14.14.1 Introduction

Block ciphers

encrypt data in chunks of typically 8 bytes, using a secret key.

Stream ciphers

operate on the data to be encrypted one byte at a time, for exemple by xoring it with a sequence of pseudorandom bytes.

Cryptographic hash functions

transform a bytesequence of arbitrary length into a short string of a fixed length of typically 16 or 20 bytes, in such a way that it is practically impossible to find two distinct strings with the same hash value.

Public key algorithms

can support both encryption and digital signatures.

Abstract building blocks

for combining ciphers (mainly for block ciphers). These objects behave like block ciphers, but delegate encryption to one or several underlying objects, in some way. For example, block ciphers are often used in a feedback mode. The ciphers by themselves know nothing about these different "modes of operation", instead this knowledge is abstracted into separate objects. If you want IDEA in Cipher Block Chaining mode, you combine an IDEA object and a CBC object.

Randomness

is essential for many cryptographic application. The toolkit includes a few different random number generators, with varying degrees of true randomness.

Frontend objects

that handle things like padding messages, or make it more convenient to use popular combinations of ciphers, feedback modes, etc.