Electronic Code Book (ECB) and Cipher Block Chaining (CBC)

Encryption normally works by taking a number of text blocks, and then applies a key to these to produce cipher blocks. Typical block sizes are 128 or 256 bits. Unfortunately, the cipher blocks could end up being the same, for the same input text. Thus an intruder could try and guess the cipher text. This is known as electronic code book. For example if we use 3DES to encrypt the word…