Cryptography (or cryptology ; from Greek krypts, hidden, secret; and graphein, writing, or - -logia, study, respectively) is the practice and study of techniques for secure communication in the presence of third parties (called adversaries ). More generally, it is about constructing and analyzing protocols that block adversaries; various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, and electrical engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce . Cryptography prior to the modern age was effectively synonymous with encryption, the conversion of information from a readable state to apparent nonsense. The originator of an encrypted message shared the decoding technique needed to recover the original information only with intended recipients, thereby precluding unwanted persons from doing the same. Since World WarI and the advent of the computer, the methods used to carry out cryptology have become increasingly complex and its application more widespread. https://en.wikipedia.org/wiki/Cryptography