This is a summary of my posts regarding the HC family of block cipher modes, whose aim is to provide forward secrecy at the block level:
Block ciphers modes with forward secrecy for Cryptocat/OTR
An imaginative use case for the HC encryption modes
Comparison between forward secrecy of HC modes, SCIMP and ZRTP
Comparison between HC Modes and a Stream Cipher based on a Hash function Chain
Bitslog 