Telegram unofficial — fast and safe internet messenger
Telegram is a messenger app with a focus on speed and security. It’s superfast, simple and secure. Now with iPad and iOS 7 support
1) Messages are signed on your device and can be decrypted only by recipient of the message
2) Allows "Group chats"
3) "Private chat" feature allows you to have hidden chats with some of your friends
Based on Telegram for iPhone messenger