sneakText uses a custom built alphanumeric text cipher to secure just about any text-related operations you can think of. Enter a message in the interface, followed by a codeword, select ‘sneak’ or ‘unsneak’, and hit ‘do it’. The app will then either securely encrypt the message, or decrypt it.
Source
This article is over 2 years old — the linked page may have changed, moved, or been taken over since then.