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// Copyright (C) 2011-2019 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 <config.h>
#include <cryptolink.h>
#include <cryptolink/crypto_hmac.h>
#include <boost/scoped_ptr.hpp>
#include <botan/hmac.h>
#include <botan/lookup.h>
#include <cryptolink/botan_common.h>
namespace isc {
namespace cryptolink {
/// @brief Botan 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), hmac_() {
Botan::HashFunction* hash;
try {
const std::string& name =
btn::getHashAlgorithmName(hash_algorithm);
std::unique_ptr<Botan::HashFunction> hash_ptr =
Botan::HashFunction::create(name);
if (hash_ptr) {
hash = hash_ptr.release();
} else {
throw Botan::Algorithm_Not_Found(name);
}
} catch (const Botan::Algorithm_Not_Found&) {
isc_throw(UnsupportedAlgorithm,
"Unknown hash algorithm: " <<
static_cast<int>(hash_algorithm));
} catch (const Botan::Exception& exc) {
isc_throw(LibraryError, "Botan error: " << exc.what());
}
hmac_.reset(new Botan::HMAC(hash));
// If the key length is larger than the block size, we hash the
// key itself first.
try {
// use a temp var so we don't have blocks spanning
// preprocessor directives
size_t block_length = hash->hash_block_size();
if (secret_len > block_length) {
Botan::secure_vector<Botan::byte> hashed_key =
hash->process(static_cast<const Botan::byte*>(secret),
secret_len);
hmac_->set_key(&hashed_key[0], hashed_key.size());
} else {
// Botan 1.8 considers len 0 a bad key. 1.9 does not,
// but we won't accept it anyway, and fail early
if (secret_len == 0) {
isc_throw(BadKey, "Bad HMAC secret length: 0");
}
hmac_->set_key(static_cast<const Botan::byte*>(secret),
secret_len);
}
} catch (const Botan::Invalid_Key_Length& ikl) {
isc_throw(BadKey, ikl.what());
} catch (const Botan::Exception& exc) {
isc_throw(LibraryError, "Botan error: " << exc.what());
}
}
/// @brief Destructor
~HMACImpl() {
}
/// @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 {
return (hmac_->output_length());
}
/// @brief Add data to digest
///
/// See @ref isc::cryptolink::HMAC::update() for details.
void update(const void* data, const size_t len) {
try {
hmac_->update(static_cast<const Botan::byte*>(data), len);
} catch (const Botan::Exception& exc) {
isc_throw(LibraryError, "Botan error: " << exc.what());
}
}
/// @brief Calculate the final signature
///
/// See @ref isc::cryptolink::HMAC::sign() for details.
void sign(isc::util::OutputBuffer& result, size_t len) {
try {
Botan::secure_vector<Botan::byte> b_result(hmac_->final());
if (len > b_result.size()) {
len = b_result.size();
}
result.writeData(&b_result[0], len);
} catch (const Botan::Exception& exc) {
isc_throw(LibraryError, "Botan error: " << exc.what());
}
}
/// @brief Calculate the final signature
///
/// See @ref isc::cryptolink::HMAC::sign() for details.
void sign(void* result, size_t len) {
try {
Botan::secure_vector<Botan::byte> b_result(hmac_->final());
size_t output_size = getOutputLength();
if (output_size > len) {
output_size = len;
}
std::memcpy(result, &b_result[0], output_size);
} catch (const Botan::Exception& exc) {
isc_throw(LibraryError, "Botan error: " << exc.what());
}
}
/// @brief Calculate the final signature
///
/// See @ref isc::cryptolink::HMAC::sign() for details.
std::vector<uint8_t> sign(size_t len) {
try {
Botan::secure_vector<Botan::byte> b_result(hmac_->final());
if (len > b_result.size()) {
len = b_result.size();
}
// Return vector with content. Construct &b_result[len] attempts
// to get an address of one element beyond the b_result. Replaced
// with the address of first element + len
return (std::vector<uint8_t>(&b_result[0], &b_result[0]+len));
} catch (const Botan::Exception& exc) {
isc_throw(LibraryError, "Botan error: " << exc.what());
}
}
/// @brief Verify an existing signature
///
/// See @ref isc::cryptolink::HMAC::verify() for details.
bool verify(const void* sig, size_t len) {
// Botan's verify_mac checks if len matches the output_length,
// which causes it to fail for truncated signatures, so we do
// the check ourselves
try {
size_t size = getOutputLength();
if (len < 10 || len < size / 2) {
return (false);
}
if (len > size) {
len = size;
}
if (digest_.size() == 0) {
digest_ = hmac_->final();
}
return (Botan::same_mem(&digest_[0],
static_cast<const unsigned char*>(sig),
len));
} catch (const Botan::Exception& exc) {
isc_throw(LibraryError, "Botan error: " << exc.what());
}
}
private:
/// @brief The hash algorithm
HashAlgorithm hash_algorithm_;
/// @brief The protected pointer to the Botan HMAC object
boost::scoped_ptr<Botan::HMAC> hmac_;
/// @brief The digest cache for multiple verify
Botan::secure_vector<Botan::byte> digest_;
};
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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