| /* Copyright (c) 2014, 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 <string.h> |
| |
| #include <openssl/chacha.h> |
| #include <openssl/cipher.h> |
| #include <openssl/err.h> |
| #include <openssl/mem.h> |
| #include <openssl/poly1305.h> |
| |
| #include "internal.h" |
| #include "../internal.h" |
| |
| |
| #define POLY1305_TAG_LEN 16 |
| |
| struct aead_chacha20_poly1305_ctx { |
| unsigned char key[32]; |
| unsigned char tag_len; |
| }; |
| |
| static int aead_chacha20_poly1305_init(EVP_AEAD_CTX *ctx, const uint8_t *key, |
| size_t key_len, size_t tag_len) { |
| struct aead_chacha20_poly1305_ctx *c20_ctx; |
| |
| if (tag_len == 0) { |
| tag_len = POLY1305_TAG_LEN; |
| } |
| |
| if (tag_len > POLY1305_TAG_LEN) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); |
| return 0; |
| } |
| |
| if (key_len != sizeof(c20_ctx->key)) { |
| return 0; /* internal error - EVP_AEAD_CTX_init should catch this. */ |
| } |
| |
| c20_ctx = OPENSSL_malloc(sizeof(struct aead_chacha20_poly1305_ctx)); |
| if (c20_ctx == NULL) { |
| return 0; |
| } |
| |
| OPENSSL_memcpy(c20_ctx->key, key, key_len); |
| c20_ctx->tag_len = tag_len; |
| ctx->aead_state = c20_ctx; |
| |
| return 1; |
| } |
| |
| static void aead_chacha20_poly1305_cleanup(EVP_AEAD_CTX *ctx) { |
| struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state; |
| OPENSSL_cleanse(c20_ctx->key, sizeof(c20_ctx->key)); |
| OPENSSL_free(c20_ctx); |
| } |
| |
| static void poly1305_update_length(poly1305_state *poly1305, size_t data_len) { |
| uint8_t length_bytes[8]; |
| unsigned i; |
| |
| for (i = 0; i < sizeof(length_bytes); i++) { |
| length_bytes[i] = data_len; |
| data_len >>= 8; |
| } |
| |
| CRYPTO_poly1305_update(poly1305, length_bytes, sizeof(length_bytes)); |
| } |
| |
| typedef void (*aead_poly1305_update)(poly1305_state *ctx, const uint8_t *ad, |
| size_t ad_len, const uint8_t *ciphertext, |
| size_t ciphertext_len); |
| |
| /* aead_poly1305 fills |tag| with the authentication tag for the given |
| * inputs, using |update| to control the order and format that the inputs are |
| * signed/authenticated. */ |
| static void aead_poly1305(aead_poly1305_update update, |
| uint8_t tag[POLY1305_TAG_LEN], |
| const struct aead_chacha20_poly1305_ctx *c20_ctx, |
| const uint8_t nonce[12], const uint8_t *ad, |
| size_t ad_len, const uint8_t *ciphertext, |
| size_t ciphertext_len) { |
| alignas(16) uint8_t poly1305_key[32]; |
| OPENSSL_memset(poly1305_key, 0, sizeof(poly1305_key)); |
| CRYPTO_chacha_20(poly1305_key, poly1305_key, sizeof(poly1305_key), |
| c20_ctx->key, nonce, 0); |
| poly1305_state ctx; |
| CRYPTO_poly1305_init(&ctx, poly1305_key); |
| update(&ctx, ad, ad_len, ciphertext, ciphertext_len); |
| CRYPTO_poly1305_finish(&ctx, tag); |
| } |
| |
| static int seal_impl(aead_poly1305_update poly1305_update, |
| const EVP_AEAD_CTX *ctx, uint8_t *out, size_t *out_len, |
| size_t max_out_len, const uint8_t nonce[12], |
| const uint8_t *in, size_t in_len, const uint8_t *ad, |
| size_t ad_len) { |
| const struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state; |
| const uint64_t in_len_64 = in_len; |
| |
| /* |CRYPTO_chacha_20| uses a 32-bit block counter. Therefore we disallow |
| * individual operations that work on more than 256GB at a time. |
| * |in_len_64| is needed because, on 32-bit platforms, size_t is only |
| * 32-bits and this produces a warning because it's always false. |
| * Casting to uint64_t inside the conditional is not sufficient to stop |
| * the warning. */ |
| if (in_len_64 >= (UINT64_C(1) << 32) * 64 - 64) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); |
| return 0; |
| } |
| |
| if (in_len + c20_ctx->tag_len < in_len) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); |
| return 0; |
| } |
| |
| if (max_out_len < in_len + c20_ctx->tag_len) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL); |
| return 0; |
| } |
| |
| CRYPTO_chacha_20(out, in, in_len, c20_ctx->key, nonce, 1); |
| |
| alignas(16) uint8_t tag[POLY1305_TAG_LEN]; |
| aead_poly1305(poly1305_update, tag, c20_ctx, nonce, ad, ad_len, out, in_len); |
| |
| OPENSSL_memcpy(out + in_len, tag, c20_ctx->tag_len); |
| *out_len = in_len + c20_ctx->tag_len; |
| return 1; |
| } |
| |
| static int open_impl(aead_poly1305_update poly1305_update, |
| const EVP_AEAD_CTX *ctx, uint8_t *out, size_t *out_len, |
| size_t max_out_len, const uint8_t nonce[12], |
| const uint8_t *in, size_t in_len, const uint8_t *ad, |
| size_t ad_len) { |
| const struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state; |
| size_t plaintext_len; |
| const uint64_t in_len_64 = in_len; |
| |
| if (in_len < c20_ctx->tag_len) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); |
| return 0; |
| } |
| |
| /* |CRYPTO_chacha_20| uses a 32-bit block counter. Therefore we disallow |
| * individual operations that work on more than 256GB at a time. |
| * |in_len_64| is needed because, on 32-bit platforms, size_t is only |
| * 32-bits and this produces a warning because it's always false. |
| * Casting to uint64_t inside the conditional is not sufficient to stop |
| * the warning. */ |
| if (in_len_64 >= (UINT64_C(1) << 32) * 64 - 64) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE); |
| return 0; |
| } |
| |
| plaintext_len = in_len - c20_ctx->tag_len; |
| alignas(16) uint8_t tag[POLY1305_TAG_LEN]; |
| aead_poly1305(poly1305_update, tag, c20_ctx, nonce, ad, ad_len, in, |
| plaintext_len); |
| if (CRYPTO_memcmp(tag, in + plaintext_len, c20_ctx->tag_len) != 0) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT); |
| return 0; |
| } |
| |
| CRYPTO_chacha_20(out, in, plaintext_len, c20_ctx->key, nonce, 1); |
| *out_len = plaintext_len; |
| return 1; |
| } |
| |
| static void poly1305_update_padded_16(poly1305_state *poly1305, |
| const uint8_t *data, size_t data_len) { |
| static const uint8_t padding[16] = { 0 }; /* Padding is all zeros. */ |
| |
| CRYPTO_poly1305_update(poly1305, data, data_len); |
| if (data_len % 16 != 0) { |
| CRYPTO_poly1305_update(poly1305, padding, sizeof(padding) - (data_len % 16)); |
| } |
| } |
| |
| static void poly1305_update(poly1305_state *ctx, const uint8_t *ad, |
| size_t ad_len, const uint8_t *ciphertext, |
| size_t ciphertext_len) { |
| poly1305_update_padded_16(ctx, ad, ad_len); |
| poly1305_update_padded_16(ctx, ciphertext, ciphertext_len); |
| poly1305_update_length(ctx, ad_len); |
| poly1305_update_length(ctx, ciphertext_len); |
| } |
| |
| static int aead_chacha20_poly1305_seal(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) { |
| if (nonce_len != 12) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); |
| return 0; |
| } |
| return seal_impl(poly1305_update, ctx, out, out_len, max_out_len, nonce, in, |
| in_len, ad, ad_len); |
| } |
| |
| static int aead_chacha20_poly1305_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) { |
| if (nonce_len != 12) { |
| OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE); |
| return 0; |
| } |
| return open_impl(poly1305_update, ctx, out, out_len, max_out_len, nonce, in, |
| in_len, ad, ad_len); |
| } |
| |
| static const EVP_AEAD aead_chacha20_poly1305 = { |
| 32, /* key len */ |
| 12, /* nonce len */ |
| POLY1305_TAG_LEN, /* overhead */ |
| POLY1305_TAG_LEN, /* max tag length */ |
| aead_chacha20_poly1305_init, |
| NULL, /* init_with_direction */ |
| aead_chacha20_poly1305_cleanup, |
| aead_chacha20_poly1305_seal, |
| aead_chacha20_poly1305_open, |
| NULL, /* get_iv */ |
| }; |
| |
| const EVP_AEAD *EVP_aead_chacha20_poly1305(void) { |
| return &aead_chacha20_poly1305; |
| } |