davide
27231c8eec
CertificatePinStore.Load threw on a corrupted pin file, blocking every SSL connection until the user manually deleted it; EncryptedFile.IsEncrypted threw on valid JSON with a non-object root or invalid UTF-16 instead of returning false. Both now degrade gracefully. Found by property-based tests while extending the test suite.
84 lines
2.6 KiB
C#
84 lines
2.6 KiB
C#
using System.Security.Cryptography;
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using System.Security.Cryptography.X509Certificates;
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using System.Text.Json;
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namespace PalladiumWallet.Core.Net;
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/// <summary>
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/// TLS "trust on first use" pinning (blueprint §9): on the first contact the
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/// server certificate's SHA-256 fingerprint is saved; on subsequent ones it is
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/// compared. If it changes, the connection must be rejected and the user can
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/// unlock with an explicit reset (typical case: renewed self-signed server).
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/// </summary>
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public sealed class CertificatePinStore(string filePath)
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{
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private readonly object _lock = new();
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public static string Fingerprint(X509Certificate certificate) =>
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Convert.ToHexString(SHA256.HashData(certificate.GetRawCertData())).ToLowerInvariant();
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/// <summary>
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/// TOFU check: true if the certificate is the one already seen (or if it is the
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/// first contact, in which case it is saved). False = certificate changed.
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/// </summary>
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public bool VerifyOrPin(string host, int port, X509Certificate certificate)
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{
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var key = $"{host}:{port}";
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var fingerprint = Fingerprint(certificate);
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lock (_lock)
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{
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var pins = Load();
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if (pins.TryGetValue(key, out var pinned))
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return pinned == fingerprint;
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pins[key] = fingerprint;
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Save(pins);
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return true;
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}
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}
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/// <summary>Reset the saved certificate for a server ("reset SSL certificates", §9).</summary>
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public bool Reset(string host, int port)
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{
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lock (_lock)
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{
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var pins = Load();
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if (!pins.Remove($"{host}:{port}"))
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return false;
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Save(pins);
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return true;
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}
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}
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public void ResetAll()
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{
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lock (_lock)
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{
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if (File.Exists(filePath))
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File.Delete(filePath);
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}
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}
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private Dictionary<string, string> Load()
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{
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if (!File.Exists(filePath))
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return [];
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try
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{
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return JsonSerializer.Deserialize<Dictionary<string, string>>(File.ReadAllText(filePath)) ?? [];
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}
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catch (JsonException)
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{
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// A corrupt pin file must not make every SSL connection fail forever:
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// fall back to first-contact TOFU (same trust level as the bootstrap).
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return [];
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}
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}
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private void Save(Dictionary<string, string> pins)
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{
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Directory.CreateDirectory(Path.GetDirectoryName(filePath)!);
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File.WriteAllText(filePath, JsonSerializer.Serialize(pins,
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new JsonSerializerOptions { WriteIndented = true }));
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}
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}
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