5-improve-encrypted-storage (#6)

Added the use of DEK's for encryption of secrets. Both the KEK's and DEK's are stored in a way that you can have multiple key of which one is active. But the others are still available for decrypting. This allows for implementing key rotation.

Co-authored-by: eelke <eelke@eelkeklein.nl>
Co-authored-by: Eelke76 <31384324+Eelke76@users.noreply.github.com>
Reviewed-on: #6

IdentityShroud.Core/Contracts/IClientService.cs

@@ -0,0 +1,14 @@
+using IdentityShroud.Core.Model;
+
+namespace IdentityShroud.Core.Contracts;
+
+public interface IClientService
+{
+    Task<Result<Client>> Create(
+        Guid realmId,
+        ClientCreateRequest request, 
+        CancellationToken ct = default);
+
+    Task<Client?> GetByClientId(Guid realmId, string clientId, CancellationToken ct = default);
+    Task<Client?> FindById(Guid realmId, int id, CancellationToken ct = default);
+}

IdentityShroud.Core/Contracts/IClock.cs

@@ -0,0 +1,6 @@
+namespace IdentityShroud.Core.Contracts;
+
+public interface IClock
+{
+    DateTime UtcNow();
+}

IdentityShroud.Core/Contracts/IDataEncryptionService.cs

@@ -0,0 +1,9 @@
+using IdentityShroud.Core.Security;
+
+namespace IdentityShroud.Core.Contracts;
+
+public interface IDataEncryptionService
+{
+    EncryptedValue Encrypt(ReadOnlySpan<byte> plain);
+    byte[] Decrypt(EncryptedValue input);
+}

IdentityShroud.Core/Contracts/IDekEncryptionService.cs

@@ -0,0 +1,11 @@
+using IdentityShroud.Core.Security;
+
+namespace IdentityShroud.Core.Contracts;
+
+
+
+public interface IDekEncryptionService
+{
+    EncryptedDek Encrypt(ReadOnlySpan<byte> plain);
+    byte[] Decrypt(EncryptedDek input);
+}

IdentityShroud.Core/Contracts/IEncryptionService.cs

@@ -1,7 +0,0 @@
-namespace IdentityShroud.Core.Contracts;
-
-public interface IEncryptionService
-{
-    byte[] Encrypt(byte[] plain);
-    byte[] Decrypt(byte[] cipher);
-}

IdentityShroud.Core/Contracts/IKeyService.cs

@@ -0,0 +1,12 @@
+using IdentityShroud.Core.Messages;
+using IdentityShroud.Core.Model;
+using IdentityShroud.Core.Security.Keys;
+
+namespace IdentityShroud.Core.Contracts;
+
+public interface IKeyService
+{
+    RealmKey CreateKey(KeyPolicy policy);
+
+    JsonWebKey? CreateJsonWebKey(RealmKey realmKey);
+}

IdentityShroud.Core/Contracts/IRealmContext.cs

@@ -0,0 +1,9 @@
+using IdentityShroud.Core.Model;
+
+namespace IdentityShroud.Core.Contracts;
+
+public interface IRealmContext
+{
+    public Realm GetRealm();
+    Task<IList<RealmDek>> GetDeks(CancellationToken ct = default);
+}

IdentityShroud.Core/Contracts/IRealmService.cs

@@ -1,12 +1,15 @@
 using IdentityShroud.Core.Messages.Realm;
 using IdentityShroud.Core.Model;
+using IdentityShroud.Core.Services;
 
-namespace IdentityShroud.Core.Services;
+namespace IdentityShroud.Core.Contracts;
 
 public interface IRealmService
 {
+    Task<Realm?> FindById(Guid id, CancellationToken ct = default);
     Task<Realm?> FindBySlug(string slug, CancellationToken ct = default);
         
     Task<Result<RealmCreateResponse>> Create(RealmCreateRequest request, CancellationToken ct = default);
     Task LoadActiveKeys(Realm realm);
+    Task LoadDeks(Realm realm);
 }

IdentityShroud.Core/Contracts/ISecretProvider.cs

@@ -1,6 +1,14 @@
+using IdentityShroud.Core.Security;
+
 namespace IdentityShroud.Core.Contracts;
 
 public interface ISecretProvider
 {
     string GetSecret(string name);
+
+    /// <summary>
+    /// Should return one active key, might return inactive keys.
+    /// </summary>
+    /// <returns></returns>
+    KeyEncryptionKey[] GetKeys(string name);
 }

IdentityShroud.Core/DTO/Client/ClientCreateRequest.cs

@@ -0,0 +1,10 @@
+namespace IdentityShroud.Core.Contracts;
+
+public class ClientCreateRequest
+{
+    public required string ClientId { get; set; }
+    public string? Name { get; set; }
+    public string? Description { get; set; }
+    public string? SignatureAlgorithm { get; set; }
+    public bool? AllowClientCredentialsFlow { get; set; }
+}

IdentityShroud.Core/DTO/JsonWebKey.cs

@@ -0,0 +1,49 @@
+using System.Text.Json.Serialization;
+using IdentityShroud.Core.Helpers;
+
+namespace IdentityShroud.Core.Messages;
+
+// https://www.rfc-editor.org/rfc/rfc7517.html
+
+
+public class JsonWebKey
+{
+    [JsonPropertyName("kty")]
+    public string KeyType { get; set; } = "RSA";
+    
+    // Common values sig(nature) enc(ryption)
+    [JsonPropertyName("use")]
+    public string? Use { get; set; } = "sig"; // "sig" for signature, "enc" for encryption
+    
+    // Per standard this field is optional, commented out for now as it seems not 
+    // have any good use in an identity server. Anyone validating tokens should use
+    // the algorithm specified in the header of the token.
+    // [JsonPropertyName("alg")]
+    // public string? Algorithm { get; set; } = "RS256";
+    
+    [JsonPropertyName("kid")]
+    public required string KeyId { get; set; }
+    
+    // RSA Public Key Components
+    [JsonPropertyName("n")]
+    public string? Modulus { get; set; }
+    
+    [JsonPropertyName("e")]
+    public string? Exponent { get; set; }
+    
+    // ECdsa
+    public string? Curve { get; set; }
+    [JsonConverter(typeof(Base64UrlConverter))]
+    public byte[]? X { get; set; }
+    [JsonConverter(typeof(Base64UrlConverter))]
+    public byte[]? Y { get; set; }
+    
+    // Optional fields
+    // [JsonPropertyName("x5c")]
+    // [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    // public List<string>? X509CertificateChain { get; set; }
+    //
+    // [JsonPropertyName("x5t")]
+    // [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    // public string? X509CertificateThumbprint { get; set; }    
+}

IdentityShroud.Core/DTO/JsonWebKeySet.cs

@@ -0,0 +1,9 @@
+using System.Text.Json.Serialization;
+
+namespace IdentityShroud.Core.Messages;
+
+public class JsonWebKeySet
+{
+    [JsonPropertyName("keys")]
+    public List<JsonWebKey> Keys { get; set; } = new List<JsonWebKey>();
+}

IdentityShroud.Core/Db.cs

@@ -1,5 +1,7 @@
 using IdentityShroud.Core.Model;
+using IdentityShroud.Core.Security;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 
@@ -16,9 +18,44 @@ public class Db(
     ILoggerFactory? loggerFactory) 
     : DbContext
 {
+    public virtual DbSet<Client> Clients { get; set; }
     public virtual DbSet<Realm> Realms { get; set; }
-    public virtual DbSet<Key> Keys { get; set; }
-    
+    public virtual DbSet<RealmKey> Keys { get; set; }
+    public virtual DbSet<RealmDek> Deks { get; set; }
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        var dekIdConverter = new ValueConverter<DekId, Guid>(
+            id => id.Id,
+            guid => new DekId(guid));
+
+        var kekIdConverter = new ValueConverter<KekId, Guid>(
+            id => id.Id,
+            guid => new KekId(guid));
+
+        modelBuilder.Entity<RealmDek>()
+            .Property(d => d.Id)
+            .HasConversion(dekIdConverter);
+
+        modelBuilder.Entity<RealmDek>()
+            .OwnsOne(d => d.KeyData, keyData =>
+            {
+                keyData.Property(k => k.KekId).HasConversion(kekIdConverter);
+            });
+
+        modelBuilder.Entity<RealmKey>()
+            .OwnsOne(k => k.Key, key =>
+            {
+                key.Property(k => k.KekId).HasConversion(kekIdConverter);
+            });
+
+        modelBuilder.Entity<ClientSecret>()
+            .OwnsOne(c => c.Secret, secret =>
+            {
+                secret.Property(s => s.DekId).HasConversion(dekIdConverter);
+            });
+    }
+
     protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
     {
         optionsBuilder.UseNpgsql("<connection string>");

IdentityShroud.Core/Helpers/Base64UrlConverter.cs

@@ -0,0 +1,28 @@
+using System.Buffers;
+using System.Buffers.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace IdentityShroud.Core.Helpers;
+
+public class Base64UrlConverter : JsonConverter<byte[]>
+{
+    public override byte[] Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        // GetValueSpan gives you the raw UTF-8 bytes of the JSON string value
+        if (reader.HasValueSequence)
+        {
+            var valueSequence = reader.ValueSequence.ToArray();
+            return Base64Url.DecodeFromUtf8(valueSequence);
+        }
+        return Base64Url.DecodeFromUtf8(reader.ValueSpan);
+    }
+
+    public override void Write(Utf8JsonWriter writer, byte[] value, JsonSerializerOptions options)
+    {
+        int encodedLength = Base64Url.GetEncodedLength(value.Length);
+        Span<byte> buffer = encodedLength <= 256 ? stackalloc byte[encodedLength] : new byte[encodedLength];
+        Base64Url.EncodeToUtf8(value, buffer);
+        writer.WriteStringValue(buffer);
+    }
+}

IdentityShroud.Core/Helpers/SlugHelper.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Globalization;
 using System.Security.Cryptography;
 using System.Text;

IdentityShroud.Core/IdentityShroud.Core.csproj

@@ -11,7 +11,10 @@
       <PackageReference Include="FluentResults" Version="4.0.0" />
       <PackageReference Include="FluentValidation" Version="12.1.1" />
       <PackageReference Include="jose-jwt" Version="5.2.0" />
+      <PackageReference Include="LanguageExt.Core" Version="4.4.9" />
+      <PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" Version="2.3.9" />
       <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="10.0.2" />
+      <PackageReference Include="Microsoft.AspNetCore.WebUtilities" Version="10.0.2" />
       <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="10.0.0" />
     </ItemGroup>
     
@@ -19,10 +22,4 @@
         <Using Include="FluentResults" />
     </ItemGroup>
 
-    <ItemGroup>
-      <Reference Include="Microsoft.AspNetCore.WebUtilities">
-        <HintPath>..\..\..\.nuget\packages\microsoft.aspnetcore.webutilities\10.0.2\lib\net10.0\Microsoft.AspNetCore.WebUtilities.dll</HintPath>
-      </Reference>
-    </ItemGroup>
-
 </Project>

IdentityShroud.Core/Model/Client.cs

@@ -1,11 +1,29 @@
-using IdentityShroud.Core.Security;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using Microsoft.EntityFrameworkCore;
 
 namespace IdentityShroud.Core.Model;
 
+[Table("client")]
+[Index(nameof(ClientId), IsUnique = true)]
 public class Client
 {
-    public Guid Id { get; set; }
-    public string Name { get; set; }
+    [Key]
+    public int Id { get; set; }
+    public Guid RealmId { get; set; }
+    [MaxLength(40)]
+    public required string ClientId { get; set; }
+    [MaxLength(80)]
+    public string? Name { get; set; }
+    [MaxLength(2048)]
+    public string? Description { get; set; }
     
-    public string? SignatureAlgorithm { get; set; } = JsonWebAlgorithm.RS256;
+    [MaxLength(20)]
+    public string? SignatureAlgorithm { get; set; }
+    
+    public bool AllowClientCredentialsFlow { get; set; } = false;
+    
+    public required DateTime CreatedAt { get; set; }
+
+    public List<ClientSecret> Secrets { get; set; } = [];
 }

IdentityShroud.Core/Model/ClientSecret.cs

@@ -0,0 +1,17 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using IdentityShroud.Core.Contracts;
+using IdentityShroud.Core.Security;
+
+namespace IdentityShroud.Core.Model;
+
+[Table("client_secret")]
+public class ClientSecret
+{
+    [Key]
+    public int Id { get; set; }
+    public Guid ClientId { get; set; }
+    public DateTime CreatedAt { get; set; }
+    public DateTime? RevokedAt { get; set; }
+    public required EncryptedValue Secret { get; set; }
+}

IdentityShroud.Core/Model/Key.cs

@@ -1,45 +0,0 @@
-using System.ComponentModel.DataAnnotations.Schema;
-using IdentityShroud.Core.Contracts;
-
-namespace IdentityShroud.Core.Model;
-
-
-[Table("key")]
-public class Key
-{
-    private byte[] _privateKeyDecrypted = [];
-
-    public Guid Id { get; set; }
-    
-    public DateTime CreatedAt { get; set; }
-    public DateTime? DeactivatedAt { get; set; }
-
-    /// <summary>
-    /// Key with highest priority will be used. While there is not really a use case for this I know some users
-    /// are more comfortable replacing keys by using priority then directly deactivating the old key.
-    /// </summary>
-    public int Priority { get; set; } = 10;
-    
-    public byte[] PrivateKeyEncrypted
-    {
-        get;
-        set
-        {
-            field = value;
-            _privateKeyDecrypted = [];
-        }
-    } = [];
-
-    public byte[] GetPrivateKey(IEncryptionService encryptionService)
-    {
-        if (_privateKeyDecrypted.Length == 0 && PrivateKeyEncrypted.Length > 0)
-            _privateKeyDecrypted = encryptionService.Decrypt(PrivateKeyEncrypted);
-        return _privateKeyDecrypted;
-    }
-
-    public void SetPrivateKey(IEncryptionService encryptionService, byte[] privateKey)
-    {
-        PrivateKeyEncrypted = encryptionService.Encrypt(privateKey);
-        _privateKeyDecrypted = privateKey;
-    }
-}

IdentityShroud.Core/Model/Realm.cs

@@ -1,7 +1,6 @@
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
 using IdentityShroud.Core.Security;
-using Microsoft.EntityFrameworkCore;
 
 namespace IdentityShroud.Core.Model;
 
@@ -20,11 +19,22 @@ public class Realm
     public string Name { get; set; } = "";
     public List<Client> Clients { get; init; } = [];
 
-    public List<Key> Keys { get; init; } = [];
+    public List<RealmKey> Keys { get; init; } = [];
+
+    public List<RealmDek> Deks { get; init; } = [];
 
     /// <summary>
     /// Can be overriden per client
     /// </summary>
     public string DefaultSignatureAlgorithm { get; set; } = JsonWebAlgorithm.RS256;
-    
+}
+
+[Table("realm_dek")]
+public record RealmDek
+{
+    public required DekId Id { get; init; }
+    public required bool Active { get; set; }
+    public required string Algorithm { get; init; }
+    public required EncryptedDek KeyData { get; init; }
+    public required Guid RealmId { get; init; }
 }

IdentityShroud.Core/Model/RealmKey.cs

@@ -0,0 +1,27 @@
+using System.ComponentModel.DataAnnotations.Schema;
+using IdentityShroud.Core.Contracts;
+using IdentityShroud.Core.Security;
+using Microsoft.EntityFrameworkCore;
+
+namespace IdentityShroud.Core.Model;
+
+
+[Table("realm_key")]
+public record RealmKey
+{
+    public required Guid Id { get; init; }
+    public required string KeyType { get; init; }
+
+    
+    public required EncryptedDek Key { get; init; }
+    public required DateTime CreatedAt { get; init; }
+    public DateTime? RevokedAt { get; set; }
+
+    /// <summary>
+    /// Key with highest priority will be used. While there is not really a use case for this I know some users
+    /// are more comfortable replacing keys by using priority then directly deactivating the old key.
+    /// </summary>
+    public int Priority { get; set; } = 10;
+    
+
+}

IdentityShroud.Core/Security/AesGcmHelper.cs

@@ -1,71 +0,0 @@
-using System.Security.Cryptography;
-
-namespace IdentityShroud.Core.Security;
-
-public static class AesGcmHelper
-{
-    
-    public static byte[] EncryptAesGcm(byte[] plaintext, byte[] key)
-    {
-        int tagSize = AesGcm.TagByteSizes.MaxSize;
-        using var aes = new AesGcm(key, tagSize);
-        
-        Span<byte> nonce = stackalloc byte[AesGcm.NonceByteSizes.MaxSize];
-        RandomNumberGenerator.Fill(nonce);
-        Span<byte> ciphertext = stackalloc byte[plaintext.Length];
-        Span<byte> tag = stackalloc byte[tagSize];
-
-        aes.Encrypt(nonce, plaintext, ciphertext, tag);
-
-        // Return concatenated nonce|ciphertext|tag
-        var result = new byte[nonce.Length + ciphertext.Length + tag.Length];
-        nonce.CopyTo(result.AsSpan(0, nonce.Length));
-        ciphertext.CopyTo(result.AsSpan(nonce.Length, ciphertext.Length));
-        tag.CopyTo(result.AsSpan(nonce.Length + ciphertext.Length, tag.Length));
-        return result;
-    }
-    
-    // --------------------------------------------------------------------
-    // DecryptAesGcm
-    //   • key      – 32‑byte (256‑bit) secret key (same key used for encryption)
-    //   • payload  – byte[] containing nonce‖ciphertext‖tag
-    //   • returns  – the original plaintext bytes
-    // --------------------------------------------------------------------
-    public static byte[] DecryptAesGcm(byte[] payload, byte[] key)
-    {
-        if (payload == null) throw new ArgumentNullException(nameof(payload));
-        if (key == null)     throw new ArgumentNullException(nameof(key));
-        if (key.Length != 32) // 256‑bit key
-            throw new ArgumentException("Key must be 256 bits (32 bytes) for AES‑256‑GCM.", nameof(key));
-
-        // ----------------------------------------------------------------
-        // 1️⃣ Extract the three components.
-        // ----------------------------------------------------------------
-        // AesGcm.NonceByteSizes.MaxSize = 12 bytes (standard GCM nonce length)
-        // AesGcm.TagByteSizes.MaxSize   = 16 bytes (128‑bit authentication tag)
-        int nonceSize = AesGcm.NonceByteSizes.MaxSize; // 12
-        int tagSize   = AesGcm.TagByteSizes.MaxSize;   // 16
-
-        if (payload.Length < nonceSize + tagSize)
-            throw new ArgumentException("Payload is too short to contain nonce, ciphertext, and tag.", nameof(payload));
-
-        ReadOnlySpan<byte> nonce = new(payload, 0, nonceSize);
-        ReadOnlySpan<byte> ciphertext = new(payload, nonceSize, payload.Length - nonceSize - tagSize);
-        ReadOnlySpan<byte> tag = new(payload, payload.Length - tagSize, tagSize);
-
-        byte[] plaintext = new byte[ciphertext.Length];
-
-        using var aes = new AesGcm(key, tagSize);
-        try
-        {
-            aes.Decrypt(nonce, ciphertext, tag, plaintext);
-        }
-        catch (CryptographicException ex)
-        {
-            // Tag verification failed → tampering or wrong key/nonce.
-            throw new InvalidOperationException("Decryption failed – authentication tag mismatch.", ex);
-        }
-
-        return plaintext;
-    }
-}

IdentityShroud.Core/Security/ConfigurationSecretProvider.cs

@@ -14,4 +14,9 @@ public class ConfigurationSecretProvider(IConfiguration configuration) : ISecret
     {
         return secrets.GetValue<string>(name) ?? "";
     }
+
+    public KeyEncryptionKey[] GetKeys(string name)
+    {
+        return secrets.GetSection(name).Get<KeyEncryptionKey[]>() ?? [];
+    }
 }

IdentityShroud.Core/Security/DekId.cs

@@ -0,0 +1,6 @@
+namespace IdentityShroud.Core.Security;
+
+public record struct DekId(Guid Id)
+{
+    public static DekId NewId() => new(Guid.NewGuid());
+}

IdentityShroud.Core/Security/EncryptedDek.cs

@@ -0,0 +1,6 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace IdentityShroud.Core.Security;
+
+[Owned]
+public record EncryptedDek(KekId KekId, byte[] Value);

IdentityShroud.Core/Security/EncryptedValue.cs

@@ -0,0 +1,8 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace IdentityShroud.Core.Security;
+
+[Owned]
+public record EncryptedValue(DekId DekId, byte[] Value);
+
+

IdentityShroud.Core/Security/Encryption.cs

@@ -0,0 +1,70 @@
+using System.Security.Cryptography;
+
+namespace IdentityShroud.Core.Security;
+
+public static class Encryption
+{
+    private record struct AlgVersion(int Version, int NonceSize, int TagSize);
+
+    private static AlgVersion[] _versions = 
+    [
+        new(0, 0, 0), // version 0 does not realy exist
+        new(1, 12, 16), // version 1
+    ];
+    
+    public static byte[] Encrypt(ReadOnlySpan<byte> plaintext, ReadOnlySpan<byte> key)
+    {
+        const int versionNumber = 1; 
+        AlgVersion versionParams = _versions[versionNumber];
+
+        int resultSize = 1 + versionParams.NonceSize + versionParams.TagSize + plaintext.Length;
+        // allocate buffer for complete response 
+        var result = new byte[resultSize];
+        
+        result[0] = (byte)versionParams.Version;
+
+        // make the spans that point to the parts of the result where their data is located
+        var nonce = result.AsSpan(1, versionParams.NonceSize); 
+        var tag = result.AsSpan(1 + versionParams.NonceSize, versionParams.TagSize);
+        var cipher = result.AsSpan(1 + versionParams.NonceSize + versionParams.TagSize);
+
+        // use the spans to place the data directly in its place
+        RandomNumberGenerator.Fill(nonce);
+        using var aes = new AesGcm(key, versionParams.TagSize);
+        aes.Encrypt(nonce, plaintext, cipher, tag);
+        return result;
+    }
+    
+    public static byte[] Decrypt(ReadOnlyMemory<byte> input, ReadOnlySpan<byte> key)
+    {
+        var payload = input.Span;
+        int versionNumber = (int)payload[0];
+        if (versionNumber != 1)
+            throw new ArgumentException("Invalid payload");
+        
+        AlgVersion versionParams = _versions[versionNumber];
+        
+        
+        if (payload.Length < 1 + versionParams.NonceSize + versionParams.TagSize)
+            throw new ArgumentException("Payload is too short to contain nonce, ciphertext, and tag.", nameof(payload));
+
+        ReadOnlySpan<byte> nonce = payload.Slice(1, versionParams.NonceSize);
+        ReadOnlySpan<byte> tag = payload.Slice(1 + versionParams.NonceSize, versionParams.TagSize);
+        ReadOnlySpan<byte> cipher = payload.Slice(1 + versionParams.NonceSize + versionParams.TagSize);
+
+        byte[] plaintext = new byte[cipher.Length];
+
+        using var aes = new AesGcm(key, versionParams.TagSize);
+        try
+        {
+            aes.Decrypt(nonce, cipher, tag, plaintext);
+        }
+        catch (CryptographicException ex)
+        {
+            // Tag verification failed → tampering or wrong key/nonce.
+            throw new InvalidOperationException("Decryption failed – authentication tag mismatch.", ex);
+        }
+
+        return plaintext;
+    }
+}

IdentityShroud.Core/Security/JsonWebAlgorithm.cs

@@ -1,5 +1,3 @@
-using System.Security.Cryptography;
-
 namespace IdentityShroud.Core.Security;
 
 public static class JsonWebAlgorithm

IdentityShroud.Core/Security/KekId.cs

@@ -0,0 +1,41 @@
+using System.ComponentModel;
+using System.Globalization;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace IdentityShroud.Core.Security;
+
+[JsonConverter(typeof(KekIdJsonConverter))]
+[TypeConverter(typeof(KekIdTypeConverter))]
+public readonly record struct KekId
+{
+    public Guid Id { get; } 
+
+    public KekId(Guid id)
+    {
+        Id = id;
+    }
+
+    public static KekId NewId()
+    {
+        return new KekId(Guid.NewGuid());
+    }
+}
+
+public class KekIdJsonConverter : JsonConverter<KekId>
+{
+    public override KekId Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+        => new KekId(reader.GetGuid());
+
+    public override void Write(Utf8JsonWriter writer, KekId value, JsonSerializerOptions options)
+        => writer.WriteStringValue(value.Id);
+}
+
+public class KekIdTypeConverter : TypeConverter
+{
+    public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
+        => sourceType == typeof(string) || base.CanConvertFrom(context, sourceType);
+
+    public override object? ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
+        => value is string s ? new KekId(Guid.Parse(s)) : base.ConvertFrom(context, culture, value);
+}

IdentityShroud.Core/Security/KeyEncryptionKey.cs

@@ -0,0 +1,10 @@
+namespace IdentityShroud.Core.Security;
+
+/// <summary>
+/// Contains a KEK and associated relevant data. This structure
+/// </summary>
+/// <param name="Id"></param>
+/// <param name="Active"></param>
+/// <param name="Algorithm"></param>
+/// <param name="Key"></param>
+public record KeyEncryptionKey(KekId Id, bool Active, string Algorithm, byte[] Key);

IdentityShroud.Core/Security/Keys/IKeyProvider.cs

@@ -0,0 +1,19 @@
+using IdentityShroud.Core.Messages;
+
+namespace IdentityShroud.Core.Security.Keys;
+
+public abstract class KeyPolicy
+{
+    public abstract string KeyType { get; }
+}
+
+
+public interface IKeyProvider
+{
+    byte[] CreateKey(KeyPolicy policy);
+
+    void SetJwkParameters(byte[] key, JsonWebKey jwk);
+}
+
+
+

IdentityShroud.Core/Security/Keys/IKeyProviderFactory.cs

@@ -0,0 +1,7 @@
+namespace IdentityShroud.Core.Security.Keys;
+
+
+public interface IKeyProviderFactory
+{
+    public IKeyProvider CreateProvider(string keyType);
+}

IdentityShroud.Core/Security/Keys/KeyProviderFactory.cs

@@ -0,0 +1,17 @@
+using IdentityShroud.Core.Security.Keys.Rsa;
+
+namespace IdentityShroud.Core.Security.Keys;
+
+public class KeyProviderFactory : IKeyProviderFactory
+{
+    public IKeyProvider CreateProvider(string keyType)
+    {
+        switch (keyType)
+        {
+            case "RSA":
+                return new RsaProvider();
+            default:
+                throw new NotImplementedException();
+        }
+    }
+}

IdentityShroud.Core/Security/Keys/Rsa/RsaProvider.cs

@@ -0,0 +1,35 @@
+using System.Buffers.Text;
+using System.Security.Cryptography;
+using IdentityShroud.Core.Messages;
+
+namespace IdentityShroud.Core.Security.Keys.Rsa;
+
+public class RsaKeyPolicy : KeyPolicy
+{
+    public override string KeyType => "RSA";
+    public int KeySize { get; } = 2048;
+}
+
+public class RsaProvider : IKeyProvider
+{
+    public byte[] CreateKey(KeyPolicy policy)
+    {
+        if (policy is RsaKeyPolicy p)
+        {
+            using var rsa = RSA.Create(p.KeySize);
+            return rsa.ExportPkcs8PrivateKey();
+        }
+
+        throw new ArgumentException("Incorrect policy type", nameof(policy));
+    }
+
+    public void SetJwkParameters(byte[] key, JsonWebKey jwk)
+    {
+        using var rsa = RSA.Create();
+        rsa.ImportPkcs8PrivateKey(key, out _);
+        var parameters = rsa.ExportParameters(includePrivateParameters: false);
+
+        jwk.Exponent = Base64Url.EncodeToString(parameters.Exponent);
+        jwk.Modulus = Base64Url.EncodeToString(parameters.Modulus);
+    }
+}

IdentityShroud.Core/Security/RsaHelper.cs

@@ -1,16 +0,0 @@
-using System.Security.Cryptography;
-
-namespace IdentityShroud.Core.Security;
-
-public static class RsaHelper
-{
-    /// <summary>
-    /// Load RSA private key from PKCS#8 format
-    /// </summary>
-    public static RSA LoadFromPkcs8(byte[] pkcs8Key)
-    {
-        var rsa = RSA.Create();
-        rsa.ImportPkcs8PrivateKey(pkcs8Key, out _);
-        return rsa;
-    }
-}

IdentityShroud.Core/Services/ClientService.cs

@@ -0,0 +1,65 @@
+using System.Security.Cryptography;
+using IdentityShroud.Core.Contracts;
+using IdentityShroud.Core.Model;
+using Microsoft.EntityFrameworkCore;
+
+namespace IdentityShroud.Core.Services;
+
+public class ClientService(
+    Db db,
+    IDataEncryptionService cryptor,
+    IClock clock) : IClientService
+{
+    public async Task<Result<Client>> Create(Guid realmId, ClientCreateRequest request, CancellationToken ct = default)
+    {
+        Client client = new()
+        {
+            RealmId = realmId,
+            ClientId = request.ClientId,
+            Name = request.Name,
+            Description = request.Description,
+            SignatureAlgorithm = request.SignatureAlgorithm,
+            AllowClientCredentialsFlow = request.AllowClientCredentialsFlow ?? false,
+            CreatedAt = clock.UtcNow(),
+        };
+        
+        if (client.AllowClientCredentialsFlow)
+        {
+            client.Secrets.Add(CreateSecret());
+        }
+
+        await db.AddAsync(client, ct);
+        await db.SaveChangesAsync(ct);
+
+        return client;
+    }
+
+    public async Task<Client?> GetByClientId(
+        Guid realmId,
+        string clientId, 
+        CancellationToken ct = default)
+    {
+        return await db.Clients.FirstOrDefaultAsync(c => c.ClientId == clientId && c.RealmId == realmId, ct);
+    }
+
+    public async Task<Client?> FindById(
+        Guid realmId,
+        int id, 
+        CancellationToken ct = default)
+    {
+        return await db.Clients.FirstOrDefaultAsync(c => c.Id == id && c.RealmId == realmId, ct);
+    }
+
+    private ClientSecret CreateSecret()
+    {
+        Span<byte> secret = stackalloc byte[24];
+        RandomNumberGenerator.Fill(secret);
+
+        return new ClientSecret()
+        {
+            CreatedAt = clock.UtcNow(),
+            Secret = cryptor.Encrypt(secret.ToArray()),
+        };
+
+    }
+}

IdentityShroud.Core/Services/ClockService.cs

@@ -0,0 +1,11 @@
+using IdentityShroud.Core.Contracts;
+
+namespace IdentityShroud.Core.Services;
+
+public class ClockService : IClock
+{
+    public DateTime UtcNow()
+    {
+        return DateTime.UtcNow;
+    }
+}

IdentityShroud.Core/Services/DataEncryptionService.cs

@@ -0,0 +1,41 @@
+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(ReadOnlySpan<byte> plain)
+    {
+        var dek = GetActiveDek();
+        var key = dekCryptor.Decrypt(dek.KeyData);
+        byte[] cipher = Encryption.Encrypt(plain, key);
+        return new (dek.Id, cipher);
+    }
+}

IdentityShroud.Core/Services/DekEncryptionService.cs

@@ -0,0 +1,38 @@
+using IdentityShroud.Core.Contracts;
+using IdentityShroud.Core.Security;
+
+namespace IdentityShroud.Core.Services;
+
+/// <summary>
+/// 
+/// </summary>
+public class DekEncryptionService : IDekEncryptionService
+{
+    // 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 readonly KeyEncryptionKey[] _encryptionKeys;
+
+    private KeyEncryptionKey ActiveKey => _encryptionKeys.Single(k => k.Active);
+    private KeyEncryptionKey GetKey(KekId keyId) => _encryptionKeys.Single(k => k.Id == keyId);
+
+    public DekEncryptionService(ISecretProvider secretProvider)
+    {
+        _encryptionKeys = secretProvider.GetKeys("master");
+        // if (_encryptionKey.Length != 32) // 256‑bit key
+        //     throw new Exception("Key must be 256 bits (32 bytes) for AES‑256‑GCM.");
+    }
+
+    public EncryptedDek Encrypt(ReadOnlySpan<byte> plaintext)
+    {
+        var encryptionKey = ActiveKey;
+        byte[] cipher = Encryption.Encrypt(plaintext, encryptionKey.Key);
+        return new (encryptionKey.Id, cipher);
+    }
+
+    public byte[] Decrypt(EncryptedDek input)
+    {
+        var encryptionKey = GetKey(input.KekId);
+
+        return Encryption.Decrypt(input.Value, encryptionKey.Key);
+    }
+}

IdentityShroud.Core/Services/EncryptionService.cs

@@ -1,27 +0,0 @@
-using IdentityShroud.Core.Contracts;
-using IdentityShroud.Core.Security;
-
-namespace IdentityShroud.Core.Services;
-
-/// <summary>
-/// 
-/// </summary>
-public class EncryptionService : IEncryptionService
-{
-    private readonly byte[] encryptionKey;
-
-    public EncryptionService(ISecretProvider secretProvider)
-    {
-        encryptionKey = Convert.FromBase64String(secretProvider.GetSecret("Master"));
-    }
-
-    public byte[] Encrypt(byte[] plain)
-    {
-        return AesGcmHelper.EncryptAesGcm(plain, encryptionKey);
-    }
-
-    public byte[] Decrypt(byte[] cipher)
-    {
-        return AesGcmHelper.DecryptAesGcm(cipher, encryptionKey);
-    }
-}

IdentityShroud.Core/Services/KeyService.cs

@@ -0,0 +1,46 @@
+using IdentityShroud.Core.Contracts;
+using IdentityShroud.Core.Messages;
+using IdentityShroud.Core.Model;
+using IdentityShroud.Core.Security.Keys;
+
+namespace IdentityShroud.Core.Services;
+
+public class KeyService(
+    IDekEncryptionService cryptor,
+    IKeyProviderFactory keyProviderFactory,
+    IClock clock) : IKeyService
+{
+    public RealmKey CreateKey(KeyPolicy policy)
+    {
+        IKeyProvider provider = keyProviderFactory.CreateProvider(policy.KeyType);
+        var plainKey = provider.CreateKey(policy);
+
+        return CreateKey(policy.KeyType, plainKey);
+    }
+
+    public JsonWebKey? CreateJsonWebKey(RealmKey realmKey)
+    {
+        JsonWebKey jwk = new()
+        {
+            KeyId = realmKey.Id.ToString(),
+            KeyType = realmKey.KeyType,
+            Use = "sig",
+        };
+        
+        IKeyProvider provider = keyProviderFactory.CreateProvider(realmKey.KeyType);
+        provider.SetJwkParameters(
+            cryptor.Decrypt(realmKey.Key),
+            jwk);
+
+        return jwk;
+    }
+
+    private RealmKey CreateKey(string keyType, byte[] plainKey) =>
+        new RealmKey()
+            {
+                Id = Guid.NewGuid(),
+                KeyType = keyType,
+                Key = cryptor.Encrypt(plainKey),
+                CreatedAt = clock.UtcNow(),
+            };
+}

IdentityShroud.Core/Services/RealmContext.cs

@@ -0,0 +1,26 @@
+using IdentityShroud.Core.Contracts;
+using IdentityShroud.Core.Model;
+using Microsoft.AspNetCore.Http;
+
+namespace IdentityShroud.Core.Services;
+
+public class RealmContext(
+    IHttpContextAccessor accessor,
+    IRealmService realmService) : IRealmContext
+{
+    public Realm GetRealm()
+    {
+        return (Realm)accessor.HttpContext.Items["RealmEntity"];
+    }
+
+    public async Task<IList<RealmDek>> GetDeks(CancellationToken ct = default)
+    {
+        Realm realm = GetRealm();
+        if (realm.Deks.Count == 0)
+        {
+            await realmService.LoadDeks(realm);
+        }
+
+        return realm.Deks;
+    }
+}

IdentityShroud.Core/Services/RealmService.cs

@@ -1,8 +1,9 @@
-using System.Security.Cryptography;
 using IdentityShroud.Core.Contracts;
 using IdentityShroud.Core.Helpers;
 using IdentityShroud.Core.Messages.Realm;
 using IdentityShroud.Core.Model;
+using IdentityShroud.Core.Security.Keys;
+using IdentityShroud.Core.Security.Keys.Rsa;
 using Microsoft.EntityFrameworkCore;
 
 namespace IdentityShroud.Core.Services;
@@ -11,8 +12,14 @@ public record RealmCreateResponse(Guid Id, string Slug, string Name);
 
 public class RealmService(
     Db db,
-    IEncryptionService encryptionService) : IRealmService
+    IKeyService keyService) : IRealmService
 {
+    public async Task<Realm?> FindById(Guid id, CancellationToken ct = default)
+    {
+        return await db.Realms
+            .SingleOrDefaultAsync(r => r.Id == id, ct);
+    }
+
     public async Task<Realm?> FindBySlug(string slug, CancellationToken ct = default)
     {
         return await db.Realms
@@ -26,8 +33,9 @@ public class RealmService(
             Id = request.Id ?? Guid.CreateVersion7(),
             Slug = request.Slug ?? SlugHelper.GenerateSlug(request.Name),
             Name = request.Name,
-            Keys = [ CreateKey() ],
         };
+        
+        realm.Keys.Add(keyService.CreateKey(GetKeyPolicy(realm)));
 
         db.Add(realm);
         await db.SaveChangesAsync(ct);
@@ -36,25 +44,26 @@ public class RealmService(
             realm.Id, realm.Slug, realm.Name);
     }
 
+    /// <summary>
+    /// Place holder for getting policies from the realm and falling back to sane defaults when no policies have been set.
+    /// </summary>
+    /// <param name="_"></param>
+    /// <returns></returns>
+    private KeyPolicy GetKeyPolicy(Realm _) => new RsaKeyPolicy();
+    
+
     public async Task LoadActiveKeys(Realm realm)
     {
         await db.Entry(realm).Collection(r => r.Keys)
             .Query()
-            .Where(k => k.DeactivatedAt == null)
+            .Where(k => k.RevokedAt == null)
             .LoadAsync();
-        
     }
 
-    private Key CreateKey()
+    public async Task LoadDeks(Realm realm)
     {
-        using RSA rsa = RSA.Create(2048);
-
-        Key key = new()
-        {
-            Priority = 10,
-        };
-        key.SetPrivateKey(encryptionService, rsa.ExportPkcs8PrivateKey());
-
-        return key;
+        await db.Entry(realm).Collection(r => r.Deks)
+            .Query()
+            .LoadAsync();
     }
 }