Cipher

Ciphers came about when people realised they needed to confidentially share information with one another without third parties potentially violating their privacy. They have been prevalent for decades, with the first ones relying on pen and paper instead of a computer programme.

An algorithm used to encrypt or decrypt information, ciphers are a critical concept in cryptography because they are part of the science of secure communication. They typically start with the plaintext of what the individual wants to send out, and then the cipher transforms this plaintext into ciphertext, sending it to the receiver, who has additional information (known as a ‘key’) to decipher the message.