Original: In cryptography , ciphertext is the result of the process ( known as encryption ) of transforming information ( referred to as plaintext ) using an algorithm ( called cipher ) to make it unreadable Hansche , Berti & Hare , Official ( ISC ) Guide to the CISSP Exam , Auerbach Publications , p. 379 , ISBN 0-8493-1707-X to anyone except those possessing special knowledge , usually referred to as a key .
Simplified: In cryptography , ciphertext refers to the output of the encryption process , the process of transforming information ( referred to as plaintext ) using an algorithm ( called cipher ) to make it unreadable to anyone except those who own special information about it , usually referred to as a key .