Parity Signer is a mobile application that allows any smartphone to act as an air-gapped crypto wallet. This is also known as "cold storage".

Once the app has been installed, users can create Ethereum accounts, sign messages/transactions, and transfer funds to and from these accounts without any sort of connectivity enabled on the device.

Users can opt to shut off and even physically remove the smartphone's Wifi, Mobile Network, and Bluetooth to ensure that the mobile phone containing these accounts will not be exposed to any online threat.

Disabling the mobile phone's networking abilities is a requirement for the app to be used as intended.

Have a look at the tutorial on our wiki to learn how to use Parity Signer together with Fether or MyCrypto app.

Any data transfer from or to the app will happen using QR code scanning. By doing so, the most sensitive piece of information, the private keys, will never leave the phone. The Parity Signer mobile app can be used to store any Ethereum account, this includes ETH, ETC as well as Ether from various testnets (Kovan, Ropsten...).

Parity Signer was built to be used offline. The mobile device used to run the app will hold valuable information that needs to be kept securely stored. It is therefore advised to:

• Get a separate mobile device.
• Make a factory reset.
• Enable full-disk encryption on the device, with a reasonable password (might not be on by default, for example for older Android devices).
• Do not use any kind of biometrics such as fingerprint or face recognition for device decryption/unlocking, as those may be less secure than regular passwords.
• Once the app has been installed, enable airplane mode and make sure to switch off Wifi, Bluetooth or any connection ability of the device.
• Only charge the phone on a power outlet that is never connected to the internet. Only charge the phone with the manufacturer's charging adapter. Do not charge the phone on public USB chargers.

• node.js (tested on v8.4.0)
• yarn (tested on 1.6.0)
• rustup (tested on rustup 1.16.0)
• rustc (tested on rustc 1.32.0 (9fda7c223 2019-01-16))
• cargo (tested on cargo 1.32.0 (8610973aa 2019-01-02))
• android_ndk (tested on r19)
• Android Studio (only for Android, tested on Version 3.3)
• Xcode (only for iOS, tested on Version 9.4.1 (9F2000))
• $NDK_HOME envarionment variable set to ndk home directory (eg. /usr/local/opt/android-ndk)
• $JAVA_HOME envarionment variable set to java home directory (eg. /Library/Java/JavaVirtualMachines/jdk1.8.0_60.jdk/Contents/Home)
• $ANDROID_HOME environment variable set to Android SDK directory (eg. /home/your_username/Android/Sdk)*.

* It's recommended to install Android Studio and use that to install the necessary build tools and SDKs for the Android version you want to test on. It's also the best way to test in the emulator. DO NOT INSTALL NDK VIA ANDROID STUDIO as that will install the latest version. Make sure to get r19 instead.

• macOS

  ./setup_macos.sh
  
  echo "ndk.dir=$NDK_HOME" > android/local.properties
  echo "sdk.dir=$ANDROID_HOME" >> android/local.properties
  

• linux

  ./setup_linux.sh
  
  echo "ndk.dir=$NDK_HOME" > android/local.properties
  echo "sdk.dir=$ANDROID_HOME" >> android/local.properties
  

• iOS

  npm run ios
  

• Android

  npm run android
  

For a quick test and to avoid the hurdle of creating an account, sending funds to it and finally create a transaction as described in the Parity Fether Tutorial, you can use a pre-funded account on Kovan Network. To get access to this account, you need to:

• Recover an account
• Select Kovan network and choose a name
• Use the recovery phrase: this is sparta you'll get the account address: 006E27B6A72E1f34C626762F3C4761547Aff1421
• Validate and accept the warning message
• Chose a pin code
• Scan this QR code to sign a transaction sending some Kovan Eth to the same account.

Corresponding data:

{
    "action": "signTransaction",
    "data": {
        "account": "006e27b6a72e1f34c626762f3c4761547aff1421",
        "rlp": "ea1584ee6b280082520894006e27b6a72e1f34c626762f3c4761547aff1421872386f26fc10000802a8080"
    }
}

This error should be accompanied with error: closed in terminal when deploying the debug version of the signer on a device that runs Android older than 5.0. It happens because the Android API does not support the reverse proxy that would allow the phone to communicate with the debug server on your computer.

A suitable workaround is to run both devices on the same WiFi and use your local WiFi IP address. Check your WiFi settings for your local IP address (eg. 192.168.1.42), then, while having the app open on the phone (either on error page or blank screen) run a command in terminal:

adb shell input keyevent 82

(You can find adb binary in your local Android SDK folder under platform-tools, eg. /home/your_username/Android/Sdk/platform-tools)

This should open a menu on the device. In that menu go to Dev Settings > Debug server host & port for device, and enter your local IP address with port 8081 (eg. 192.168.1.42:8081). Restart the app, the error should disappear.

1. Download NDK r19, unpack it in a convenient location.
2. Update your NDK_HOME env variable to the absolute path of the NDK directory.
3. Edit ./android/local.properties so that ndk.dir points to the absolute path to the NDK directory.
4. Remove old NDK build with rm -rf ./NDK.
5. Build the new NDK with ./create-ndk-standalone.sh.