feat(secrets): AES-256-GCM envelope cipher with AAD binding

2026-07-15 16:34:46 -04:00
parent 16b32257f5
commit b784c7117f
4 changed files with 321 additions and 1 deletions
@@ -0,0 +1,45 @@
+using System.Security.Cryptography;
+using ZB.MOM.WW.Secrets.Abstractions;
+
+namespace ZB.MOM.WW.Secrets.Tests.Fakes;
+
+/// <summary>
+/// A hand-written <see cref="IMasterKeyProvider"/> test double (the family does not use Moq).
+/// Generates a random 32-byte master key once at construction and returns it stably, alongside
+/// a caller-supplied <see cref="KekId"/>. Two instances with the same <see cref="KekId"/> string
+/// still hold different key bytes, which lets a test prove that a matching KEK id but wrong key
+/// material fails closed.
+/// </summary>
+public sealed class FakeMasterKeyProvider : IMasterKeyProvider
+{
+    private readonly byte[] _key;
+
+    /// <summary>
+    /// Creates a provider with a freshly generated random 32-byte master key and the given
+    /// <paramref name="kekId"/>.
+    /// </summary>
+    /// <param name="kekId">The stable, non-secret key identifier this provider reports.</param>
+    public FakeMasterKeyProvider(string kekId = "k1")
+    {
+        KekId = kekId;
+        _key = RandomNumberGenerator.GetBytes(32);
+    }
+
+    /// <summary>
+    /// Creates a provider that reuses an explicit 32-byte key. Use this to build a second
+    /// provider with the same key bytes as another (or, by omitting it, a different random key).
+    /// </summary>
+    /// <param name="kekId">The stable, non-secret key identifier this provider reports.</param>
+    /// <param name="key">The exact 32-byte master key material to use.</param>
+    public FakeMasterKeyProvider(string kekId, byte[] key)
+    {
+        KekId = kekId;
+        _key = (byte[])key.Clone();
+    }
+
+    /// <inheritdoc />
+    public string KekId { get; }
+
+    /// <inheritdoc />
+    public ReadOnlyMemory<byte> GetMasterKey() => _key;
+}