The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Vlad Alexa:
TXTcrypt is a general purpose text encryption application for sms/email/notes etc. focused on ease of use and interoperability between mobile and desktop versions.With TXTcrypt just enter your message and a password for it , now the encrypted message can only be decoded with that password , just tell it to someone , and send them message encrypted with it , they can use TXTcrypt to decode it.TXTcrypt works with any character set being unicode compliant , the encryption used is as strong as encryption export regulations allow , not military grade but namely RC4 with keys as big as 64bit depending on the length of your password as such providing a decent amount of security.