HCBK stands for "Hash Commitment Before Knowledge", and is a protocol discovered by Bill Roscoe in 2005, designed to bootstrap security in ad hoc networks. A related protocol SHCBK or "Symmetrised HCBK" was discovered by Long Nguyen and Roscoe in 2006.

The benefits of HCBK protocol

• Intruder cannot improve chance of successful attack beyond 1/(number of digest values).
• Any failed attack with a chance of success can be spotted.
• Our implementation removes any possibility of complacency by customer allowing an intruder through this phase.
• Minimum requirement for human effort
• Bootstrapping secure session key low computation cost
• Allows for low cost implementation of client's side application (demo available)