Explanation:
Computer processing time is increased for longer asymmetric encryption keys, and the increase may be disproportionate. For example, one benchmark showed that doubling the length of an RSA key from 512 bits to 1,024 bits caused the decrypt time to increase nearly six-fold. An asymmetric algorithm requires more processing time than symmetric algorithms. A hash is shorter than the original message; therefore, a smaller overhead is required if the hash is encrypted rather than the message. Use of a secret key, as a symmetric encryption key, is generally small and used for the purpose of encrypting user data.