Encryption Algorithms

Question 1

3DES (Triple Data Encryption Standard)

Answer 1

Symmetric.
Key lengths: 56, 112, 168 bits.
Block size: 64 bits.

Question 2

RC4 (Rivest Cipher 4)

Answer 2

Symmetric.
Key lengths: 40 to 2048 bits.
Stream cipher.

Question 3

Blowfish

Answer 3

Symmetric.
Key lengths: 32 to 448 bits (mainly 128 bits).
Block size: 64 bits.

Question 4

Twofish

Answer 4

Symmetric.
Key lengths: 128, 192, or 256 bits.
Block size: 128 bits.

Question 5

CAST5

Answer 5

Symmetric.
Key lengths: 40 to 128 bits.
Block size: 64 bits.

Question 6

CAST6

Answer 6

Symmetric.
Key lengths: 128, 160, 192, 224, 256 bits.
Block size: 128 bits.

Question 7

RSA (Rivest-Shamir-Adleman)

Answer 7

Asymmetric.
Key lengths: 2048 to 4096 bits (typical).
1 round.

Question 8

DSA (Digital Signature Algorithm)

Answer 8

A digital signature is an encrypted hash of a message.
The sender’s private key encrypts the hash of the message to create the digital signature.
The recipient decrypts the hash with the sender’s public key, providing authentication, non-repudiation, and integrity.

Question 9

ECC (Elliptic Curve Cryptography)

Answer 9

Asymmetric.
Key length: 256 bits (typically).

Question 10

DH (Diffie-Hellman)

Answer 10

Asymmetric.
Provides secure key exchange.

Question 11

MD5 (Message Digest Algorithm 5)

Answer 11

Hash.
128-bit hash values (digest).
512-bit blocks.
4 rounds.

Question 12

SHA-1 (Secure Hash Algorithm 1)

Answer 12

Hash.
160-bit hash values (digest).
512-bit block sizes.