Which Encryption Method Does An Encrypts On Either Side? And When Is a Block Cipher A Stream Cipher?
Introduction
In the encryption process for symmetric key, we normally have one method to encrypt, and then we do the reverse to decrypt. In AES, for example, we perform 10 rounds of scrambling with the encryption key and some salt, and then do the reverse of the either side. The methods are then different, as we unwind with the decryption method. It is a bit like doing on a random walk from an original starting place and using a secret value to talk you on the walk, and when you get there, you trace your steps back with the secret key. But there’s a method where you implement the same method on both sides, and that method is defined a CFB (Cipher Feedback) mode.
Normally, too, we think of AES as a block cipher, and which makes it slower and more complex in the ciphering process than stream ciphers. But, AES can be converted into a stream cipher (that processes one bit at a time) using CFB, CTR and OFB modes. This stream cipher can then be massively scaled up with the use of parallel processing, and where a stream cipher can be at least 10 times faster than its equivalent block cipher mode.
