Our release of Silent Text 2.0 (ST-2) is a major rewrite of our previous product and harbinger of some of the technology that Silent Circle will be using to improve the security and refine the user experience of our customers. We have learned quite a bit about how our customers use messaging over mobile devices and have rolled much of their feedback into this release.
The primary impetus behind ST-2 was to address the following:
Eliminate the keying delay.
The prevailing end to end security algorithms were designed with the assumption that both parties are concurrently present on the network. This isn’t often the case for mobile devices. Ideally you should be able to start sending secure messages without waiting for the recipient to respond, but without sacrificing the same level of security and end to end encryption provided by the key exchange that we employ our current product.
To this end we have invented Progressive Encryption technology, a hybrid of both public key and ephemeral key agreement protocols. The SCIMP protocol used by Silent Text 2 incorporates this technology, enabling the sender to securely transport messages on the first packet and simultaneously transition to hash-committed Diffie-Hellman. All without the annoying push notifications for keying events.
Better security for data at rest.
The iOS implementation has been substantially rewritten. We walked away from Apple’s CoreData and didn’t look back. We replaced it with YapDatabase, developed by our own very talented Robbie Hanson. This gave us amazing improvements in performance and reliability as well as substantially better anti-forensics on the data at rest. All the protocol security in the world won’t help you if your device is not well protected and so we treat that with the same amount of concern. Robbie also wrote the XMPP Framework used by us, and it would seem by many other IOS messaging apps.
Improvements in user experience.
We have come a long way here, too. On Silent Text iOS we have done a major redesign of the user experience to improve the standards of secure mobile messaging. You will find a plethora of new features not the least of which is a native iPad split screen experience as well as Silent Contacts; a built-in secure contacts book. Other highlights include: messages can be queued while offline and sent later. Return receipts for messages, which can be turned off on a per conversation basis. There is also a secure media shelf to keep track of items such as documents and photos that are enclosed in the messages.
We have a number of things in the works across all of our platforms in the near future. Expect to see secure group conversations, as well as major improvements in cloud storage management. We have come a long way in the last two years and I believe you will be happy with where we are going.