23721e3705
There's no good reason to do this, and it doesn't work; HMAC checks the length of the key and runs it through the hash function if too long. The reuse occurs after this check. This allows us to shave 132 bytes off HMAC_CTX as this was the only reason it ever stored the original key. It also slightly simplifies HMAC_Init_ex's logic. Change-Id: Ib56aabc3630b7178f1ee7c38ef6370c9638efbab Reviewed-on: https://boringssl-review.googlesource.com/3733 Reviewed-by: Adam Langley <agl@google.com>
168 lines
7.1 KiB
C
168 lines
7.1 KiB
C
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.] */
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#ifndef OPENSSL_HEADER_HMAC_H
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#define OPENSSL_HEADER_HMAC_H
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#include <openssl/base.h>
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#include <openssl/digest.h>
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#if defined(__cplusplus)
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extern "C" {
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#endif
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/* HMAC contains functions for constructing PRFs from Merkle–Damgård hash
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* functions using HMAC. */
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/* One-shot operation. */
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/* HMAC calculates the HMAC of |data_len| bytes of |data|, using the given key
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* and hash function, and writes the result to |out|. On entry, |out| must
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* contain |EVP_MAX_MD_SIZE| bytes of space. The actual length of the result is
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* written to |*out_len|. It returns |out| or NULL on error. */
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OPENSSL_EXPORT uint8_t *HMAC(const EVP_MD *evp_md, const void *key,
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size_t key_len, const uint8_t *data,
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size_t data_len, uint8_t *out,
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unsigned int *out_len);
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/* Incremental operation. */
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/* HMAC_CTX_init initialises |ctx| for use in an HMAC operation. It's assumed
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* that HMAC_CTX objects will be allocated on the stack thus no allocation
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* function is provided. If needed, allocate |sizeof(HMAC_CTX)| and call
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* |HMAC_CTX_init| on it. */
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OPENSSL_EXPORT void HMAC_CTX_init(HMAC_CTX *ctx);
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/* HMAC_CTX_cleanup frees data owned by |ctx|. */
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OPENSSL_EXPORT void HMAC_CTX_cleanup(HMAC_CTX *ctx);
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/* HMAC_Init_ex sets up an initialised |HMAC_CTX| to use |md| as the hash
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* function and |key| as the key. For a non-initial call, |md| may be NULL, in
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* which case the previous hash function will be used. If the hash function has
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* not changed and |key| is NULL, |ctx| reuses the previous key. It returns one
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* on success or zero otherwise.
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*
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* WARNING: NULL and empty keys are ambiguous on non-initial calls. Passing NULL
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* |key| but repeating the previous |md| reuses the previous key rather than the
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* empty key. */
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OPENSSL_EXPORT int HMAC_Init_ex(HMAC_CTX *ctx, const void *key, size_t key_len,
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const EVP_MD *md, ENGINE *impl);
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/* HMAC_Update hashes |data_len| bytes from |data| into the current HMAC
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* operation in |ctx|. It returns one on success and zero on error. */
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OPENSSL_EXPORT int HMAC_Update(HMAC_CTX *ctx, const uint8_t *data,
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size_t data_len);
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/* HMAC_Final completes the HMAC operation in |ctx| and writes the result to
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* |out| and the sets |*out_len| to the length of the result. On entry, |out|
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* must contain at least |EVP_MAX_MD_SIZE| bytes of space. It returns one on
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* success or zero on error. */
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OPENSSL_EXPORT int HMAC_Final(HMAC_CTX *ctx, uint8_t *out,
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unsigned int *out_len);
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/* Utility functions. */
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/* HMAC_size returns the size, in bytes, of the HMAC that will be produced by
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* |ctx|. On entry, |ctx| must have been setup with |HMAC_Init_ex|. */
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OPENSSL_EXPORT size_t HMAC_size(const HMAC_CTX *ctx);
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/* HMAC_CTX_copy_ex sets |dest| equal to |src|. On entry, |dest| must have been
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* initialised by calling |HMAC_CTX_init|. It returns one on success and zero
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* on error. */
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OPENSSL_EXPORT int HMAC_CTX_copy_ex(HMAC_CTX *dest, const HMAC_CTX *src);
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/* HMAC_CTX_set_flags ORs |flags| into the flags of the underlying digests of
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* |ctx|, which must have been setup by a call to |HMAC_Init_ex|. See
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* |EVP_MD_CTX_set_flags|.
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*
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* TODO(fork): remove? */
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OPENSSL_EXPORT void HMAC_CTX_set_flags(HMAC_CTX *ctx, unsigned long flags);
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/* Deprecated functions. */
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OPENSSL_EXPORT int HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len,
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const EVP_MD *md);
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/* HMAC_CTX_copy calls |HMAC_CTX_init| on |dest| and then sets it equal to
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* |src|. On entry, |dest| must /not/ be initialised for an operation with
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* |HMAC_Init_ex|. It returns one on success and zero on error. */
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OPENSSL_EXPORT int HMAC_CTX_copy(HMAC_CTX *dest, const HMAC_CTX *src);
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/* Private functions */
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#define HMAC_MAX_MD_CBLOCK 128 /* largest known is SHA512 */
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struct hmac_ctx_st {
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const EVP_MD *md;
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EVP_MD_CTX md_ctx;
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EVP_MD_CTX i_ctx;
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EVP_MD_CTX o_ctx;
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} /* HMAC_CTX */;
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#if defined(__cplusplus)
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} /* extern C */
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#endif
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#endif /* OPENSSL_HEADER_HMAC_H */
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