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WorksheetsQuiz Introduction to Cryptography
Total questions: 20
Worksheet time: 10mins
A hospital wants to store patient records digitally. The IT team decides to use cryptography to prevent unauthorized staff from viewing sensitive data. Which primary cryptographic goal is being prioritized?
Authentication
Confidentiality
Integrity
Availability
Non-repudiation
A start-up develops a messaging app but fails to implement encryption. During a security audit, the data in transit is found to be easily intercepted. Which fundamental weakness is exposed?
Lack of confidentiality
Lack of availability
Lack of key management
Lack of hashing
Lack of redundancy
A company uses the same symmetric key for multiple years to protect payroll data. What is the main risk of this practice?
Key distribution overhead
Brute-force complexity
Key compromise over time
Increased algorithm speed
Integrity of hash function
A bank encrypts ATM PINs using DES, but attackers later brute-force the key in hours. Which measure best addresses this vulnerability?
Use hashing instead of encryption
Switch to stronger symmetric algorithms like AES
Shorten the key length
Store PINs in plaintext
Encrypt twice with DES
A professor sends exam questions as a PDF file. Students claim some questions were altered. Which mechanism ensures the file integrity?
Symmetric key
Public key
Hash function
Digital certificate
Steganography
A software vendor distributes updates with SHA-256 hash values. During download, one user finds that the computed hash differs from the official one. What does this discrepancy suggest?
The file is corrupted or tampered
The key pair expired
The update is compressed incorrectly
The symmetric key is too short
The certificate is invalid
Alice wants to send Bob a secret message using RSA. Which key should Alice use to encrypt the message so that only Bob can read it?
Alice’s private key
Alice’s public key
Bob’s private key
Bob’s public key
Shared session key
A government agency uses public-key encryption to secure classified reports. A hacker steals a user’s private key. Which cryptographic guarantee is immediately broken?
Confidentiality
Availability
Hash uniqueness
Session freshness
Digital signature verification
A CEO signs an electronic contract with her digital signature. Later, she denies ever signing it. Which property of digital signatures disproves her claim?
Confidentiality
Availability
Integrity
Non-repudiation
Symmetric distribution
A student emails an assignment with a digital signature. The lecturer confirms the file is authentic but also detects modifications. Which process revealed this issue?
Hash mismatch
Key rotation
Symmetric encryption
Certificate revocation
Double encryption
An online payment gateway uses digital certificates issued by a Certificate Authority (CA). What is the role of the CA in this context?
Encrypts all transactions
Validates ownership of public keys
Generates session keys for clients
Acts as a symmetric key manager
Prevents brute-force attacks
An e-commerce site uses SSL/TLS certificates. When users access the site, their browsers display a certificate expired warning. Which security risk does this expose?
Replay attack
Man-in-the-middle attack
Key stretching
Hash collision
Side-channel leakage
A military system generates session keys using predictable sequences like 1, 2, 3, 4, 5… What vulnerability does this introduce?
Integrity loss
Predictability of encryption keys
Replay attacks
Non-repudiation issues
Availability risk
During an online exam, random questions are selected using a pseudorandom number generator (PRNG). A student exploits the predictable seed to guess the next questions. What caused this weakness?
Non-deterministic TRNG
Deterministic algorithm of PRNG
Weak hash collision
Faulty encryption mode
Expired certificate
A company wants truly unpredictable numbers for lottery systems. Which method is the most appropriate?
Linear Congruential Generator
SHA-1 hashing
True Random Number Generator (TRNG) using atmospheric noise
Symmetric encryption
RSA modulus computation
A research team uses a PRNG for cryptographic keys. Later, an attacker reproduces the exact sequence once the seed is known. Which concept is violated?
Independence and unpredictability
Confidentiality and availability
Certificate trust
Key rotation
Non-repudiation
An attacker modifies an encrypted financial transaction in transit. At the receiver’s end, the tampering is detected even though decryption succeeded. Which mechanism provided this protection?
Confidentiality of symmetric keys
Integrity check via hashing
Public-key infrastructure
Randomized session keys
Digital certificate expiry
Alice sends Bob an encrypted email using symmetric encryption. Later, Bob wants to prove Alice was the sender. Which mechanism is still required?
A stronger symmetric key
A digital signature
A hash function
Key rotation policy
Non-deterministic TRNG
An online exam system generates one-time session tokens for every login. Tokens are encrypted and linked with digital certificates. Which cryptographic goal is MOST directly achieved?
Confidentiality only
Availability and redundancy
Integrity and authentication
Non-repudiation only
Compression and hashing
A hacker tries to impersonate a university’s secure website. Students’ browsers warn them that the certificate is invalid. Which element protects students in this situation?
Symmetric key length
Pseudorandom sequences
Hash digest comparison
Trusted Certificate Authority
Digital envelope
