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- /* 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"
-
-
- #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;
- }
-
- 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));
- }
-
- #if defined(__arm__)
- #define ALIGNED __attribute__((aligned(16)))
- #else
- #define ALIGNED
- #endif
-
- 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) {
- uint8_t poly1305_key[32] ALIGNED;
- 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 >= (1ull << 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);
-
- uint8_t tag[POLY1305_TAG_LEN] ALIGNED;
- aead_poly1305(poly1305_update, tag, c20_ctx, nonce, ad, ad_len, out, in_len);
-
- 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 >= (1ull << 32) * 64 - 64) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
- return 0;
- }
-
- plaintext_len = in_len - c20_ctx->tag_len;
- uint8_t tag[POLY1305_TAG_LEN] ALIGNED;
- 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_rc4_state */
- NULL, /* get_iv */
- };
-
- const EVP_AEAD *EVP_aead_chacha20_poly1305_rfc7539(void) {
- return &aead_chacha20_poly1305;
- }
-
- static void poly1305_update_old(poly1305_state *ctx, const uint8_t *ad,
- size_t ad_len, const uint8_t *ciphertext,
- size_t ciphertext_len) {
- CRYPTO_poly1305_update(ctx, ad, ad_len);
- poly1305_update_length(ctx, ad_len);
- CRYPTO_poly1305_update(ctx, ciphertext, ciphertext_len);
- poly1305_update_length(ctx, ciphertext_len);
- }
-
- static int aead_chacha20_poly1305_old_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 != 8) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
- return 0;
- }
- uint8_t nonce_96[12];
- memset(nonce_96, 0, 4);
- memcpy(nonce_96 + 4, nonce, 8);
- return seal_impl(poly1305_update_old, ctx, out, out_len, max_out_len,
- nonce_96, in, in_len, ad, ad_len);
- }
-
- static int aead_chacha20_poly1305_old_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 != 8) {
- OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
- return 0;
- }
- uint8_t nonce_96[12];
- memset(nonce_96, 0, 4);
- memcpy(nonce_96 + 4, nonce, 8);
- return open_impl(poly1305_update_old, ctx, out, out_len, max_out_len,
- nonce_96, in, in_len, ad, ad_len);
- }
-
- static const EVP_AEAD aead_chacha20_poly1305_old = {
- 32, /* key len */
- 8, /* 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_old_seal,
- aead_chacha20_poly1305_old_open,
- NULL, /* get_rc4_state */
- NULL, /* get_iv */
- };
-
- const EVP_AEAD *EVP_aead_chacha20_poly1305_old(void) {
- return &aead_chacha20_poly1305_old;
- }
-
- const EVP_AEAD *EVP_aead_chacha20_poly1305(void) {
- return &aead_chacha20_poly1305_old;
- }
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