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// Copyright (C) 2014-2016 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#include <cryptolink.h>
#include <cryptolink/crypto_hmac.h>
#include <boost/scoped_ptr.hpp>
#include <openssl/hmac.h>
#include <cryptolink/openssl_common.h>
#define KEA_HMAC
#include <cryptolink/openssl_compat.h>
#include <cstring>
namespace isc {
namespace cryptolink {
/// @brief OpenSSL implementation of HMAC. Each method is the counterpart
/// of the HMAC corresponding method.
class HMACImpl {
public:
/// @brief Constructor from a secret and a hash algorithm
///
/// See constructor of the @ref isc::cryptolink::HMAC class for details.
///
/// @param secret The secret to sign with
/// @param secret_len The length of the secret
/// @param hash_algorithm The hash algorithm
explicit HMACImpl(const void* secret, size_t secret_len,
const HashAlgorithm hash_algorithm)
: hash_algorithm_(hash_algorithm), md_() {
const EVP_MD* algo = ossl::getHashAlgorithm(hash_algorithm);
if (algo == 0) {
isc_throw(UnsupportedAlgorithm,
"Unknown hash algorithm: " <<
static_cast<int>(hash_algorithm));
}
if (secret_len == 0) {
isc_throw(BadKey, "Bad HMAC secret length: 0");
}
md_ = HMAC_CTX_new();
if (md_ == 0) {
isc_throw(LibraryError, "HMAC_CTX_new");
}
if (!HMAC_Init_ex(md_, secret,
static_cast<int>(secret_len),
algo, NULL)) {
isc_throw(LibraryError, "HMAC_Init_ex");
}
}
/// @brief Destructor
~HMACImpl() {
if (md_) {
HMAC_CTX_free(md_);
}
md_ = 0;
}
/// @brief Returns the HashAlgorithm of the object
HashAlgorithm getHashAlgorithm() const {
return (hash_algorithm_);
}
/// @brief Returns the output size of the digest
///
/// @return output size of the digest
size_t getOutputLength() const {
int size = HMAC_size(md_);
if (size < 0) {
isc_throw(LibraryError, "HMAC_size");
}
return (static_cast<size_t>(size));
}
/// @brief Add data to digest
///
/// See @ref isc::cryptolink::HMAC::update() for details.
void update(const void* data, const size_t len) {
if (!HMAC_Update(md_,
static_cast<const unsigned char*>(data),
len)) {
isc_throw(LibraryError, "HMAC_Update");
}
}
/// @brief Calculate the final signature
///
/// See @ref isc::cryptolink::HMAC::sign() for details.
void sign(isc::util::OutputBuffer& result, size_t len) {
size_t size = getOutputLength();
ossl::SecBuf<unsigned char> digest(size);
if (!HMAC_Final(md_, &digest[0], NULL)) {
isc_throw(LibraryError, "HMAC_Final");
}
if (len > size) {
len = size;
}
result.writeData(&digest[0], len);
}
/// @brief Calculate the final signature
///
/// See @ref isc::cryptolink::HMAC::sign() for details.
void sign(void* result, size_t len) {
size_t size = getOutputLength();
ossl::SecBuf<unsigned char> digest(size);
if (!HMAC_Final(md_, &digest[0], NULL)) {
isc_throw(LibraryError, "HMAC_Final");
}
if (len > size) {
len = size;
}
std::memcpy(result, &digest[0], len);
}
/// @brief Calculate the final signature
///
/// See @ref isc::cryptolink::HMAC::sign() for details.
std::vector<uint8_t> sign(size_t len) {
size_t size = getOutputLength();
ossl::SecBuf<unsigned char> digest(size);
if (!HMAC_Final(md_, &digest[0], NULL)) {
isc_throw(LibraryError, "HMAC_Final");
}
if (len < size) {
digest.resize(len);
}
return (std::vector<uint8_t>(digest.begin(), digest.end()));
}
/// @brief Verify an existing signature
///
/// See @ref isc::cryptolink::HMAC::verify() for details.
bool verify(const void* sig, size_t len) {
// Check the length
size_t size = getOutputLength();
if (len < 10 || len < size / 2) {
return (false);
}
// Get the digest from a copy of the context
HMAC_CTX* tmp = HMAC_CTX_new();
if (tmp == 0) {
isc_throw(LibraryError, "HMAC_CTX_new");
}
if (!HMAC_CTX_copy(tmp, md_)) {
HMAC_CTX_free(tmp);
isc_throw(LibraryError, "HMAC_CTX_copy");
}
ossl::SecBuf<unsigned char> digest(size);
if (!HMAC_Final(tmp, &digest[0], NULL)) {
HMAC_CTX_free(tmp);
isc_throw(LibraryError, "HMAC_Final");
}
HMAC_CTX_free(tmp);
if (len > size) {
len = size;
}
return (digest.same(sig, len));
}
private:
/// @brief The hash algorithm
HashAlgorithm hash_algorithm_;
/// @brief The protected pointer to the OpenSSL HMAC_CTX structure
HMAC_CTX* md_;
};
HMAC::HMAC(const void* secret, size_t secret_length,
const HashAlgorithm hash_algorithm)
{
impl_ = new HMACImpl(secret, secret_length, hash_algorithm);
}
HMAC::~HMAC() {
delete impl_;
}
HashAlgorithm
HMAC::getHashAlgorithm() const {
return (impl_->getHashAlgorithm());
}
size_t
HMAC::getOutputLength() const {
return (impl_->getOutputLength());
}
void
HMAC::update(const void* data, const size_t len) {
impl_->update(data, len);
}
void
HMAC::sign(isc::util::OutputBuffer& result, size_t len) {
impl_->sign(result, len);
}
void
HMAC::sign(void* result, size_t len) {
impl_->sign(result, len);
}
std::vector<uint8_t>
HMAC::sign(size_t len) {
return impl_->sign(len);
}
bool
HMAC::verify(const void* sig, const size_t len) {
return (impl_->verify(sig, len));
}
} // namespace cryptolink
} // namespace isc
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