8f76a3ac31
An Argon2 verify is ~8.9 ms of frozen world per login attempt, successful or not, so a credential flood is a full-cost stall per packet without needing valid credentials. Measurement puts the on-loop saving at 3.5-8.9 ms: the hand-off costs ~220 ns, and the only real residue is the loop's own work slowing while a memory-hard KDF evicts shared L3. One worker, not a pool. The per-login contention tax falls with concurrency while total loop damage rises, so one hasher harms the loop least; and a single hasher cannot cost the loop more than the inline verify under any scheduling regime, because at worst it takes an equal share of one core. That bound is what lets the measurement extrapolate to hardware we cannot inspect, and a pool breaks it. It also caps live Argon2 arenas at one, which answers memory exhaustion without a separate mechanism. Scoped to Argon2-stored accounts. SHA and MD5 protections share a HashAlgorithm instance whose ComputeHash is not thread safe, and they cost microseconds anyway. Their one-time rehash into Argon2 stays on the loop too: it costs a migrating account a single 8.9 ms login exactly as today. The worker parks on an AutoResetEvent and never spins. The spin in SerializationThreadWorker exists to wait on a producer mid-drain; there is no such race here, so this is strictly cheaper at idle. It yields while the world is in PendingSave or Saving -- PendingSave included, because the serialization threads are already awake and spinning on an empty queue by then. Phrase derivation moves to AccountSecurity.DerivePhrase so verification and rehash cannot disagree about the rule, which is the shape of the lockout fixed in #2562. ApplyPasswordUpgrade refuses to write when the stored hash changed while the verify ran, so a password set mid-flight is not replaced by a rehash of the one it superseded.
65 lines
3.2 KiB
C#
65 lines
3.2 KiB
C#
/*************************************************************************
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* ModernUO *
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* Copyright 2019-2026 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: Argon2PasswordProtection.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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using System.Security.Cryptography;
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namespace Server.Accounting.Security;
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public class Argon2PasswordProtection : IPasswordProtection
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{
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public static IPasswordProtection Instance = new Argon2PasswordProtection();
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/// <summary>
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/// An instance sharing no state with <see cref="Instance"/>. Verification is static-backed and
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/// safe to call from anywhere, but hashing draws its salt from a per-instance
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/// <see cref="RandomNumberGenerator"/>, so a thread that hashes off the game loop takes its own
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/// rather than racing the loop for that one field.
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/// </summary>
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public static IPasswordProtection CreateIsolated() => new Argon2PasswordProtection();
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// 16 MiB at t=1 is cheaper than 8 MiB at t=3 (8.5 ms vs 10.1 ms) and twice as memory-hard, which
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// is what resists GPU and ASIC cracking. p=1: native argon2 spawns a thread per lane.
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private readonly Argon2PasswordHasher _passwordHasher = new(
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time: 1,
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memory: 16384,
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parallel: 1,
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type: Argon2Type.Argon2id,
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rng: RandomNumberGenerator.Create()
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);
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public string EncryptPassword(string plainPassword) =>
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_passwordHasher.Hash(plainPassword);
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public bool ValidatePassword(string encryptedPassword, string plainPassword) =>
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_passwordHasher.Verify(encryptedPassword, plainPassword);
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// Verification uses the parameters embedded in the PHC string, not the configured ones, so
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// comparing them is what lets a parameter change reach existing accounts.
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public bool NeedsRehash(string encryptedPassword)
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{
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// Unparseable but verified: a format this build does not understand, so rewrite it.
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if (!Argon2PasswordHasher.TryExtractMetadataValues(encryptedPassword, out var values))
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{
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return true;
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}
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return values.ArgonType != _passwordHasher.ArgonType
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|| values.MemoryCost != _passwordHasher.MemoryCost
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|| values.TimeCost != _passwordHasher.TimeCost
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|| values.Parallelism != _passwordHasher.Parallelism
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|| values.HashLength != (int)_passwordHasher.HashLength
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|| values.SaltLength != (int)_passwordHasher.SaltLength;
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}
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}
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