WGU C839 - Introduction to Cryptography
Real Exam With Complete Solutions
Symmetric Block Cipher
Block Size: 64 bits
Key Size: 128 bits ----------
... [Show More] Correct Answer -------- IDEA (International Data Encryption
Algorithm)
Symmetric Block Cipher
Block Size: 64 bit blocks
Key Size: 40 to 128 bits
Two versions: 128 and 256 ---------- Correct Answer -------- CAST 128/256
Symmetric Block Cipher
Block Size: 128 bits
Key Size: 128, 192, or 256 bits
Rounds: 32
Network: Substitution-Permutation ---------- Correct Answer -------- Serpent
Symmetric Block Cipher
Block Size: 64 bits
Key Size: 128 bits ---------- Correct Answer -------- Tiny Encryption Algorithm (TEA)
Deciphering secret writings, kryptos means hidden and grafo means write. Must not be
readable by interlopers over secure/hidden communications. Readable by intended
recipients only. ---------- Correct Answer -------- Cryptography
Include Ceasar, Atbash, Affine and ROT13 ---------- Correct Answer -------- MonoAlphabet Substitution Algorithms
Is one of the oldest methods, was used by ancient Romans. Shift of letter. Easy to crack
to common words like "A" and "The". ---------- Correct Answer -------- Caeser Cipher
Using common words (A, THE, OO, EE) in English Lang to brute force single
substitution ciphers. ---------- Correct Answer -------- Single Substitution Weakness
Hidden message in unrelated text
• The sender and recipient have prearranged to use some pattern, taking certain letters
from the message. ---------- Correct Answer -------- Null Cipher
Parties agree on a particular book. Simplest implementation to send coordinates for
words ---------- Correct Answer -------- Book Cipher
Widely known Transposition cipher. Plaintext written in columns and transposed in
rows. Recipient reconstructs the original message ---------- Correct Answer -------- Rail
Fence Cipher
Substitution (XOR the PT with key) and transposition (swapping blocks of text) ----------
Correct Answer -------- Symmetric Key Cryptography uses two processes
Symmetric Block Cipher
Block Size: 64 bit
Key Size: 56 bit
Rounds: 16 rounds
Feistel cipher ---------- Correct Answer -------- DES (Data Encryption Standard)
Fixed sizes of random or pseudorandom, non repeating nonce ---------- Correct Answer -
------- Initialization Vector (IV)
Symmetric Block Cipher
Block Size: 128 bits
Key Size: 128, 192 256 bits
Rounds: 10, 12, 14
Network: Substitution Permutation ---------- Correct Answer -------- AES (Advance
Encryption Standard)
Each block is encrypted independently but identical plaintext blocks are encrypted into
identical ciphertext blocks
IV is used on the first block ---------- Correct Answer -------- Electronic Codebook (ECB)
Each block of plaintext is XORed with the with the previous ciphertext block before
being encrypted
IV is used on the first block ---------- Correct Answer -------- Cipher Block Chaining (CBC)
Each block of PT is XORed with the XOR of the previous PT block AND the previous
CT block before being encrypted ---------- Correct Answer -------- Propagating Cipher [Show Less]