refactor PasswordEntitiy model, add decrypt extension

pass/Password.swift

@@ -0,0 +1,38 @@
+//
+//  Password.swift
+//  pass
+//
+//  Created by Mingshen Sun on 2/2/2017.
+//  Copyright © 2017 Bob Sun. All rights reserved.
+//
+
+import Foundation
+import SwiftyUserDefaults
+
+class Password {
+    var name = ""
+    var password = ""
+    var additions: [String: String]?
+    
+    init(name: String, password: String, additions: [String: String]?) {
+        self.name = name
+        self.password = password
+        self.additions = additions
+    }
+}
+
+extension PasswordEntity {
+    func decrypt() -> Password? {
+        var password: Password?
+        let encryptedDataPath = URL(fileURLWithPath: "\(Globals.shared.documentPath)/\(rawPath!)")
+        do {
+            let encryptedData = try Data(contentsOf: encryptedDataPath)
+            let decryptedData = try PasswordStore.shared.pgp.decryptData(encryptedData, passphrase: Defaults[.pgpKeyPassphrase])
+            let plain = String(data: decryptedData, encoding: .ascii) ?? ""
+            password = Password(name: name!, password: plain, additions: nil)
+        }  catch let error as NSError {
+            print(error.debugDescription)
+        }
+        return password
+    }
+}