From d9e397b599b13d642138480a28c14db7a136bf05 Mon Sep 17 00:00:00 2001 From: Adam Langley Date: Thu, 22 Jan 2015 14:27:53 -0800 Subject: Initial commit of BoringSSL for Android. --- src/crypto/cipher/e_chacha20poly1305.c | 218 +++++++++++++++++++++++++++++++++ 1 file changed, 218 insertions(+) create mode 100644 src/crypto/cipher/e_chacha20poly1305.c (limited to 'src/crypto/cipher/e_chacha20poly1305.c') diff --git a/src/crypto/cipher/e_chacha20poly1305.c b/src/crypto/cipher/e_chacha20poly1305.c new file mode 100644 index 0000000..1cdcbca --- /dev/null +++ b/src/crypto/cipher/e_chacha20poly1305.c @@ -0,0 +1,218 @@ +/* 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 + +#include + +#include +#include +#include +#include +#include + +#include "internal.h" + + +#define POLY1305_TAG_LEN 16 +#define CHACHA20_NONCE_LEN 8 + +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, aead_chacha20_poly1305_init, 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_with_length(poly1305_state *poly1305, + const uint8_t *data, size_t data_len) { + size_t j = data_len; + uint8_t length_bytes[8]; + unsigned i; + + for (i = 0; i < sizeof(length_bytes); i++) { + length_bytes[i] = j; + j >>= 8; + } + + CRYPTO_poly1305_update(poly1305, data, data_len); + CRYPTO_poly1305_update(poly1305, length_bytes, sizeof(length_bytes)); +} + +#if defined(__arm__) +#define ALIGNED __attribute__((aligned(16))) +#else +#define ALIGNED +#endif + +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) { + const struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state; + uint8_t poly1305_key[32] ALIGNED; + poly1305_state poly1305; + const uint64_t in_len_64 = in_len; + + /* The underlying ChaCha implementation may not overflow the block + * counter into the second counter word. 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, aead_chacha20_poly1305_seal, CIPHER_R_TOO_LARGE); + return 0; + } + + if (in_len + c20_ctx->tag_len < in_len) { + OPENSSL_PUT_ERROR(CIPHER, aead_chacha20_poly1305_seal, CIPHER_R_TOO_LARGE); + return 0; + } + + if (max_out_len < in_len + c20_ctx->tag_len) { + OPENSSL_PUT_ERROR(CIPHER, aead_chacha20_poly1305_seal, + CIPHER_R_BUFFER_TOO_SMALL); + return 0; + } + + if (nonce_len != CHACHA20_NONCE_LEN) { + OPENSSL_PUT_ERROR(CIPHER, aead_chacha20_poly1305_seal, CIPHER_R_IV_TOO_LARGE); + return 0; + } + + memset(poly1305_key, 0, sizeof(poly1305_key)); + CRYPTO_chacha_20(poly1305_key, poly1305_key, sizeof(poly1305_key), + c20_ctx->key, nonce, 0); + + CRYPTO_poly1305_init(&poly1305, poly1305_key); + poly1305_update_with_length(&poly1305, ad, ad_len); + CRYPTO_chacha_20(out, in, in_len, c20_ctx->key, nonce, 1); + poly1305_update_with_length(&poly1305, out, in_len); + + uint8_t tag[POLY1305_TAG_LEN] ALIGNED; + CRYPTO_poly1305_finish(&poly1305, tag); + memcpy(out + in_len, tag, c20_ctx->tag_len); + *out_len = in_len + c20_ctx->tag_len; + return 1; +} + +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) { + const struct aead_chacha20_poly1305_ctx *c20_ctx = ctx->aead_state; + uint8_t mac[POLY1305_TAG_LEN]; + uint8_t poly1305_key[32] ALIGNED; + size_t plaintext_len; + poly1305_state poly1305; + const uint64_t in_len_64 = in_len; + + if (in_len < c20_ctx->tag_len) { + OPENSSL_PUT_ERROR(CIPHER, aead_chacha20_poly1305_open, CIPHER_R_BAD_DECRYPT); + return 0; + } + + /* The underlying ChaCha implementation may not overflow the block + * counter into the second counter word. 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, aead_chacha20_poly1305_open, CIPHER_R_TOO_LARGE); + return 0; + } + + if (nonce_len != CHACHA20_NONCE_LEN) { + OPENSSL_PUT_ERROR(CIPHER, aead_chacha20_poly1305_open, CIPHER_R_IV_TOO_LARGE); + return 0; + } + + plaintext_len = in_len - c20_ctx->tag_len; + + if (max_out_len < plaintext_len) { + OPENSSL_PUT_ERROR(CIPHER, aead_chacha20_poly1305_open, + CIPHER_R_BUFFER_TOO_SMALL); + return 0; + } + + memset(poly1305_key, 0, sizeof(poly1305_key)); + CRYPTO_chacha_20(poly1305_key, poly1305_key, sizeof(poly1305_key), + c20_ctx->key, nonce, 0); + + CRYPTO_poly1305_init(&poly1305, poly1305_key); + poly1305_update_with_length(&poly1305, ad, ad_len); + poly1305_update_with_length(&poly1305, in, plaintext_len); + CRYPTO_poly1305_finish(&poly1305, mac); + + if (CRYPTO_memcmp(mac, in + plaintext_len, c20_ctx->tag_len) != 0) { + OPENSSL_PUT_ERROR(CIPHER, aead_chacha20_poly1305_open, 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 const EVP_AEAD aead_chacha20_poly1305 = { + 32, /* key len */ + CHACHA20_NONCE_LEN, /* nonce len */ + POLY1305_TAG_LEN, /* overhead */ + POLY1305_TAG_LEN, /* max tag length */ + aead_chacha20_poly1305_init, aead_chacha20_poly1305_cleanup, + aead_chacha20_poly1305_seal, aead_chacha20_poly1305_open, +}; + +const EVP_AEAD *EVP_aead_chacha20_poly1305(void) { + return &aead_chacha20_poly1305; +} -- cgit v1.1