From 97ef3e4345e663627cfbbace8060afebab122301 Mon Sep 17 00:00:00 2001
From: Joseph Doherty <dohertj2@Josephs-MacBook-Pro.local>
Date: Sat, 3 Jan 2026 08:16:13 -0500
Subject: [PATCH] feat(infrastructure): implement RsaKeyService with tests

---
 .../Security/RsaKeyService.cs                 | 50 ++++++++++
 .../Security/RsaKeyServiceTests.cs            | 96 +++++++++++++++++++
 2 files changed, 146 insertions(+)
 create mode 100644 NEW/src/JdeScoping.Infrastructure/Security/RsaKeyService.cs
 create mode 100644 NEW/tests/JdeScoping.Infrastructure.Tests/Security/RsaKeyServiceTests.cs

diff --git a/NEW/src/JdeScoping.Infrastructure/Security/RsaKeyService.cs b/NEW/src/JdeScoping.Infrastructure/Security/RsaKeyService.cs
new file mode 100644
index 0000000..609550e
--- /dev/null
+++ b/NEW/src/JdeScoping.Infrastructure/Security/RsaKeyService.cs
@@ -0,0 +1,50 @@
+// NEW/src/JdeScoping.Infrastructure/Security/RsaKeyService.cs
+using System.Security.Cryptography;
+using JdeScoping.Core.Interfaces;
+
+namespace JdeScoping.Infrastructure.Security;
+
+/// <summary>
+/// RSA key service that auto-generates and persists keys.
+/// </summary>
+public class RsaKeyService : IRsaKeyService, IDisposable
+{
+    private readonly RSA _rsa;
+
+    /// <summary>
+    /// Creates a new RSA key service.
+    /// </summary>
+    /// <param name="keyFilePath">Path to persist the private key</param>
+    public RsaKeyService(string keyFilePath)
+    {
+        _rsa = RSA.Create(2048);
+
+        if (File.Exists(keyFilePath))
+        {
+            var keyBytes = File.ReadAllBytes(keyFilePath);
+            _rsa.ImportRSAPrivateKey(keyBytes, out _);
+        }
+        else
+        {
+            var privateKey = _rsa.ExportRSAPrivateKey();
+            var directory = Path.GetDirectoryName(keyFilePath);
+            if (!string.IsNullOrEmpty(directory))
+                Directory.CreateDirectory(directory);
+            File.WriteAllBytes(keyFilePath, privateKey);
+        }
+    }
+
+    /// <inheritdoc />
+    public string GetPublicKeyPem()
+        => _rsa.ExportSubjectPublicKeyInfoPem();
+
+    /// <inheritdoc />
+    public byte[] Decrypt(byte[] ciphertext)
+        => _rsa.Decrypt(ciphertext, RSAEncryptionPadding.OaepSHA256);
+
+    public void Dispose()
+    {
+        _rsa.Dispose();
+        GC.SuppressFinalize(this);
+    }
+}
diff --git a/NEW/tests/JdeScoping.Infrastructure.Tests/Security/RsaKeyServiceTests.cs b/NEW/tests/JdeScoping.Infrastructure.Tests/Security/RsaKeyServiceTests.cs
new file mode 100644
index 0000000..9512a34
--- /dev/null
+++ b/NEW/tests/JdeScoping.Infrastructure.Tests/Security/RsaKeyServiceTests.cs
@@ -0,0 +1,96 @@
+// NEW/tests/JdeScoping.Infrastructure.Tests/Security/RsaKeyServiceTests.cs
+using JdeScoping.Core.Interfaces;
+using JdeScoping.Infrastructure.Security;
+using Shouldly;
+
+namespace JdeScoping.Infrastructure.Tests.Security;
+
+public class RsaKeyServiceTests : IDisposable
+{
+    private readonly string _testKeyPath;
+
+    public RsaKeyServiceTests()
+    {
+        _testKeyPath = Path.Combine(Path.GetTempPath(), $"test-rsa-key-{Guid.NewGuid()}.bin");
+    }
+
+    public void Dispose()
+    {
+        if (File.Exists(_testKeyPath))
+            File.Delete(_testKeyPath);
+    }
+
+    [Fact]
+    public void GetPublicKeyPem_ReturnsValidPemFormat()
+    {
+        // Arrange
+        var service = new RsaKeyService(_testKeyPath);
+
+        // Act
+        var pem = service.GetPublicKeyPem();
+
+        // Assert
+        pem.ShouldStartWith("-----BEGIN PUBLIC KEY-----");
+        pem.ShouldEndWith("-----END PUBLIC KEY-----");
+    }
+
+    [Fact]
+    public void Constructor_WhenKeyFileMissing_GeneratesAndPersistsKey()
+    {
+        // Arrange - ensure file doesn't exist
+        File.Exists(_testKeyPath).ShouldBeFalse();
+
+        // Act
+        _ = new RsaKeyService(_testKeyPath);
+
+        // Assert
+        File.Exists(_testKeyPath).ShouldBeTrue();
+        new FileInfo(_testKeyPath).Length.ShouldBeGreaterThan(0);
+    }
+
+    [Fact]
+    public void Constructor_WhenKeyFileExists_LoadsSameKey()
+    {
+        // Arrange - create service to generate key
+        var service1 = new RsaKeyService(_testKeyPath);
+        var publicKey1 = service1.GetPublicKeyPem();
+
+        // Act - create new service instance
+        var service2 = new RsaKeyService(_testKeyPath);
+        var publicKey2 = service2.GetPublicKeyPem();
+
+        // Assert - same key loaded
+        publicKey2.ShouldBe(publicKey1);
+    }
+
+    [Fact]
+    public void Decrypt_WithValidCiphertext_ReturnsPlaintext()
+    {
+        // Arrange
+        var service = new RsaKeyService(_testKeyPath);
+        var plaintext = "Hello, World!"u8.ToArray();
+
+        // Encrypt using public key (simulating what client does)
+        using var rsa = System.Security.Cryptography.RSA.Create();
+        rsa.ImportFromPem(service.GetPublicKeyPem());
+        var ciphertext = rsa.Encrypt(plaintext, System.Security.Cryptography.RSAEncryptionPadding.OaepSHA256);
+
+        // Act
+        var decrypted = service.Decrypt(ciphertext);
+
+        // Assert
+        decrypted.ShouldBe(plaintext);
+    }
+
+    [Fact]
+    public void Decrypt_WithInvalidCiphertext_ThrowsCryptographicException()
+    {
+        // Arrange
+        var service = new RsaKeyService(_testKeyPath);
+        var invalidCiphertext = new byte[] { 1, 2, 3, 4, 5 };
+
+        // Act & Assert
+        Should.Throw<System.Security.Cryptography.CryptographicException>(
+            () => service.Decrypt(invalidCiphertext));
+    }
+}