WGUC839 Introduction to Cryptography Actual Exam 100% Correct Answer
1. Serpent: Symmetric Block Cipher
Block Size: 128 bits
Key Size: 128, 192, or 256 bits
Rounds: 32
Network: Substitution-Permutation
2. Tiny Encryption Algorithm (TEA): Symmetric Block Cipher
Block Size: 64 bits
Key Size: 128 bits
3. Cryptography: Deciphering secret writings, kryptos means hidden and grafo
means write. Must not be readable by interlopers over secure/hidden communica-
tions. Readable by intended recipients only.
4. Mono-Alphabet Substitution Algorithms: Include Ceasar, Atbash, Affine and
ROT13
5. Caeser Cipher: Is one of the oldest methods, was used by ancient Romans. Shift
of letter. Easy to crack to common words like "A" and "The".
6. Single Substitution Weakness: Using common words (A, THE, OO, EE) in
English Lang to brute force single substitution ciphers.
7. Null Cipher: Hidden message in unrelated text
• The sender and recipient have prearranged to use some pattern, taking certain
letters from the message.
8. Book Cipher: Parties agree on a particular book. Simplest implementation to
send coordinates for words
9. Rail Fence Cipher: Widely known Transposition cipher. Plaintext written in
columns and transposed in rows. Recipient reconstructs the original message
10. Symmetric Key Cryptography uses two processes: Substitution (XOR the
PT with key) and transposition (swapping blocks of text)
11. DES (Data Encryption Standard): Symmetric Block Cipher
Block Size: 64 bit
Key Size: 56 bit
Rounds: 16 rounds
Feistel cipher
12. Initialization Vector (IV): Fixed sizes of random or pseudorandom, non repeat-
ing nonce
13. AES (Advance Encryption Standard): Symmetric Block Cipher
Block Size: 128 bits
Key Size: 128, 192 256 bits
Rounds: 10, 12, 14
,WGUC839 Introduction to Cryptography Actual Exam 100% Correct Answer
Network: Substitution Permutation
14. IDEA (International Data Encryption Algorithm): Symmetric Block Cipher
Block Size: 64 bits
Key Size: 128 bits
15. CAST 128/256: Symmetric Block Cipher
Block Size: 64 bit blocks
Key Size: 40 to 128 bits
Two versions: 128 and 256
16. Electronic Codebook (ECB): Each block is encrypted independently but iden-
tical plaintext blocks are encrypted into identical ciphertext blocks
IV is used on the first block
17. Cipher Block Chaining (CBC): Each block of plaintext is XORed with the with
the previous ciphertext block before being encrypted
IV is used on the first block
18. Propagating Cipher Block Chaining (PCBC): Each block of PT is XORed with
the XOR of the previous PT block AND the previous CT block before being encrypted
19. Cipher Feedback (CFB) Mode: Allows encryption of partial blocks
20. Output Feedback (OFB): Generates keystream blocks that are XORed with the
PT blocks
Turns block Cipher to stream Cipher
21. Counter (CTR): Turns block cipher into stream cipher like OFB,
It generates the next keystream block by encrypting successive values of a counter
22. Co-Prime Numbers: Is a number that has no factors in common with another
number
23. FISH (FIbonacci Shrinking): Software based stream cipher
Vulnerable to known plaintext attacks.
24. Hash Salt: Random bits that are used as one of the input to the hash.
25. MD5 (Message Digest 5): Hashing Algorithm
Hash Size: 128 Bits
Block Processing: 512 Bits
specified by RFC 1321
,WGUC839 Introduction to Cryptography Actual Exam 100% Correct Answer
The length of the message (before padding) is then appended as the last 64 bits of
the message
26. SHA (Secure Hash Algorithm): • 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.
27. FORK-256: • Uses 512-bit blocks
• Each block is hashed into 256 bit blocks in parallel.
• Still under review and not widespread.
28. RIPEMD-160 (RACE Integrity Primitives Evaluation Message Digest): Has
128, 256 and 320 bit versions. More secure than MD5
29. Tiger: 192 bit hash function
Collision resistant design
30. MAC and HMAC: Add a key to the has to improve integrity. Uses block cipher in
CBC and salt
31. Asymmetric Cryptography: • 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
• The public key is used to encrypt messages and only the recipient's private key
can decrypt them
32. Types of Random Number Generators: Table Look Up
Hardware
Software
33. Eulers Totient: Counts the positive integers up to a given integer n that are
co-prime to n
34. Birthday Theorem/Paradox: You need approximately 1.174 N to have a high
probability of a collision.
35. Fortuna: A group of PRNGs
Uses a seed file.
1. Serpent: Symmetric Block Cipher
Block Size: 128 bits
Key Size: 128, 192, or 256 bits
Rounds: 32
Network: Substitution-Permutation
2. Tiny Encryption Algorithm (TEA): Symmetric Block Cipher
Block Size: 64 bits
Key Size: 128 bits
3. Cryptography: Deciphering secret writings, kryptos means hidden and grafo
means write. Must not be readable by interlopers over secure/hidden communica-
tions. Readable by intended recipients only.
4. Mono-Alphabet Substitution Algorithms: Include Ceasar, Atbash, Affine and
ROT13
5. Caeser Cipher: Is one of the oldest methods, was used by ancient Romans. Shift
of letter. Easy to crack to common words like "A" and "The".
6. Single Substitution Weakness: Using common words (A, THE, OO, EE) in
English Lang to brute force single substitution ciphers.
7. Null Cipher: Hidden message in unrelated text
• The sender and recipient have prearranged to use some pattern, taking certain
letters from the message.
8. Book Cipher: Parties agree on a particular book. Simplest implementation to
send coordinates for words
9. Rail Fence Cipher: Widely known Transposition cipher. Plaintext written in
columns and transposed in rows. Recipient reconstructs the original message
10. Symmetric Key Cryptography uses two processes: Substitution (XOR the
PT with key) and transposition (swapping blocks of text)
11. DES (Data Encryption Standard): Symmetric Block Cipher
Block Size: 64 bit
Key Size: 56 bit
Rounds: 16 rounds
Feistel cipher
12. Initialization Vector (IV): Fixed sizes of random or pseudorandom, non repeat-
ing nonce
13. AES (Advance Encryption Standard): Symmetric Block Cipher
Block Size: 128 bits
Key Size: 128, 192 256 bits
Rounds: 10, 12, 14
,WGUC839 Introduction to Cryptography Actual Exam 100% Correct Answer
Network: Substitution Permutation
14. IDEA (International Data Encryption Algorithm): Symmetric Block Cipher
Block Size: 64 bits
Key Size: 128 bits
15. CAST 128/256: Symmetric Block Cipher
Block Size: 64 bit blocks
Key Size: 40 to 128 bits
Two versions: 128 and 256
16. Electronic Codebook (ECB): Each block is encrypted independently but iden-
tical plaintext blocks are encrypted into identical ciphertext blocks
IV is used on the first block
17. Cipher Block Chaining (CBC): Each block of plaintext is XORed with the with
the previous ciphertext block before being encrypted
IV is used on the first block
18. Propagating Cipher Block Chaining (PCBC): Each block of PT is XORed with
the XOR of the previous PT block AND the previous CT block before being encrypted
19. Cipher Feedback (CFB) Mode: Allows encryption of partial blocks
20. Output Feedback (OFB): Generates keystream blocks that are XORed with the
PT blocks
Turns block Cipher to stream Cipher
21. Counter (CTR): Turns block cipher into stream cipher like OFB,
It generates the next keystream block by encrypting successive values of a counter
22. Co-Prime Numbers: Is a number that has no factors in common with another
number
23. FISH (FIbonacci Shrinking): Software based stream cipher
Vulnerable to known plaintext attacks.
24. Hash Salt: Random bits that are used as one of the input to the hash.
25. MD5 (Message Digest 5): Hashing Algorithm
Hash Size: 128 Bits
Block Processing: 512 Bits
specified by RFC 1321
,WGUC839 Introduction to Cryptography Actual Exam 100% Correct Answer
The length of the message (before padding) is then appended as the last 64 bits of
the message
26. SHA (Secure Hash Algorithm): • 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.
27. FORK-256: • Uses 512-bit blocks
• Each block is hashed into 256 bit blocks in parallel.
• Still under review and not widespread.
28. RIPEMD-160 (RACE Integrity Primitives Evaluation Message Digest): Has
128, 256 and 320 bit versions. More secure than MD5
29. Tiger: 192 bit hash function
Collision resistant design
30. MAC and HMAC: Add a key to the has to improve integrity. Uses block cipher in
CBC and salt
31. Asymmetric Cryptography: • 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
• The public key is used to encrypt messages and only the recipient's private key
can decrypt them
32. Types of Random Number Generators: Table Look Up
Hardware
Software
33. Eulers Totient: Counts the positive integers up to a given integer n that are
co-prime to n
34. Birthday Theorem/Paradox: You need approximately 1.174 N to have a high
probability of a collision.
35. Fortuna: A group of PRNGs
Uses a seed file.
