feat(Core/Authserver): TOTP rewrite (#5620)

src/common/Cryptography/TOTP.cpp

@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2016+  AzerothCore <www.azerothcore.org>, released under GNU AGPL v3 license: https://github.com/azerothcore/azerothcore-wotlk/blob/master/LICENSE-AGPL3
+ * Copyright (C) 2021+  WarheadCore <https://github.com/WarheadCore>
+ */
+
+#include "TOTP.h"
+#include <cstring>
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
+
+constexpr std::size_t acore::Crypto::TOTP::RECOMMENDED_SECRET_LENGTH;
+static constexpr uint32 TOTP_INTERVAL = 30;
+static constexpr uint32 HMAC_RESULT_SIZE = 20;
+
+/*static*/ uint32 acore::Crypto::TOTP::GenerateToken(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 acore::Crypto::TOTP::ValidateToken(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))
+    );
+}