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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* lib/crypto/nss/hmac.c */
/*
* Copyright (c) 2010 Red Hat, Inc.
* All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* * Neither the name of Red Hat, Inc., nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "crypto_int.h"
#include "nss_gen.h"
#include "pk11pub.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 CK_MECHANISM_TYPE
digest_to_hmac(const struct krb5_hash_provider *hash)
{
/* use strcmp so we don't confuse SHA1 with SHA128 */
/* handle the obvious cases first */
if (!strcmp(hash->hash_name, "SHA1"))
return CKM_SHA_1_HMAC;
if (!strcmp(hash->hash_name, "MD5"))
return CKM_MD5_HMAC;
return CKM_INVALID_MECHANISM;
}
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)
{
unsigned int i = 0;
CK_MECHANISM_TYPE mech;
PK11Context *ctx = NULL;
krb5_error_code ret = 0;
SECStatus rv;
SECItem param;
if (output->length < hash->hashsize)
return KRB5_BAD_MSIZE;
mech = digest_to_hmac(hash);
if (mech == CKM_INVALID_MECHANISM)
return KRB5_CRYPTO_INTERNAL; /* unsupported alg */
ret = k5_nss_gen_import(key, mech, CKA_SIGN);
if (ret != 0)
return ret;
param.data = NULL;
param.len = 0;
ctx = k5_nss_create_context(key, mech, CKA_SIGN, ¶m);
if (ctx == NULL)
goto fail;
rv = PK11_DigestBegin(ctx);
if (rv != SECSuccess)
goto fail;
for (i=0; i < num_data; i++) {
const krb5_crypto_iov *iov = &data[i];
if (iov->data.length && SIGN_IOV(iov)) {
rv = PK11_DigestOp(ctx,(const unsigned char*)iov->data.data,
iov->data.length);
if (rv != SECSuccess)
goto fail;
}
}
rv = PK11_DigestFinal(ctx, (unsigned char *) output->data, &output->length,
output->length);
if (rv != SECSuccess)
goto fail;
PK11_DestroyContext(ctx, PR_TRUE);
return 0;
fail:
ret = k5_nss_map_last_error();
if (ctx)
PK11_DestroyContext(ctx, PR_TRUE);
return ret;
}
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)
{
krb5_key key;
krb5_error_code code;
if (keyblock->length > hash->blocksize)
return KRB5_CRYPTO_INTERNAL;
memset(&key, 0, sizeof(key));
code = krb5_k_create_key(NULL, keyblock, &key);
if (code)
return code;
code = krb5int_hmac(hash, key, data, num_data, output);
krb5_k_free_key(NULL, key);
return code;
}
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