Mode of operations (on block cipher)¶

How to encrypt arbitrary length of message with a block cipher?

Padding¶

1. Add a single "1"
2. then add "0"s to complete the final block

ECB(Electronic CookBook) mode¶

Independently.

TOTALLY INSECURE: like a great substitution cipher

CBC(Cipher Block Chaining) mode¶

Generally secure.

CFB(Cipher Feedback) Mode¶

OFB(Output Feedback) Mode¶

CTR(counter) Mode¶