CryptoPassphrase  Check-in [496f11bd4b]

            let keyFilePath =
                documentDirectory.ofObject.appending(keyFile.ofObject)
            generator.keyFile = OFMutableData(contentsOfFile: keyFilePath)
        }

        let passphraseText = (passphraseField?.text ?? "") as NSString
        let passphrase = of_strdup(passphraseText.utf8String!)!
        generator.passphrase = UnsafePointer<CChar>(passphrase)
        let passphraseLen =
            passphraseText.lengthOfBytes(using: String.Encoding.utf8.rawValue)
        let passphrase = OFSecureData(count: passphraseLen,
                                      allowsSwappableMemory: false)
        memcpy(passphrase.mutableItems, passphraseText.utf8String!,
               passphraseLen)
        generator.passphrase = passphrase

        let mainStoryboard = UIStoryboard(name: "Main", bundle: nil)
        let activityController = mainStoryboard.instantiateViewController(
            withIdentifier: "activityIndicator")
        navigationController?.view.addSubview(activityController.view)

        DispatchQueue.global(qos: .default).async {
            OFException.try({
                generator.derivePassword()
            generator.derivePassword()
            }, finally: {
                if let keyFile = generator.keyFile as? OFMutableData {
                    of_explicit_memset(keyFile.mutableItems, 0, keyFile.count)
                }
        }

                of_explicit_memset(passphrase, 0, strlen(passphrase))
                free(passphrase)
            })
        }

        let password = NSMutableString(bytes: generator.output,
        let password = NSMutableString(bytes: generator.output.items,
                                       length: generator.length,
                                       encoding: String.Encoding.utf8.rawValue)!
        of_explicit_memset(generator.output, 0, generator.length)

        DispatchQueue.main.sync {
            activityController.view.isHidden = true
            block(password)
        }
    }