In an asymmetric cryptographic process one key is used to encipher the data, and a different but corresponding key is used to decipher the data. A system that uses this type of process is known as a public key system. The key that is used to encipher the data is widely known, but the corresponding key for deciphering the data is a secret. For example, many people can use your public key to send enciphered data to you with confidence, knowing that only you should possess the secret key for deciphering the data.
Public key cryptographic algorithms are used in processes that simplify the distribution of secret keys, assuring data integrity and provide nonrepudiation through the use of digital signatures.
The widely known and tested public key algorithms use a relatively large key. The resulting computer processing time makes them less than ideal for data encryption that requires a high transaction rate. Public key systems, therefore, are often restricted to situations in which the characteristics of the public key algorithms have special value, such as digital signatures or key distribution. PKA calculation rates are fast enough to enable the common use of digital signatures.