Core/Authserver: Split SRP6 into its own file (PR #25131)

(cherry picked from commit 7f7fa8b23d71297f75ff4ca3c1d6e38333a5cc76)

3 files changed, 237 insertions, 0 deletions

diff --git a/src/common/Cryptography/Authentication/AuthDefines.h b/src/common/Cryptography/Authentication/AuthDefines.h
new file mode 100644
index 00000000000..a32de20dcc6
--- /dev/null
+++ b/src/common/Cryptography/Authentication/AuthDefines.h
@@ -0,0 +1,27 @@
+/*
+ * 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/>.
+ */
+
+#ifndef TRINITY_AUTHDEFINES_H
+#define TRINITY_AUTHDEFINES_H
+
+#include "Define.h"
+#include <array>
+
+constexpr size_t SESSION_KEY_LENGTH = 40;
+using SessionKey = std::array<uint8, SESSION_KEY_LENGTH>;
+
+#endif
diff --git a/src/common/Cryptography/Authentication/SRP6.cpp b/src/common/Cryptography/Authentication/SRP6.cpp
new file mode 100644
index 00000000000..c8b80d58f9b
--- /dev/null
+++ b/src/common/Cryptography/Authentication/SRP6.cpp
@@ -0,0 +1,118 @@
+/*
+ * 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 "SRP6.h"
+#include "CryptoRandom.h"
+#include "Util.h"
+#include <algorithm>
+#include <functional>
+
+using SHA1 = Trinity::Crypto::SHA1;
+using SRP6 = Trinity::Crypto::SRP6;
+
+/*static*/ std::array<uint8, 1> const SRP6::g = { 7 };
+/*static*/ std::array<uint8, 32> const SRP6::N = HexStrToByteArray<32>("894B645E89E1535BBDAD5B8B290650530801B18EBFBF5E8FAB3C82872A3E9BB7", true);
+/*static*/ BigNumber const SRP6::_g(SRP6::g);
+/*static*/ BigNumber const SRP6::_N(N);
+
+/*static*/ std::pair<SRP6::Salt, SRP6::Verifier> SRP6::MakeRegistrationData(std::string const& username, std::string const& password)
+{
+    std::pair<SRP6::Salt, SRP6::Verifier> res;
+    Crypto::GetRandomBytes(res.first); // random salt
+    res.second = CalculateVerifier(username, password, res.first);
+    return res;
+}
+
+/*static*/ std::pair<SRP6::Salt, SRP6::Verifier> SRP6::MakeRegistrationDataFromHash_DEPRECATED_DONOTUSE(SHA1::Digest const& hash)
+{
+    std::pair<SRP6::Salt, SRP6::Verifier> res;
+    Crypto::GetRandomBytes(res.first);
+    res.second = CalculateVerifierFromHash(hash, res.first);
+    return res;
+}
+
+/*static*/ SRP6::Verifier SRP6::CalculateVerifier(std::string const& username, std::string const& password, SRP6::Salt const& salt)
+{
+    // v = g ^ H(s || H(u || ':' || p)) mod N
+    return CalculateVerifierFromHash(SHA1::GetDigestOf(username, ":", password), salt);
+}
+
+// merge this into CalculateVerifier once the sha_pass hack finally gets nuked from orbit
+/*static*/ SRP6::Verifier SRP6::CalculateVerifierFromHash(SHA1::Digest const& hash, SRP6::Salt const& salt)
+{
+    return _g.ModExp(SHA1::GetDigestOf(salt, hash), _N).ToByteArray<32>(false);
+}
+
+/*static*/ SessionKey SRP6::SHA1Interleave(SRP6::EphemeralKey const& S)
+{
+    // split S into two buffers
+    std::array<uint8, EPHEMERAL_KEY_LENGTH/2> buf0, buf1;
+    for (size_t i = 0; i < EPHEMERAL_KEY_LENGTH/2; ++i)
+    {
+        buf0[i] = S[2 * i + 0];
+        buf1[i] = S[2 * i + 1];
+    }
+
+    // find position of first nonzero byte
+    size_t p = 0;
+    while (p < EPHEMERAL_KEY_LENGTH && !S[p]) ++p;
+    if (p & 1) ++p; // skip one extra byte if p is odd
+    p /= 2; // offset into buffers
+
+    // hash each of the halves, starting at the first nonzero byte
+    SHA1::Digest const hash0 = SHA1::GetDigestOf(buf0.data() + p, EPHEMERAL_KEY_LENGTH/2 - p);
+    SHA1::Digest const hash1 = SHA1::GetDigestOf(buf1.data() + p, EPHEMERAL_KEY_LENGTH/2 - p);
+
+    // stick the two hashes back together
+    SessionKey K;
+    for (size_t i = 0; i < SHA1::DIGEST_LENGTH; ++i)
+    {
+        K[2 * i + 0] = hash0[i];
+        K[2 * i + 1] = hash1[i];
+    }
+    return K;
+}
+
+SRP6::SRP6(std::string const& username, Salt const& salt, Verifier const& verifier)
+    : _I(SHA1::GetDigestOf(username)), _b(Crypto::GetRandomBytes<19>()), _v(verifier, false), s(salt), B(_B(_b, _v)) {}
+
+Optional<SessionKey> SRP6::VerifyChallengeResponse(EphemeralKey const& A, SHA1::Digest const& clientM)
+{
+    ASSERT(!_used, "A single SRP6 object must only ever be used to verify ONCE!");
+    _used = true;
+
+    BigNumber const _A(A);
+    if ((_A % _N).IsZero())
+        return {};
+
+    BigNumber const u(SHA1::GetDigestOf(A, B));
+    EphemeralKey const S = (_A * (_v.ModExp(u, _N))).ModExp(_b, N).ToByteArray<32>();
+
+    SessionKey K = SHA1Interleave(S);
+
+    // NgHash = H(N) xor H(g)
+    SHA1::Digest const NHash = SHA1::GetDigestOf(N);
+    SHA1::Digest const gHash = SHA1::GetDigestOf(g);
+    SHA1::Digest NgHash;
+    std::transform(NHash.begin(), NHash.end(), gHash.begin(), NgHash.begin(), std::bit_xor<>());
+
+    SHA1::Digest const ourM = SHA1::GetDigestOf(NgHash, _I, s, A, B, K);
+    if (ourM == clientM)
+        return K;
+    else
+        return {};
+}
diff --git a/src/common/Cryptography/Authentication/SRP6.h b/src/common/Cryptography/Authentication/SRP6.h
new file mode 100644
index 00000000000..3c511d6f7f3
--- /dev/null
+++ b/src/common/Cryptography/Authentication/SRP6.h
@@ -0,0 +1,92 @@
+/*
+ * 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/>.
+ */
+
+#ifndef TRINITY_SRP6_H
+#define TRINITY_SRP6_H
+
+#include "AuthDefines.h"
+#include "BigNumber.h"
+#include "Define.h"
+#include "Common.h"
+#include "CryptoHash.h"
+#include "Optional.h"
+#include <array>
+
+namespace Trinity
+{
+namespace Crypto
+{
+    class TC_COMMON_API SRP6
+    {
+        public:
+            static constexpr size_t SALT_LENGTH = 32;
+            using Salt = std::array<uint8, SALT_LENGTH>;
+            static constexpr size_t VERIFIER_LENGTH = 32;
+            using Verifier = std::array<uint8, VERIFIER_LENGTH>;
+            static constexpr size_t EPHEMERAL_KEY_LENGTH = 32;
+            using EphemeralKey = std::array<uint8, EPHEMERAL_KEY_LENGTH>;
+
+            static std::array<uint8, 1> const g;
+            static std::array<uint8, 32> const N;
+
+            // this is the old sha_pass_hash hack
+            // YOU SHOULD NEVER STORE THIS HASH, if you do you are breaking SRP6 guarantees
+            // use MakeRegistrationData instead
+            static std::pair<Salt, Verifier> MakeRegistrationDataFromHash_DEPRECATED_DONOTUSE(SHA1::Digest const& hash);
+
+            // username + password must be passed through Utf8ToUpperOnlyLatin FIRST!
+            static std::pair<Salt, Verifier> MakeRegistrationData(std::string const& username, std::string const& password);
+            // username + password must be passed through Utf8ToUpperOnlyLatin FIRST!
+            static bool CheckLogin(std::string const& username, std::string const& password, Salt const& salt, Verifier const& verifier)
+            {
+                return (verifier == CalculateVerifier(username, password, salt));
+            }
+
+            static SHA1::Digest GetSessionVerifier(EphemeralKey const& A, SHA1::Digest const& clientM, SessionKey const& K)
+            {
+                return SHA1::GetDigestOf(A, clientM, K);
+            }
+
+            SRP6(std::string const& username, Salt const& salt, Verifier const& verifier);
+            Optional<SessionKey> VerifyChallengeResponse(EphemeralKey const& A, SHA1::Digest const& clientM);
+
+        private:
+            bool _used = false; // a single instance can only be used to verify once
+
+            static Verifier CalculateVerifier(std::string const& username, std::string const& password, Salt const& salt);
+            static Verifier CalculateVerifierFromHash(SHA1::Digest const& hash, Salt const& salt);
+            static SessionKey SHA1Interleave(EphemeralKey const& S);
+
+            /* global algorithm parameters */
+            static BigNumber const _g; // a [g]enerator for the ring of integers mod N, algorithm parameter
+            static BigNumber const _N; // the modulus, an algorithm parameter; all operations are mod this
+
+            static EphemeralKey _B(BigNumber const& b, BigNumber const& v) { return ((_g.ModExp(b,_N) + (v * 3)) % N).ToByteArray<EPHEMERAL_KEY_LENGTH>(); }
+
+            /* per-instantiation parameters, set on construction */
+            SHA1::Digest const _I; // H(I) - the username, all uppercase
+            BigNumber const _b; // b - randomly chosen by the server, 19 bytes, never given out
+            BigNumber const _v; // v - the user's password verifier, derived from s + H(USERNAME || ":" || PASSWORD)
+
+        public:
+            Salt const s; // s - the user's password salt, random, used to calculate v on registration
+            EphemeralKey const B; // B = 3v + g^b
+    };
+}
+}
+
+#endif