Cryptography means the science of writing or solving codes.
The concept has taken on new value in the digital age, in which cryptographers use the techniques to secure computer systems and digital communications.
This includes both stored data and data travelling across communication channels.
As well as obscuring the content of messages from unintended audiences, cryptography aims to ensure that the information is not altered and that the identities of both parties can be confirmed to the other.
Since no communication channel is perfect, using cryptographic techniques can be necessary to protect information from adversaries.
While it is a key part of advanced cyber security practices, cryptography is used regularly in day-to-day life, such as when paying with credit cards.
Though the terms are related, cryptography differs from encryption. Cryptography more refers to the science of secret codes whereas encryption is an actual cryptographic process. Encryption essentially means scrambling data using an algorithm so that only somebody with a secret key can access it.
It also differs from cryptology, which refers specifically to the study of codes.
The world is derived from Greek words meaning ‘secret’ and ‘writing.
WhatsApp, the popular chat app, has introduced end-to-end encryption for the messages of all of its users.
Cryptography is not a new concept in the computer age, however. For example, Julius Caesar gave his name to one of the earliest known ciphers, the Caesar cipher. This shifts every letter in the alphabet a certain number of places in the alphabet. For example, B stands in for A, C stands in for B, etcetera.
Cryptography is often a core module in cyber security courses. It requires a knowledge of programming as well as some understanding of probability and theory of computation and algorithm analysis.
Key topics include encryption, pseudo-random generation, digital signatures, two-party protocols and zero-knowledge.