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// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/hmac.h"
#include <nss.h>
#include <pk11pub.h>
#include "base/crypto/scoped_nss_types.h"
#include "base/logging.h"
#include "base/nss_util.h"
#include "base/scoped_ptr.h"
namespace base {
struct HMACPlatformData {
CK_MECHANISM_TYPE mechanism_;
ScopedPK11Slot slot_;
ScopedPK11SymKey sym_key_;
};
HMAC::HMAC(HashAlgorithm hash_alg)
: hash_alg_(hash_alg), plat_(new HMACPlatformData()) {
// Only SHA-1 and SHA-256 hash algorithms are supported.
switch (hash_alg_) {
case SHA1:
plat_->mechanism_ = CKM_SHA_1_HMAC;
break;
case SHA256:
plat_->mechanism_ = CKM_SHA256_HMAC;
break;
default:
NOTREACHED() << "Unsupported hash algorithm";
break;
}
}
bool HMAC::Init(const unsigned char *key, int key_length) {
base::EnsureNSSInit();
if (plat_->slot_.get()) {
// Init must not be called more than twice on the same HMAC object.
NOTREACHED();
return false;
}
plat_->slot_.reset(PK11_GetBestSlot(plat_->mechanism_, NULL));
if (!plat_->slot_.get()) {
NOTREACHED();
return false;
}
SECItem key_item;
key_item.type = siBuffer;
key_item.data = const_cast<unsigned char*>(key); // NSS API isn't const.
key_item.len = key_length;
plat_->sym_key_.reset(PK11_ImportSymKey(plat_->slot_.get(),
plat_->mechanism_,
PK11_OriginUnwrap,
CKA_SIGN,
&key_item,
NULL));
if (!plat_->sym_key_.get()) {
NOTREACHED();
return false;
}
return true;
}
HMAC::~HMAC() {
}
bool HMAC::Sign(const std::string& data,
unsigned char* digest,
int digest_length) {
if (!plat_->sym_key_.get()) {
// Init has not been called before Sign.
NOTREACHED();
return false;
}
SECItem param = { siBuffer, NULL, 0 };
ScopedPK11Context context(PK11_CreateContextBySymKey(plat_->mechanism_,
CKA_SIGN,
plat_->sym_key_.get(),
¶m));
if (!context.get()) {
NOTREACHED();
return false;
}
if (PK11_DigestBegin(context.get()) != SECSuccess) {
NOTREACHED();
return false;
}
if (PK11_DigestOp(context.get(),
reinterpret_cast<const unsigned char*>(data.data()),
data.length()) != SECSuccess) {
NOTREACHED();
return false;
}
unsigned int len = 0;
if (PK11_DigestFinal(context.get(),
digest, &len, digest_length) != SECSuccess) {
NOTREACHED();
return false;
}
return true;
}
} // namespace base
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