This image demonstrates three types of crytographic algorithm using diagrams and text. The first two diagrams show the word 'plaintext' with an arrow leading to the word 'ciphertext', and then another arrow leading to another 'plaintext'. In the first diagram, there are identical keys drawn above both arrows. The text beneath reads 'Secret key (symmetric) cryptography. SKC uses a single key for both encryption and decryption.' The second diagram is identical, but the keys are drawn in different colours. The text beneath reads 'Public key (asymmetric) cryptography. PKC uses two keys, one for encryption and the other one for decryption.' The third diagram shows the word 'plaintext' with an arrowing leading to the word 'ciphertext'. The text beneath reads 'Hash function (one-way cryptography). Hash functions have no key since the plaintext is not recoverable from the ciphertext.'