Chunks Review

Messages in a block cipher are broken up into blocks, and each block is encrypted separately.

For example, let's say we are using a cipher that requires 256-bit blocks. We have a message of 650 bits that we want to encrypt. The algorithm would break that message up into three blocks:

block1 = first 256 bits
block2 = next 256 bits
block3 = last 138 bits

The last block is then padded with extra garbage bits so that it also has 256 bits of data. That padding is stripped off when the message is decrypted.