System and method for efficient and semantically secure symmetric encryption over channels with limited bandwidth

摘要

One embodiment of the present invention provides a system for enhancing security in a secure communication channel. During operation, the system collects contextual information associated with a mobile device or a user of the mobile device and determines whether a trigger condition is met based on the collected contextual information. In response to determining that the trigger condition is met, the system performs a first type of key-ratcheting operation on a current cryptographic key to update the cryptographic key. In response to determining that the trigger condition is not met, the system performs a second type of key-ratcheting operation on the current cryptographic key to update the cryptographic key. The system then encrypts a to-be-sent message using an encryption key associated with the updated cryptographic key.