Stream and Block Ciphers 6.1

Question 1

Stream Cipher

Answer 1

Used for real time information streaming. Encryption is done one bit or byte at a time. It’s high speed because of the low hardware complexity. Used with symmetric encryption. Not used in asymmetric. The starting state should never be the same twice. The key is often combined with an initialization vector (IV)

Question 2

Block Cipher

Answer 2

Encrypt fixed-length group. Often 64 or 128 bits. If the block is smaller than that, there will be a padding of information to make it fit. Each block is encrypted or decrypted independently. They commonly use symmetric encryption.