crypto/cipher/e_chacha20poly1305.c - boringssl - Git at Google

 /* 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 <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
 #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 __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);

   if (c20_ctx->tag_len != POLY1305_TAG_LEN) {
     uint8_t tag[POLY1305_TAG_LEN];
     CRYPTO_poly1305_finish(&poly1305, tag);
     memcpy(out + in_len, tag, c20_ctx->tag_len);
     *out_len = in_len + c20_ctx->tag_len;
     return 1;
   }

   CRYPTO_poly1305_finish(&poly1305, out + in_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;
 }
	/* 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 <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
	#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 __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);

	if (c20_ctx->tag_len != POLY1305_TAG_LEN) {
	uint8_t tag[POLY1305_TAG_LEN];
	CRYPTO_poly1305_finish(&poly1305, tag);
	memcpy(out + in_len, tag, c20_ctx->tag_len);
	*out_len = in_len + c20_ctx->tag_len;
	return 1;
	}

	CRYPTO_poly1305_finish(&poly1305, out + in_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;
	}