feat: unify device auth + pairing

apps/macos/Sources/Clawdbot/DeviceIdentity.swift

@@ -0,0 +1,84 @@
+import CryptoKit
+import Foundation
+
+struct DeviceIdentity: Codable, Sendable {
+    var deviceId: String
+    var publicKey: String
+    var privateKey: String
+    var createdAtMs: Int
+}
+
+enum DeviceIdentityStore {
+    private static let fileName = "device.json"
+
+    static func loadOrCreate() -> DeviceIdentity {
+        let url = self.fileURL()
+        if let data = try? Data(contentsOf: url),
+           let decoded = try? JSONDecoder().decode(DeviceIdentity.self, from: data),
+           !decoded.deviceId.isEmpty,
+           !decoded.publicKey.isEmpty,
+           !decoded.privateKey.isEmpty {
+            return decoded
+        }
+        let identity = self.generate()
+        self.save(identity)
+        return identity
+    }
+
+    static func signPayload(_ payload: String, identity: DeviceIdentity) -> String? {
+        guard let privateKeyData = Data(base64Encoded: identity.privateKey) else { return nil }
+        do {
+            let privateKey = try Curve25519.Signing.PrivateKey(rawRepresentation: privateKeyData)
+            let signature = try privateKey.signature(for: Data(payload.utf8))
+            return self.base64UrlEncode(signature)
+        } catch {
+            return nil
+        }
+    }
+
+    private static func generate() -> DeviceIdentity {
+        let privateKey = Curve25519.Signing.PrivateKey()
+        let publicKey = privateKey.publicKey
+        let publicKeyData = publicKey.rawRepresentation
+        let privateKeyData = privateKey.rawRepresentation
+        let deviceId = SHA256.hash(data: publicKeyData).compactMap { String(format: "%02x", $0) }.joined()
+        return DeviceIdentity(
+            deviceId: deviceId,
+            publicKey: publicKeyData.base64EncodedString(),
+            privateKey: privateKeyData.base64EncodedString(),
+            createdAtMs: Int(Date().timeIntervalSince1970 * 1000))
+    }
+
+    private static func base64UrlEncode(_ data: Data) -> String {
+        let base64 = data.base64EncodedString()
+        return base64
+            .replacingOccurrences(of: "+", with: "-")
+            .replacingOccurrences(of: "/", with: "_")
+            .replacingOccurrences(of: "=", with: "")
+    }
+
+    static func publicKeyBase64Url(_ identity: DeviceIdentity) -> String? {
+        guard let data = Data(base64Encoded: identity.publicKey) else { return nil }
+        return self.base64UrlEncode(data)
+    }
+
+    private static func save(_ identity: DeviceIdentity) {
+        let url = self.fileURL()
+        do {
+            try FileManager.default.createDirectory(
+                at: url.deletingLastPathComponent(),
+                withIntermediateDirectories: true)
+            let data = try JSONEncoder().encode(identity)
+            try data.write(to: url, options: [.atomic])
+        } catch {
+            // best-effort only
+        }
+    }
+
+    private static func fileURL() -> URL {
+        let base = ClawdbotPaths.stateDirURL
+        return base
+            .appendingPathComponent("identity", isDirectory: true)
+            .appendingPathComponent(fileName, isDirectory: false)
+    }
+}