To date we have built and run debug versions of our apps. Android Studio transparently manages the signing of these apps using auto-generated debug keys. This process will not suffice should we wish to publish to the Google Playstore. Here we examine how to prepare our app for release which entails generating and storing keys and signing the app. We then dig a little deeper and examine the cryptograpic technologies that support these actions.

We conclude our discussion on app signing with a very brief examination of the underlying mathematics used in basic cryptographic functions such as symmetric key and public key cryptography. Simple examples are provided to demonstrate Diffie-Hellman key exchange and RSA (public key cryptography).

Cryptography supports the millions of daily secure internet transactions, for example, in the use of HTTPS, SSH, secure email, secure messaging and eCommerce.