Add key rotation and deletion methods to KeyManagementService (#14)

Sources/VaporOAuth/Protocols/KeyManagementService.swift

@@ -1,13 +1,60 @@
 import Foundation
 import JWTKit
 
+public enum KeyType: String, Codable {
+    case `public`
+    case `private`
+}
+
+/// Protocol for managing RSA keys used in cryptographic operations.
 public protocol KeyManagementService: Sendable  {
+
+    /// Generates a new RSA key.
+    /// - Returns: A newly generated RSAKey.
+    /// - Throws: An error if the key generation fails.
     func generateKey() throws -> RSAKey
+
+    /// Stores a RSA key.
+    /// - Parameter key: The RSAKey to be stored.
+    /// - Throws: An error if storing the key fails.
     func storeKey(_ key: RSAKey) throws
-    func retrieveKey(identifier: String) throws -> RSAKey
+
+    /// Retrieves a RSA key based on its identifier and type.
+    /// - Parameters:
+    ///   - identifier: The unique identifier of the key.
+    ///   - keyType: The type of key (public or private).
+    /// - Returns: The requested RSAKey.
+    /// - Throws: An error if retrieving the key fails.
+    func retrieveKey(identifier: String, keyType: KeyType) throws -> RSAKey
+
+    /// Retrieves the identifier of the public key.
+    /// - Returns: The identifier of the public key.
+    /// - Throws: An error if the operation fails.
     func publicKeyIdentifier() throws -> String
+
+    /// Converts a RSAKey to a JSON Web Key (JWK) format.
+    /// - Parameter key: The RSAKey to convert.
+    /// - Returns: The corresponding JWK.
+    /// - Throws: An error if the conversion fails.
     func convertToJWK(_ key: RSAKey) throws -> JWK 
+
+    /// Retrieves the identifier of the private key.
+    /// - Returns: The identifier of the private key.
+    /// - Throws: An error if the operation fails.
     func privateKeyIdentifier() throws -> String
-    // Additional methods for key rotation, deletion, etc.
 
-}
+    /// Rotates the keys by generating a new key and optionally deprecating the old one.
+    /// - Parameter deprecateOld: A boolean indicating whether to deprecate the old key.
+    /// - Throws: An error if the key rotation fails.
+    func rotateKey(deprecateOld: Bool) throws
+
+    /// Deletes a RSA key based on its identifier.
+    /// - Parameter identifier: The unique identifier of the key to be deleted.
+    /// - Throws: An error if the deletion fails.
+    func deleteKey(identifier: String) throws
+
+    /// Lists all available RSA keys.
+    /// - Returns: An array of identifiers of the available RSA keys.
+    /// - Throws: An error if the operation fails.
+    func listKeys() throws -> [String]
+}