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> ⚠️ **Rollback hazard — one-way door once logins are taken.** Serialization is unchanged, so a save > written by this build still *loads* on the previous one. Its contents do not survive the trip: on > its first successful login each account is rehashed to `$argon2id$`, and the previous build ships > Argon2.Bindings 1.19.0, whose `Verify` is gated by the verifier's own configured type and answers > `false` for an `$argon2id$` hash. **After a shard running this build has accepted logins, do not > roll back past this commit** — every account that logged in is locked out on the older binary, and > the only recovery is rolling forward again or resetting passwords by hand. Roll back only from a > save taken before the first post-deploy login. Requires [Argon2.Bindings 1.20.0](https://github.com/modernuo/Argon2.Bindings/pull/14), now published. ## What - Consume `Argon2.Bindings` 1.20.0, which resolves the Argon2 type from the stored PHC string rather than from the verifier's own configuration. - Default to **Argon2id, m=16384, t=1, p=1** — 8.51 ms against the old Argon2i 8 MiB t=3 at 10.11 ms. Cheaper *and* stronger. - Rehash on a successful login whenever the stored parameters are stale, not only when the algorithm changes. - Fix `SetPassword`, which derived the password phrase from the outgoing algorithm while storing it under the incoming one. ## Why **Verification was gated by the verifier's configured type.** `Verify` passed the instance's own `ArgonType` to native `argon2_verify`, whose `decode_string` rejects a disagreeing `$argon2i$`/`$argon2id$` prefix and returns `DECODING_FAIL` — folded into `false`, the same answer as a wrong password. Switching the default type would have locked out every existing account, and `VerifyAndUpdate` could not have migrated them either: it delegates to the same type-fixed `Verify` and never compared `ArgonType`. Fixed upstream in 1.20.0. The pinned legacy-`$argon2i$` test here fails on 1.19.0 for exactly that reason, which is what makes the package bump load-bearing rather than incidental. **Changing the defaults would otherwise have reached nobody.** Argon2's PHC string embeds `m`, `t` and `p`, so verification uses the parameters stored with each account, not the configured ones — and verification is the hot path. `CheckPassword` only rehashed when the *algorithm* changed, never when its cost parameters did, so on an established shard the new defaults would have applied to new accounts only. `IPasswordProtection.NeedsRehash` closes that: it defaults to `false`, so PBKDF2 and the `HashAlgorithm` protections are untouched — only Argon2 carries its cost inside the stored value. **`SetPassword` picked the phrase rule from the wrong algorithm.** SHA1 and SHA2 salt the phrase with the username; Argon2 and PBKDF2 do not. It chose the rule from the *outgoing* algorithm while storing under the *incoming* one, so any algorithm change wrote a credential its own next verify could not reproduce. It now assigns `PasswordAlgorithm` first and derives the phrase from that. Note this ordering is load-bearing and invisible — `UpgradingAlgorithm_DoesNotLockTheAccountOut` is what pins it. ## Cost Verification is re-derivation, so these are login numbers. A full login calls `CheckPassword` twice — `AccountLogin` (0x80) then `GameLogin` (0x91): **~20 ms before, ~17 ms after**, plus a one-time ~8.5 ms rehash on each account's migrating login. That cost is still paid on the game loop. Moving hashing off-loop is deliberately **not** in this PR — it needs a pending-auth state in the login handlers, bounding of in-flight hashes, and login rate limiting.
58 lines
2.8 KiB
C#
58 lines
2.8 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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// 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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// The PHC string carries the parameters it was hashed with, so verification uses those rather
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// than the configured ones. Comparing them is what lets a parameter change reach existing
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// 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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