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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012-2017 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License Version 3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
#ifndef OPENVPN_APPLECRYPTO_CRYPTO_HMAC_H
#define OPENVPN_APPLECRYPTO_CRYPTO_HMAC_H
// Wrap the Apple HMAC API defined in <CommonCrypto/CommonHMAC.h> so that
// it can be used as part of the crypto layer of the OpenVPN core.
#include <string>
#include <cstring>
#include <CommonCrypto/CommonHMAC.h>
#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/applecrypto/crypto/digest.hpp>
namespace openvpn {
namespace AppleCrypto {
class HMACContext
{
HMACContext(const HMACContext&) = delete;
HMACContext& operator=(const HMACContext&) = delete;
public:
OPENVPN_EXCEPTION(digest_cannot_be_used_with_hmac);
OPENVPN_SIMPLE_EXCEPTION(hmac_uninitialized);
OPENVPN_SIMPLE_EXCEPTION(hmac_keysize_error);
enum {
MAX_HMAC_SIZE = DigestContext::MAX_DIGEST_SIZE,
MAX_HMAC_KEY_SIZE = 128,
};
HMACContext()
{
state = PRE;
}
HMACContext(const CryptoAlgs::Type digest, const unsigned char *key, const size_t key_size)
{
init(digest, key, key_size);
}
~HMACContext()
{
}
void init(const CryptoAlgs::Type digest, const unsigned char *key, const size_t key_size)
{
state = PRE;
info = DigestContext::digest_type(digest);
digest_size_ = CryptoAlgs::size(digest);
hmac_alg = info->hmac_alg();
if (hmac_alg == DigestInfo::NO_HMAC_ALG)
throw digest_cannot_be_used_with_hmac(info->name());
if (key_size > MAX_HMAC_KEY_SIZE)
throw hmac_keysize_error();
std::memcpy(key_, key, key_size_ = key_size);
state = PARTIAL;
}
void reset() // Apple HMAC API is missing reset method, so we have to reinit
{
cond_reset(true);
}
void update(const unsigned char *in, const size_t size)
{
cond_reset(false);
CCHmacUpdate(&ctx, in, size);
}
size_t final(unsigned char *out)
{
cond_reset(false);
CCHmacFinal(&ctx, out);
return digest_size_;
}
size_t size() const
{
if (!is_initialized())
throw hmac_uninitialized();
return digest_size_;
}
bool is_initialized() const
{
return state >= PARTIAL;
}
private:
void cond_reset(const bool force_init)
{
switch (state)
{
case PRE:
throw hmac_uninitialized();
case READY:
if (!force_init)
return;
case PARTIAL:
CCHmacInit(&ctx, hmac_alg, key_, key_size_);
state = READY;
}
}
enum State {
PRE=0,
PARTIAL,
READY
};
int state;
const DigestInfo *info;
CCHmacAlgorithm hmac_alg;
size_t key_size_;
size_t digest_size_;
unsigned char key_[MAX_HMAC_KEY_SIZE];
CCHmacContext ctx;
};
}
}
#endif