IBKRTrader/tests/IBKRTrader.Tests/Security/SecretProtectionTests.cs

using FluentAssertions;
using IBKRTrader.Core.Security;

namespace IBKRTrader.Tests.Security;

/// <summary>
/// Testet die at-rest-Verschlüsselung. Nutzt den statischen SecretProtection-Zustand → nicht
/// parallelisierbar mit anderen Tests dieser Collection; Reset() im Finally hält es isoliert.
/// </summary>
[Trait("cat", "unit")]
[Collection("SecretProtection")]
public class SecretProtectionTests
{
    // 32-Byte-Key als Base64.
    private const string Key = "MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY=";

    [Fact]
    public void RoundTrip_EncryptsAndDecrypts()
    {
        try
        {
            SecretProtection.Configure(Key);
            var enc = SecretProtection.Protect("geheim123");

            enc.Should().StartWith("enc:v1:");
            enc.Should().NotContain("geheim123");
            SecretProtection.Unprotect(enc).Should().Be("geheim123");
        }
        finally { SecretProtection.Reset(); }
    }

    [Fact]
    public void Protect_IsIdempotent_ForAlreadyEncrypted()
    {
        try
        {
            SecretProtection.Configure(Key);
            var enc  = SecretProtection.Protect("x");
            var enc2 = SecretProtection.Protect(enc);   // nicht doppelt verschlüsseln
            enc2.Should().Be(enc);
        }
        finally { SecretProtection.Reset(); }
    }

    [Fact]
    public void NoKey_IsPassthrough_Plaintext()
    {
        SecretProtection.Reset();
        SecretProtection.Protect("klartext").Should().Be("klartext");
        SecretProtection.Unprotect("klartext").Should().Be("klartext");   // Alt-Klartext unverändert
    }

    [Fact]
    public void Unprotect_Encrypted_WithoutKey_Throws()
    {
        string enc;
        try
        {
            SecretProtection.Configure(Key);
            enc = SecretProtection.Protect("secret");
        }
        finally { SecretProtection.Reset(); }

        var act = () => SecretProtection.Unprotect(enc);
        act.Should().Throw<InvalidOperationException>();
    }

    [Fact]
    public void Unprotect_TamperedData_Throws()
    {
        try
        {
            SecretProtection.Configure(Key);
            var enc = SecretProtection.Protect("secret");

            // Erstes Base64-Zeichen des Payloads kippen → Nonce/Ciphertext korrupt, Base64 bleibt gültig.
            var payload = enc[SecretProtection.Prefix.Length..].ToCharArray();
            payload[0] = payload[0] == 'A' ? 'B' : 'A';
            var tampered = SecretProtection.Prefix + new string(payload);

            var act = () => SecretProtection.Unprotect(tampered);
            act.Should().Throw<InvalidOperationException>();
        }
        finally { SecretProtection.Reset(); }
    }
}