Encryption, Post Quantum Cryptography, Optical Computing, Cryptography.
115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936 different combinations. This value is used to swap, mix and substitute information in a block in a way which is designed to be easy to reverse if you know the key but impossible if you don’t.