enc_block, &keys.enc_key.ks); uint8_t expected_tag[EVP_AEAD_AES_GCM_SIV_TAG_LEN]; gcm_siv_polyval(expected_tag, out, in_len, ad, ad_len, keys.auth_key, nonce); keys.enc_block(expected_tag, expected_tag, &keys.enc_key.ks); if (CRYPTO_memcmp(expected_tag, in_tag, sizeof(expected_tag)) != 0) { OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); return 0; } return 1; } static const EVP_AEAD aead_aes_128_gcm_siv = { 16, // key length EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length 0, // seal_scatter_supports_extra_in aead_aes_gcm_siv_init, NULL /* init_with_direction */, aead_aes_gcm_siv_cleanup, NULL /* open */, aead_aes_gcm_siv_seal_scatter, aead_aes_gcm_siv_open_gather, NULL /* get_iv */, NULL /* tag_len */, }; static const EVP_AEAD aead_aes_256_gcm_siv = { 32, // key length EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length 0, // seal_scatter_supports_extra_in aead_aes_gcm_siv_init, NULL /* init_with_direction */, aead_aes_gcm_siv_cleanup, NULL /* open */, aead_aes_gcm_siv_seal_scatter, aead_aes_gcm_siv_open_gather, NULL /* get_iv */, NULL /* tag_len */, }; #if defined(AES_GCM_SIV_ASM) static char avx_aesni_capable(void) { const uint32_t ecx = OPENSSL_ia32cap_P[1]; return (ecx & (1 << (57 - 32))) != 0 /* AESNI */ && (ecx & (1 << 28)) != 0 /* AVX */; } const EVP_AEAD *EVP_aead_aes_128_gcm_siv(void) { if (avx_aesni_capable()) { return &aead_aes_128_gcm_siv_asm; } return &aead_aes_128_gcm_siv; } const EVP_AEAD *EVP_aead_aes_256_gcm_siv(void) { if (avx_aesni_capable()) { return &aead_aes_256_gcm_siv_asm; } return &aead_aes_256_gcm_siv; } #else const EVP_AEAD *EVP_aead_aes_128_gcm_siv(void) { return &aead_aes_128_gcm_siv; } const EVP_AEAD *EVP_aead_aes_256_gcm_siv(void) { return &aead_aes_256_gcm_siv; } #endif // AES_GCM_SIV_ASM