Encrypt realm data with dek which is encrypted with kek. The signing keys are also encrypted with the kek.

IdentityShroud.Core/Services/DataEncryptionService.cs

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+using IdentityShroud.Core.Contracts;
+using IdentityShroud.Core.Model;
+using IdentityShroud.Core.Security;
+
+namespace IdentityShroud.Core.Services;
+
+public class DataEncryptionService(
+    IRealmContext realmContext,
+    IDekEncryptionService dekCryptor) : IDataEncryptionService
+{
+    
+    // Note this array is expected to have one item in it most of the during key rotation it will have two
+    // until it is ensured the old key can safely be removed. More then two will work but is not really expected.
+    private IList<RealmDek>? _deks = null;
+
+    private IList<RealmDek> GetDeks()
+    {
+        if (_deks is null)
+            _deks = realmContext.GetDeks().Result;
+
+        return _deks;
+    }
+
+    private RealmDek GetActiveDek() => GetDeks().Single(d => d.Active);
+    private RealmDek GetKey(DekId id) => GetDeks().Single(d => d.Id == id);
+    
+    public byte[] Decrypt(EncryptedValue input)
+    {
+        var dek = GetKey(input.DekId);
+        var key = dekCryptor.Decrypt(dek.KeyData);
+        return Encryption.Decrypt(input.Value, key);
+    }
+
+    public EncryptedValue Encrypt(ReadOnlyMemory<byte> plain)
+    {
+        var dek = GetActiveDek();
+        var key = dekCryptor.Decrypt(dek.KeyData);
+        byte[] cipher = Encryption.Encrypt(plain, key);
+        return new (dek.Id, cipher);
+    }
+}