Question

There are two types of symmetric algorithms. They are ______________ and ______________. A block cipher literally encrypts the data in blocks. 64-bit blocks are quite common, although some algorithms (like AES) use larger blocks. For example, AES uses a 128-bit block. Stream ciphers encrypt the data as a stream, one bit at a time. A) Block cipher; Stream cipher

B) Cipher text; Plain text

C) DES; AES

D) Substitution cipher; Transposition cipher

Answer 1

The two types of symmetric algorithms are block ciphers, which encrypt fixed-size blocks of data, and stream ciphers, processing data continuously one bit at a time. Answer A) Block cipher; Stream cipher is correct.

Step-by-step explanation:

The two types of symmetric algorithms are block ciphers and stream ciphers. A block cipher encrypts data in fixed-size blocks, such as the 64-bit blocks that are commonly used, while some, like the Advanced Encryption Standard (AES), use 128-bit blocks. On the other hand, a stream cipher encrypts data one bit at a time, processing an input stream continuously. Therefore, the answer is A) Block cipher; Stream cipher.

For example, the Zimmerman Telegram utilized a transposition cipher, which is a type of symmetric algorithm where the plaintext is scrambled according to a set rule. Letters are rearranged, often by breaking the text into blocks and permutating the letters within each block, sometimes guided by a keyword determining the block size and the permutation pattern.