WGU C839 - Introduction to Cryptography Actual Exam With 100% Correct Verified Answer 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) 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 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 Block Chaining (PCBC) Allows encryption of partial blocks ---------- Correct Answer -------- Cipher Feedback (CFB) Mode Generates keystream blocks that are XORed with the PT blocks Turns block Cipher to stream Cipher ---------- Correct Answer -------- Output Feedback (OFB) Turns block cipher into stream ciphe r like OFB, It generates the next keystream block by encrypting successive values of a counter -----
----- Correct Answer -------- Counter (CTR) Is a number that has no factors in common with another number ---------- Correct Answer -------- Co-Prime Num bers Software based stream cipher Vulnerable to known plaintext attacks. ---------- Correct Answer -------- FISH (FIbonacci Shrinking) Random bits that are used as one of the input to the hash. ---------- Correct Answer ------
-- Hash Salt Hashing Algorithm Hash Size: 128 Bits Block Processing: 512 Bits specified by RFC 1321 The length of the message (before padding) is then appended as the last 64 bits of the message ---------- Correct Answer -------- MD5 (Message Digest 5) • SHA -1 160 bit hash function similar to MD5. Designed by NSA • SHA -2 Consists of SHA 224, 256, 384, and 512. They differ in word sizes but 512 bit blocks • SHA -3 still in development. Should be complete by NIST by 2012. ---------- Correct Answer -------- SHA (Secure Hash Algorithm) • Uses 512 -bit blocks • Each block is hashed into 256 bit blocks in p arallel. • Still under review and not widespread. ---------- Correct Answer -------- FORK -256 Has 128, 256 and 320 bit versions. More secure than MD5 ---------- Correct Answer ------
-- RIPEMD -160 (RACE Integrity Primitives Evaluation Message Digest) 192 bit hash function Collision resistant design ---------- Correct Answer -------- Tiger Add a key to the has to improve integrity. Uses block cipher in CBC and salt ---------- Correct Answer -------- MAC and HMAC • Also called Public Key Cryptography • Uses key pairs which consist of a public key and private key • The public key is made pu blic and the private key is kept secret • The public key is used to encrypt messages and only the recipient's private key can decrypt them ---------- Correct Answer -------- Asymmetric Cryptography Table Look Up Hardware Software ---------- Correct Answe r -------- Types of Random Number Generators Counts the positive integers up to a given integer n that are co -prime to n ---------- Correct Answer -------- Eulers Totient 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 hidde n 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 -------- Mono -
Alphabet 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". ---------- Corre ct Answer -------- Caeser Cipher
------- 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) 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 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 Block Chaining (PCBC) Allows encryption of partial blocks ---------- Correct Answer -------- Cipher Feedback (CFB) Mode Generates keystream blocks that are XORed with the PT blocks Turns block Cipher to stream Cipher ---------- Correct Answer -------- Output Feedback (OFB) Turns block cipher into stream ciphe r like OFB, It generates the next keystream block by encrypting successive values of a counter -----
----- Correct Answer -------- Counter (CTR) Is a number that has no factors in common with another number ---------- Correct Answer -------- Co-Prime Num bers Software based stream cipher Vulnerable to known plaintext attacks. ---------- Correct Answer -------- FISH (FIbonacci Shrinking) Random bits that are used as one of the input to the hash. ---------- Correct Answer ------
-- Hash Salt Hashing Algorithm Hash Size: 128 Bits Block Processing: 512 Bits specified by RFC 1321 The length of the message (before padding) is then appended as the last 64 bits of the message ---------- Correct Answer -------- MD5 (Message Digest 5) • SHA -1 160 bit hash function similar to MD5. Designed by NSA • SHA -2 Consists of SHA 224, 256, 384, and 512. They differ in word sizes but 512 bit blocks • SHA -3 still in development. Should be complete by NIST by 2012. ---------- Correct Answer -------- SHA (Secure Hash Algorithm) • Uses 512 -bit blocks • Each block is hashed into 256 bit blocks in p arallel. • Still under review and not widespread. ---------- Correct Answer -------- FORK -256 Has 128, 256 and 320 bit versions. More secure than MD5 ---------- Correct Answer ------
-- RIPEMD -160 (RACE Integrity Primitives Evaluation Message Digest) 192 bit hash function Collision resistant design ---------- Correct Answer -------- Tiger Add a key to the has to improve integrity. Uses block cipher in CBC and salt ---------- Correct Answer -------- MAC and HMAC • Also called Public Key Cryptography • Uses key pairs which consist of a public key and private key • The public key is made pu blic and the private key is kept secret • The public key is used to encrypt messages and only the recipient's private key can decrypt them ---------- Correct Answer -------- Asymmetric Cryptography Table Look Up Hardware Software ---------- Correct Answe r -------- Types of Random Number Generators Counts the positive integers up to a given integer n that are co -prime to n ---------- Correct Answer -------- Eulers Totient 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 hidde n 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 -------- Mono -
Alphabet 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". ---------- Corre ct Answer -------- Caeser Cipher
