From Silent Circle:
Silent Text is a secure text messaging system for the activist, the soldier, the business traveler, the lover, the freedom fighter, the attorney, the doctor, the CXO -- the every-person who needs to keep prying eyes off their sensitive information.
Silent Text brings the strongest encryption methods to the masses, without requiring any additional technical knowledge. The creators of modern cryptography and special ops veterans have come together to create a best-of-breed product dedicated to keeping security and privacy simple and accessible to all.
Silent Text is the product, not you - we don't give you a free tool so that we can turn around and sell you and your data. You are our customer and our pledge to you is to keep you and your data secure and private. Yet, you don't have to trust us - in fact, we've developed this best-in-class encrypted communication service with the single assumption that no communication provider can be trusted. With that assumption, we created a system which can't be compromised not even by us. You and your communication partners are the sole keepers of the secret keys, therefore we can never compromise your communications, regardless of subpoenas, extortion, bribery, corruption, negligence or mishandling...
Encrypted Messaging - strong, secure, proven encryption technology.
Open source - industry and peer reviewed encryption technology. You don't have to take our word for it.
Secure File Transfer - You have more to say than fits in a text message? Go ahead, send a voice memo, a picture or video. Want to share an Excel or Word file? Numbers or Keynote? No problem!
Secure Contact Book - You can keep your contacts securely stored in our private vault..
Burn Notice - Sensitive messages you send can be set to delete minutes after being read, or you can ensure that no outgoing message exists for more than a few weeks or months, reducing data retention headaches. This applies to any message or document type. Photos, voice memos and spreadsheets included.
Passcode Lock - keep prying eyes off your private messages
Redaction - delete a previously sent message off your friend's device? You can. You can even redact them before they've been read!
Geolocation - send your location along with your messages. Or not.