Signal - the World's Most Secure Messaging App

Signal is a messaging app for Androids and iOS devices. It is widely hailed as the most secure such app available. It uses the ZRTP protocol (Zimmerman Real-Time Transfer Protocol) that reports indicate even the NSA can't crack. Edward Snowden uses the app regularly, and so do members of Congress.

Signal can be used for secure messages, phone calls, and video calls. After installing the app, you enter your phone number, and then submit a verification code.

You can adjust the Privacy Settings so that your IP address is never revealed to the people you are contacting, and prevent signal calls from being listed in your phone call history.

The app also allows user to guard against man in the middle attacks by comparing QR codes. The keys used to encrypt messages are stored on each Signal user's phone.

AES Crypt

AES Crypt is free file encryption software you can download at https://www.aescrypt.com/download/. AES Crypt allows you to right click on any file, and enter a password that will encrypt the file.

If a recipient of the file also has AES Crypt installed, they'll be able to open with the encrypted file with the right password. The encrypted file will be extracted to the same folder in which the .aes file to located so long as a file the same name does not already exist in that folder.

On the same web page you can download the console version of AES Crypt, which is a single file, aescrypt.exe in a zip file. If you put this file in a folder with multiple files and run these commands in a batch file:

aescrypt -e -p abc^^123 C:\FooFolder2\Book1.pdf aescrypt -e -p abc^^123 C:\FooFolder2\Book2.pdf aescrypt -e -p abc^^123 C:\FooFolder2\Fielding.pdf aescrypt -e -p abc^^389 C:\FooFolder2\Pitching.pdf

. . . you will be able to encrypt individual files that you specify en masse. Switching the '-e' to '-d' will let you decrypt multiple files.

An Apple Locks Tighter Than a Droid

Apple iPhones have a definite security edge over Android phones.  Because droids can only use Full Disk Encryption each time a passcode lock is entered it remains in RAM until the phone is rebooted. 

iPhones can also use file based encryption which lets them be more tightly secured as soon as they are locked.  Some data can be accessed before the phone is rebooted, and so the keys don't have to stay in RAM. 

Androids can employ ARM TrustZone which forces encryption keys to be derived from the device itself making offline dictionary attacks more difficult.