With all of the privacy invasion news (read: PRISM) going around nowadays, lots of encryption and security solutions have been seeing record sales. iMessage uses end-to-end encryption, but the security of Skype, AIM and MSN are questionable.

The popular IM+ app (free version, pro version) is offering their $4.99 “off-the-record” feature for just 99 cents until the end of tomorrow. Rather than using a single, proprietary messaging services, IM+ uses the OTR standard that can be used with many messaging services and across many devices.

On their Facebook page, the company details OTR.

In short, it’s an encryption system that works with any service by creating encryption/decryption keys that only last for a short amount of time. As detailed on the Facebook post, Pidgin (for Windows) and Adium (for Mac) support OTR.

This distinguishes OTR from other encryption methods. For example, almost every messenger (including IM+) uses SSL encryption to connect to its own server. But what happens then, when it connects to AOL, Facebook, ICQ or any other IM server? There is no guarantee that messages are encrypted there and on the way to your contact.

But if you use OTR, no matter how many servers are used to pass message from you to your contact – none of them is able to decrypt the message, it may be decrypted only on your contact’s smartphone or computer.

If you want to keep all of your communications secure from all outsiders, definitely check out  IM+ in the App Store (free version, pro version).