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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* lib/crypto/openssl/hmac.c */
/*
* Copyright (C) 2009 by the Massachusetts Institute of Technology.
* All rights reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
/*
* Copyright (C) 1998 by the FundsXpress, INC.
*
* All rights reserved.
*
* Export of this software from the United States of America may require
* a specific license from the United States Government. It is the
* responsibility of any person or organization contemplating export to
* obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of FundsXpress. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. FundsXpress makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include "crypto_int.h"
#include <openssl/hmac.h>
#include <openssl/evp.h>
/*
* the HMAC transform looks like:
*
* H(K XOR opad, H(K XOR ipad, text))
*
* where H is a cryptographic hash
* K is an n byte key
* ipad is the byte 0x36 repeated blocksize times
* opad is the byte 0x5c repeated blocksize times
* and text is the data being protected
*/
static const EVP_MD *
map_digest(const struct krb5_hash_provider *hash)
{
if (!strncmp(hash->hash_name, "SHA1",4))
return EVP_sha1();
else if (!strncmp(hash->hash_name, "MD5", 3))
return EVP_md5();
else if (!strncmp(hash->hash_name, "MD4", 3))
return EVP_md4();
else
return NULL;
}
krb5_error_code
krb5int_hmac_keyblock(const struct krb5_hash_provider *hash,
const krb5_keyblock *keyblock,
const krb5_crypto_iov *data, size_t num_data,
krb5_data *output)
{
unsigned int i = 0, md_len = 0;
unsigned char md[EVP_MAX_MD_SIZE];
HMAC_CTX c;
size_t hashsize, blocksize;
hashsize = hash->hashsize;
blocksize = hash->blocksize;
if (keyblock->length > blocksize)
return(KRB5_CRYPTO_INTERNAL);
if (output->length < hashsize)
return(KRB5_BAD_MSIZE);
if (!map_digest(hash))
return(KRB5_CRYPTO_INTERNAL); // unsupported alg
HMAC_CTX_init(&c);
HMAC_Init(&c, keyblock->contents, keyblock->length, map_digest(hash));
for (i = 0; i < num_data; i++) {
const krb5_crypto_iov *iov = &data[i];
if (SIGN_IOV(iov))
HMAC_Update(&c, (unsigned char*) iov->data.data, iov->data.length);
}
HMAC_Final(&c,(unsigned char *)md, &md_len);
if ( md_len <= output->length) {
output->length = md_len;
memcpy(output->data, md, output->length);
}
HMAC_CTX_cleanup(&c);
return 0;
}
krb5_error_code
krb5int_hmac(const struct krb5_hash_provider *hash, krb5_key key,
const krb5_crypto_iov *data, size_t num_data,
krb5_data *output)
{
return krb5int_hmac_keyblock(hash, &key->keyblock, data, num_data, output);
}
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