Setup

Sources/Packages/Package.swift

@@ -18,6 +18,9 @@ let package = Package(
         .library(
             name: "SmartCardSecretKit",
             targets: ["SmartCardSecretKit"]),
+        .library(
+            name: "ProxyAgentSecretKit",
+            targets: ["ProxyAgentSecretKit"]),
         .library(
             name: "SecretAgentKit",
             targets: ["SecretAgentKit"]),
@@ -47,6 +50,10 @@ let package = Package(
             name: "SmartCardSecretKit",
             dependencies: ["SecretKit"]
         ),
+        .target(
+            name: "ProxyAgentSecretKit",
+            dependencies: ["SecretKit", "SecretAgentKit"]
+        ),
         .target(
             name: "SecretAgentKit",
             dependencies: ["SecretKit", "SecretAgentKitHeaders"]

Sources/Packages/Sources/ProxyAgentSecretKit/ProxyAgent.swift

@@ -0,0 +1,2 @@
+/// Namespace for the Proxy Agent implementations.
+public enum ProxyAgent {}

Sources/Packages/Sources/ProxyAgentSecretKit/ProxyAgentSecret.swift

@@ -0,0 +1,19 @@
+import Foundation
+import Combine
+import SecretKit
+
+extension SmartCard {
+
+    /// An implementation of Secret backed by a Smart Card.
+    public struct Secret: SecretKit.Secret {
+
+        public let id: Data
+        public let name: String
+        public let algorithm: Algorithm
+        public let keySize: Int
+        public let requiresAuthentication: Bool = false
+        public let publicKey: Data
+
+    }
+
+}

Sources/Packages/Sources/ProxyAgentSecretKit/ProxyAgentStore.swift

@@ -0,0 +1,57 @@
+import Foundation
+import Security
+import CryptoTokenKit
+import LocalAuthentication
+import SecretKit
+
+extension ProxyAgent {
+
+    /// An implementation of Store backed by a Proxy Agent.
+    public class Store: SecretStore {
+
+        @Published public var isAvailable: Bool = false
+        public let id = UUID()
+        public private(set) var name = NSLocalizedString("Proxy SSH Agent", comment: "Proxy SSH Agent")
+        @Published public private(set) var secrets: [Secret] = []
+
+        /// Initializes a Store.
+        public init() {
+        }
+
+        // MARK: Public API
+
+        public func create(name: String) throws {
+            fatalError("Keys must be created on the smart card.")
+        }
+
+        public func delete(secret: Secret) throws {
+            fatalError("Keys must be deleted on the smart card.")
+        }
+
+        public func sign(data: Data, with secret: SecretType, for provenance: SigningRequestProvenance) throws -> Data {
+        }
+
+        public func existingPersistedAuthenticationContext(secret: ProxyAgent.Secret) -> PersistedAuthenticationContext? {
+            nil
+        }
+
+        public func persistAuthentication(secret: ProxyAgent.Secret, forDuration: TimeInterval) throws {
+        }
+
+    }
+
+}
+
+extension ProxyAgent.Store {
+
+}
+
+extension ProxyAgent {
+
+    /// A signing-related error.
+    public struct SigningError: Error {
+        /// The underlying error reported by the API, if one was returned.
+        public let error: SecurityError?
+    }
+
+}