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/* $OpenBSD: evp_aead.c,v 1.6 2017/01/29 17:49:23 beck Exp $ */
/*
* 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 <limits.h>
#include <string.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include "evp_locl.h"
size_t
EVP_AEAD_key_length(const EVP_AEAD *aead)
{
return aead->key_len;
}
size_t
EVP_AEAD_nonce_length(const EVP_AEAD *aead)
{
return aead->nonce_len;
}
size_t
EVP_AEAD_max_overhead(const EVP_AEAD *aead)
{
return aead->overhead;
}
size_t
EVP_AEAD_max_tag_len(const EVP_AEAD *aead)
{
return aead->max_tag_len;
}
int
EVP_AEAD_CTX_init(EVP_AEAD_CTX *ctx, const EVP_AEAD *aead,
const unsigned char *key, size_t key_len, size_t tag_len, ENGINE *impl)
{
ctx->aead = aead;
if (key_len != aead->key_len) {
EVPerror(EVP_R_UNSUPPORTED_KEY_SIZE);
return 0;
}
return aead->init(ctx, key, key_len, tag_len);
}
void
EVP_AEAD_CTX_cleanup(EVP_AEAD_CTX *ctx)
{
if (ctx->aead == NULL)
return;
ctx->aead->cleanup(ctx);
ctx->aead = NULL;
}
/* check_alias returns 0 if out points within the buffer determined by in
* and in_len and 1 otherwise.
*
* When processing, there's only an issue if out points within in[:in_len]
* and isn't equal to in. If that's the case then writing the output will
* stomp input that hasn't been read yet.
*
* This function checks for that case. */
static int
check_alias(const unsigned char *in, size_t in_len, const unsigned char *out)
{
if (out <= in)
return 1;
if (in + in_len <= out)
return 1;
return 0;
}
int
EVP_AEAD_CTX_seal(const EVP_AEAD_CTX *ctx, unsigned char *out, size_t *out_len,
size_t max_out_len, const unsigned char *nonce, size_t nonce_len,
const unsigned char *in, size_t in_len, const unsigned char *ad,
size_t ad_len)
{
size_t possible_out_len = in_len + ctx->aead->overhead;
/* Overflow. */
if (possible_out_len < in_len) {
EVPerror(EVP_R_TOO_LARGE);
goto error;
}
if (!check_alias(in, in_len, out)) {
EVPerror(EVP_R_OUTPUT_ALIASES_INPUT);
goto error;
}
if (ctx->aead->seal(ctx, out, out_len, max_out_len, nonce, nonce_len,
in, in_len, ad, ad_len)) {
return 1;
}
error:
/* In the event of an error, clear the output buffer so that a caller
* that doesn't check the return value doesn't send raw data. */
memset(out, 0, max_out_len);
*out_len = 0;
return 0;
}
int
EVP_AEAD_CTX_open(const EVP_AEAD_CTX *ctx, unsigned char *out, size_t *out_len,
size_t max_out_len, const unsigned char *nonce, size_t nonce_len,
const unsigned char *in, size_t in_len, const unsigned char *ad,
size_t ad_len)
{
if (!check_alias(in, in_len, out)) {
EVPerror(EVP_R_OUTPUT_ALIASES_INPUT);
goto error;
}
if (ctx->aead->open(ctx, out, out_len, max_out_len, nonce, nonce_len,
in, in_len, ad, ad_len)) {
return 1;
}
error:
/* In the event of an error, clear the output buffer so that a caller
* that doesn't check the return value doesn't try and process bad
* data. */
memset(out, 0, max_out_len);
*out_len = 0;
return 0;
}
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