Kryptos (ad-supported)

256-bit AES text encryption and password generation

Kryptos offers 256-bit AES text encryption, as well as salted CBC encryption with arbitrary key length. It also features password generation in many different character sets (Unicode, ASCII, letters & numbers, only letters, only numbers, or the unique base-256 number system Kryptos uses in its encryption feature).

Base-256 allows any byte to be represented as a single character, whereas the popular base-64 encoding requires 2 characters per byte. This means that encrypted messages are much shorter.

DISCLAIMER:

This is the ad-supported version of Kryptos, which is why it requires internet access as a permission. The ad-free version does not require any internet access. That being said, if you're working with sensitive data it's always a good idea to disconnect your device from all network access.