CS515

Which of the following is a primary goal of information security?. Availability. Integrity. Confidentiality. All of the above.

Which of the following methods is used to ensure the confidentiality of data?. Hashing. Encryption. Digital Signatures. Firewalls.

What is the main purpose of authentication in security services?. To verify the identity of a user. To ensure the integrity of the data. To ensure data confidentiality. To control access to the system.

Which cryptographic method uses a pair of keys for encryption and decryption?. Symmetric Encryption. Asymmetric Encryption. Hashing. Digital Signatures.

Which of the following is a primary purpose of a digital signature?. To ensure data is encrypted. To confirm data integrity. To verify the identity of the sender. To authenticate the user.

What does the principle of non-repudiation ensure?. Data confidentiality. Integrity of data. That an entity cannot deny having performed an action. Availability of the system.

Which of the following is used to ensure the integrity of a message or data?. Encryption. Hashing. Digital Signature. All of the above.

Which of the following cryptographic techniques is used to generate a fixed-size string from variable-length input data?. Encryption. Hashing. Symmetric Encryption. Asymmetric Encryption.

What does the term "data confidentiality" refer to?. Data being accessible to all users. Data being kept secret from unauthorized users. Ensuring the data is available at all times. Ensuring the integrity of data.

Which of the following is NOT an example of a security service?. Authentication. Non-repudiation. Availability. Backups.

Which type of encryption algorithm is typically faster in terms of processing speed?. Symmetric encryption. Asymmetric encryption. Hashing algorithms. Both symmetric and asymmetric encryption.

What does a transposition cipher do?. Changes letters into symbols. Rearranges the positions of letters in the plaintext. Encrypts data by shifting letters. Substitutes characters from a predefined alphabet.

What is the output of encrypting the message "HELLO" with a Caesar cipher with a shift of 1?. IFMMP. HFMMP. GDKKN. IFMNP.

What makes the Caesar cipher weak?. It uses a single key. It is very slow. It has a limited number of shifts (26 possible keys). It uses complex encryption techniques.

How many possible shifts are there in the Caesar cipher?. 26. 25. 27. 50.

What is the purpose of the key in the Caesar cipher?. To decide the order of encryption. To select the character set for substitution. To determine how many positions each letter should be shifted. To rearrange the positions of letters.

What is the block size of DES?. 32 bits. 64 bits. 128 bits. 256 bits.

What type of cipher is DES?. Stream Cipher. Symmetric Block Cipher. Asymmetric Cipher. Hash Function.

How many keys are used in DES encryption?. 1. 2. 3. 4.

What is the effective key size of DES?. 64 bits. 56 bits. 48 bits. 32 bits.

How many rounds of encryption does DES use? How many subkeys ?. 8. 10. 12. 16.

What is the purpose of S-boxes in DES?. Expansion. Substitution. Permutation. Key Generation.

What does the Initial Permutation (IP) in DES do?. Generates sub-keys. Rearranges plaintext bits. Expands block size. Encrypts the data.

What replaced DES as the encryption standard?. AES. RSA. SHA. MD5.

How are the 16 sub-keys generated in DES?. Using the plaintext. Using a key schedule algorithm. Using XOR operations. Using S-boxes.

What is the role of the Expansion Permutation in DES?. Reduces the block size. Expands the 32-bit half-block to 48 bits. Encrypts the plaintext. Generates random numbers.

How does 3DES work?. Encrypts three blocks simultaneously. Applies DES three times with different keys. Doubles the block size. Uses XOR instead of substitution.

Which mode of operation encrypts each block of plaintext independently?. CBC. CTR. ECB. GCM.

In which mode does each plaintext block depend on the previous ciphertext block?. CFB. ECB. CBC. CTR.

Which mode of operation allows parallel encryption of blocks?. CBC. CFB. CTR. ECB.

Which mode uses a counter that is incremented for each block of plaintext?. CBC. CTR. ECB. CFB.

Which mode is known for producing identical ciphertext for identical plaintext blocks?. CBC. GCM. ECB. CFB.

What type of feedback is used in CFB mode?. Output feedback. Cipher feedback. Counter feedback. Key feedback.

Which mode is known for having error propagation, where a single bit error in ciphertext affects multiple plaintext blocks?. CFB. ECB. CBC. OFB.

Which mode of operation can be used for stream ciphers?. CBC. CTR. RSA. ECB.

In which mode does the IV (Initialization Vector) play a critical role in ensuring security by being unique for each encryption?. ECB. CBC. RSA. SHA.

What is the primary disadvantage of using ECB mode?. It cannot encrypt data larger than a block size. Identical plaintext blocks produce identical ciphertext. It is very slow in parallel environments. It requires padding.

In which mode is the IV reused for each encryption block, making it susceptible to certain attacks?. SHA. GCM. ECB. CBC.

What does RSA stand for?. Random Secure Algorithm. Rivest Shamir Adleman. Reliable Security Algorithm. Robust Symmetric Algorithm.

RSA is an example of which type of encryption?. Symmetric encryption. Asymmetric encryption. Hashing. Stream cipher.

What are the key components of an RSA public key?. e and n. d and n. p and q. ϕ(n), n and e.

What is the role of the private key in RSA?. Encrypt messages. Decrypt messages. Generate prime numbers. Validate public keys.

What is the modulus n in RSA?. A large prime number. The product of two large prime numbers. The difference between two primes. The square of a prime number.

Which protocol often uses RSA for key exchange?. HTTP. FTP. SSL/TLS. DNS.

Why is RSA not suitable for encrypting large data?. It uses symmetric keys. It is computationally intensive. It cannot generate prime numbers. It does not use a modulus.

What is the output of RSA decryption?. Encrypted ciphertext. Original plaintext. Public key. Private key.

Which property of a hash function ensures that it is difficult to reverse the process and find the input?. Collision resistance. Preimage resistance. Determinism. Compression.

What is the primary output of a hash function?. Encrypted data. Fixed-size digest. Variable-sized output. Plaintext.

What does the term "collision resistance" mean?. Hashes are reversible. Different inputs always produce different hashes. It is computationally infeasible to find two inputs with the same hash. Hashes are random.

Which of the following is a cryptographic hash function?. DES. SHA-256. RSA. AES.

What is the purpose of a salt in hashing?. To compress the hash. To make the hash shorter. To prevent precomputed attacks. To increase collision resistance.

Which algorithm belongs to the SHA-2 family?. MD5. SHA-512. Blowfish. SHA-1.

Which of the following hash functions is considered broken?. SHA-1. SHA-256. SHA-3. SHA-512.

What is the typical size of an MD5 hash output?. 64 bits. 128 bits. 256 bits. 512 bits.

Why are hash functions used in digital signatures?. To encrypt data. To provide message authenticity. To compress the message for signing. To authenticate the sender.

What does a MAC ensure?. Confidentiality. Authenticity and integrity. Encryption and decryption. Key exchange.

Which of the following is a type of MAC?. HMAC. RC4. DES. Blowfish.

What is the primary input to a MAC?. Plaintext and a public key. Message and a secret key. Ciphertext and a private key. Message and a nonce.

HMAC is based on which cryptographic primitive?. Block cipher. Stream cipher. Hash function. Public key cryptography.

What does "keyed" in a MAC mean?. The MAC depends on the hash algorithm. The MAC computation uses a secret key. The MAC output is always unique. The MAC uses symmetric encryption.

Which is more secure: a hash function or a MAC?. Hash function. MAC. Both are equally secure. Neither is secure.

What is the primary purpose of a digital signature?. Encrypting data. Validating data integrity and authenticity. Enhancing file compression. Ensuring anonymity.

Which cryptographic technique is used in digital signatures?. Symmetric encryption. Asymmetric encryption. Block cipher. Steganography.

What component is essential for creating a digital signature?. Public key. Private key. Hash value. Both b and c.

Which algorithm is not commonly used for digital signatures?. RSA. DSA. AES.

What does the recipient need to verify a digital signature?. The private key of the signer. The public key of the signer. The hash algorithm. The CA’s private key.

What happens if a digital document is modified after it has been signed?. The signature becomes invalid. The hash value remains unchanged. The signature still works. The document is re-signed automatically.

What is the role of a Certificate Authority (CA)?. To generate private keys. To verify and issue public key certificates. To create digital signatures. To encrypt documents.

What is the output of a hashing algorithm in a digital signature?. Encrypted text. Plaintext. Digital certificate. Message digest.

How does a digital signature ensure non-repudiation?. By using a password. By encrypting data with the sender’s public key. By proving the signature came from the private key holder. By embedding a timestamp.

What does a valid digital signature guarantee?. The sender’s anonymity. The authenticity and integrity of the document. That the message is encrypted. The prevention of document sharing.