yeo

designed to hide messages in jpg and png images without the requirement for any plain-text files.

uses aes256 on data, using an sha256 hash of the password as the encryption key.
rotates the password by 1 character, and uses an sha256 hash of that for the random seed for the image pointer access.
security and invisibility of data is currently being peer-reviewed (since ~2014). At this point it looks like no vulnerabilities have been identified yet.
this will evolve further, but remain a console / command application.

I will be adding some additional supported file types soon (thinking mp3...).

includes (default) option to compresses message with zlib before encryption

any ideas / suggestions would speed up the process.

This software is intended to be run on a system under the user's control (so keyloggers etc. are not considered).