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/*
* This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* 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 General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "TOTP.h"
#include <openssl/evp.h>
#include <openssl/hmac.h>
static constexpr uint32 TOTP_INTERVAL = 30;
static constexpr uint32 HMAC_RESULT_SIZE = 20;
/*static*/ uint32 Trinity::Crypto::TOTP::GenerateToken(TOTP::Secret const& secret, time_t timestamp)
{
timestamp /= TOTP_INTERVAL;
unsigned char challenge[8];
for (int i = 8; i--; timestamp >>= 8)
challenge[i] = timestamp;
unsigned char digest[HMAC_RESULT_SIZE];
uint32 digestSize = HMAC_RESULT_SIZE;
HMAC(EVP_sha1(), secret.data(), secret.size(), challenge, 8, digest, &digestSize);
uint32 offset = digest[19] & 0xF;
uint32 truncated = (digest[offset] << 24) | (digest[offset + 1] << 16) | (digest[offset + 2] << 8) | (digest[offset + 3]);
truncated &= 0x7FFFFFFF;
return (truncated % 1000000);
}
/*static*/ bool Trinity::Crypto::TOTP::ValidateToken(TOTP::Secret const& secret, uint32 token)
{
time_t now = time(nullptr);
return (
(token == GenerateToken(secret, now - TOTP_INTERVAL)) ||
(token == GenerateToken(secret, now)) ||
(token == GenerateToken(secret, now + TOTP_INTERVAL))
);
}
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