Cryptography is the science dealing with keeping messages secure. Cryptography is normally used to develop methods to keep messages and information secure by encrypting it. Encryption is a method of converting the data or information from a normal readable format, known as plaintext, into a format that is not readable, known as ciphertext, without being converted back to plaintext. Historically encryption techniques developed with the science of cryptography were used to keep important communications secret.

Today cryptography is used to:

  1. Keep messages secret.
  2. Provide digital signatures so receivers of messages can be sure of who sent them.
  3. Provide authentication