WGU C839 - Introduction to Cryptography| 190 QUESTIONS| WITH COMPLETE SOLUTIONS.

WGU C839 - Introduction to Cryptography | 190 QUESTIONS | WITH COMPLETE SOLUTIONS. Serpent CORRECT ANSWERS: Symmetric Block Cipher Block Size: 128 bits Key Size: 128, 192, or 256 bits Rounds: 32 Network: Substitution-Permutation Tiny Encryption Algorithm (TEA) CORRECT ANSWERS: Symmetric Block Cipher Block Size: 64 bits Key Size: 128 bits Cryptography CORRECT ANSWERS: 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. Mono-Alphabet Substitution Algorithms CORRECT ANSWERS: Include Ceasar, Atbash, Affine and ROT13 Caeser Cipher CORRECT ANSWERS: Is one of the oldest methods, was used by ancient Romans. Shift of letter. Easy to crack to common words like "A" and "The". Single Substitution Weakness CORRECT ANSWERS: Using common words (A, THE, OO, EE) in English Lang to brute force single substitution ciphers. Null Cipher CORRECT ANSWERS: Hidden message in unrelated text • The sender and recipient have prearranged to use some pattern, taking certain letters from the message. Book Cipher CORRECT ANSWERS: Parties agree on a particular book. Simplest implementation to send coordinates for words Rail Fence Cipher CORRECT ANSWERS: Widely known Transposition cipher. Plaintext written in columns and transposed in rows. Recipient reconstructs the original message Symmetric Key Cryptography uses two processes CORRECT ANSWERS: Substitution (XOR the PT with key) and transposition (swapping blocks of text) DES (Data Encryption Standard) CORRECT ANSWERS: Symmetric Block Cipher Block Size: 64 bit Key Size: 56 bit Rounds: 16 rounds Feistel cipher Initialization Vector (IV) CORRECT ANSWERS: Fixed sizes of random or pseudorandom, non repeating nonce AES (Advance Encryption Standard) CORRECT ANSWERS: Symmetric Block Cipher Block Size: 128 bits Key Size: 128, 192 256 bits Rounds: 10, 12, 14 Network: Substitution Permutation IDEA (International Data Encryption Algorithm) CORRECT ANSWERS: Symmetric Block Cipher Block Size: 64 bits Key Size: 128 bits CAST 128/256 CORRECT ANSWERS: Symmetric Block Cipher Block Size: 64 bit blocks Key Size: 40 to 128 bits Two versions: 128 and 256 Electronic Codebook (ECB) CORRECT ANSWERS: Each block is encrypted independently but identical plaintext blocks are encrypted into identical ciphertext blocks IV is used on the first block Cipher Block Chaining (CBC) CORRECT ANSWERS: Each block of plaintext is XORed with the with the previous ciphertext block before being encrypted IV is used on the first block Propagating Cipher Block Chaining (PCBC) CORRECT ANSWERS: Each block of PT is XORed with the XOR of the previous PT block AND the previous CT block before being encrypted Cipher Feedback (CFB) Mode CORRECT ANSWERS: Allows encryption of partial blocks Output Feedback (OFB) CORRECT ANSWERS: Generates keystream blocks that are XORed with the PT blocks Turns block Cipher to stream Cipher Counter (CTR) CORRECT ANSWERS: Turns block cipher into stream cipher like OFB, It generates the next keystream block by encrypting successive values of a counter Co-Prime Numbers CORRECT ANSWERS: Is a number that has no factors in common with another number FISH (FIbonacci Shrinking) CORRECT ANSWERS: Software based stream cipher Vulnerable to known plaintext attacks. Hash Salt CORRECT ANSWERS: Random bits that are used as one of the input to the hash. MD5 (Message Digest 5) CORRECT ANSWERS: 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 SHA (Secure Hash Algorithm) CORRECT ANSWERS: • 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. FORK-256 CORRECT ANSWERS: • Uses 512-bit blocks • Each block is hashed into 256 bit blocks in parallel. • Still under review and not widespread. RIPEMD-160 (RACE Integrity Primitives Evaluation Message Digest) CORRECT ANSWERS: Has 128, 256 and 320 bit versions. More secure than MD5 Tiger CORRECT ANSWERS: 192 bit hash function Collision resistant design MAC and HMAC CORRECT ANSWERS: Add a key to the has to improve integrity. Uses block cipher in CBC and salt Asymmetric Cryptography CORRECT ANSWERS: • Also called Public Key Cryptography • Uses key pairs which consist of a public key and private key • The public key is made public and the private key is kept secret.