Various potential attack experiments are implemented to check the validity of the proposed cryptographic system.

You said earlier that the NSA endorsed a cryptographic system that they themselves could crack.

These are ways of exploiting physical indicators from a cryptographic system to get around its protections.

An Irish mathematician has solved a code-cracking challenge designed to test the security of alternative cryptographic systems.

But hidden drawers, lockable diaries and cryptographic systems could not conceal from Briony the simple truth: she had no secrets.