End-to-end Encryption in Transit:
StealthChat uses end-to-end encryption technology to encrypt your messages, files and calls in transit. This provides an additional layer of protection over industry standard SSL/TLS. The end-to-end encryption means that only you and the receiver can read them. Each session is encrypted with a unique key pair and in the extreme event that your connection is monitored the data still cannot be decrypted. The message encryption is based on the "Off-the-record" (OTR) messaging protocol:https://en.wikipedia.org/wiki/Off-the-Record_Messaging
The Voice Over IP (VoIP) encryption is based on the Secure Real Time Transport (SRTP) protocol:https://en.wikipedia.org/wiki/Secure_Real-time_Transport_Protocol
StealthChat automates the end-to-end key exchange when the communication session is initiated and the keys are used to encrypt calls, chats and files. Unlike some other "secure" apps, StealthChat encrypts all communication to ensure that unencrypted information cannot be exchanged inadvertently.
Encrypted display :
StealthChat provides a unique and optional screen encryption. Information on the StealthChat screen can be set to switch to encrypted mode. The screen is encrypted after a timeout period or after the app is sent to the background. The encrypted screen mode can be unlocked with a password, with a picture lock or with TouchID. This feature protects against "shoulder surfing" where somebody looks over your shoulder or picks up your phone when the device is unlocked. The Encrypted Display prevents unauthorized users from viewing your message history or who you have been talking with.
Encrypted on disk:
StealthChat stores your message history securely on disk using industry best practices including AES/EAX encryption using a PBKDF derived password. In addition, you can set a burn timer for your messages, after which they are deleted from disk on your device and your friend’s device.