WGU C839 - Introduction to Cryptography Real Exam With Complete Solutions

WGU C839 - Introduction to Cryptography Real Exam With Complete Solutions Symmetric Block Cipher Block Size: 64 bits Key Size: 128 bits ---------- 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