CPK is the abbreviation of "combined public key", which is called combined public key in Chinese. It is an encryption algorithm that generates a large-scale key with a small amount of resources. Combined public key CPK( Combined Public Key) digital signature protocol and ID-based key exchange protocol satisfy the scale of proof and the directness of verification, truly realize Shamir's idea, and open up a new way to solve the scale by combination.

PPK is an index used to calculate process performance or process performance in SPC control chart.

CPK principle:

CPK key management system is a key generation and management system based on discrete logarithm problem, which constructs public key and private key matrix according to the mathematical principle of discrete logarithm problem.

Hash function and cryptographic transformation are used to map the entity's identity to the row coordinate and column coordinate sequence of the matrix, which is used to select and combine matrix elements and generate a large number of public key and private key pairs composed of public key and private key, thus realizing identity-based super-large-scale key production and distribution.