The heart of a Feistel block cipher is the function F or S-boxes.

Increasing the number of rounds of Feistel cipher improves its security.

All other things being equal, smaller block size means greater security.

DES uses a 56-bit block and a 64-bit key.

Triple DES with two keys has a key size of 168-bit.

AES uses an iterative structure rather than Feistel structure.

In AES, decryption algorithm is identical to encryption algorithm.

Cipher Feedback (CFB) is normally used for secure transmission of single values.

An error in the plaintext of cipher block chaining (CBC) will propagate indefinitely.