When you are feeling paranoid, PassLok's got you covered. A complete crypto toolkit that fits in 0.3MB, PassLok sits alongside your favorite email or texting app to lock and unlock messages with utmost security.
The basic function of PassLok is to lock text and files by putting somebody’s personal Lock on it, so that only that person may be able to unlock it with his/her matching Key.
Your Key is a short piece of text that you type into PassLok in order to unlock data meant for you. PassLok places no restrictions on your Key, but compensates for weak Keys transparently. From your Key, which is to remain in your head and never revealed to anyone else, PassLok makes a matching Lock, which you want to distribute widely. It doesn’t matter if your Lock falls into the wrong hands because it is impossible to get the Key from the Lock.
Another way to understand a Lock is as a longish phone number, which you give to anyone you wish to call you back. PassLok can make your Lock available to anyone who wants it if you so desire, but the default action is to leave Lock distribution completely up to you. You can email your Lock to your friends, along with a short set of instructions on how to make their own Locks, just by clicking one button.
Version 2.1, just released, adds the ability to make secure video chat invitations (sadly, not joinable within iOS, but at least you can start the chats), that people can join in a computer or Android device. Communication is direct between devices, without servers seeing any of the conversation.
Another first in v2.1 is read-once mode. The keys needed to decrypt read-once messages are overwritten during unlocking, and there are no backups. There is no server involved that might keep a copy.
PassLok puts a lot of power (AES-256, 521-bit elliptic curves, and more) under a simple interface, featuring a Learn mode and a comprehensive help system.
Last updated 6 Aug 2015