Cryptography Interview Questions
Cryptography is an indispensable field that safeguards sensitive data against unauthorised access. Cryptographic protocols use mathematical algorithms and protocols that ensure data confidentiality, integrity, authenticity, and nonrepudiation.
Interview questions on cryptography, you may be asked various questions designed to assess your understanding of cryptographic concepts, algorithms and protocols ranging from fundamental topics like symmetric and asymmetric encryption to more advanced topics such as hash functions, digital signatures and public key cryptography.
We aim to equip you with sample interview questions on cryptography and explanations, in-depth resources and references so you can expand your understanding.
We aim to assist in your preparation forcryptography exam questions and answers as a beginner or experienced professional alike,as well as viva questions for cryptography and network security,giving them confidence for success!
This blog offers valuable insights that will prepare them for their upcoming interviews in cryptography.
Let’s get started.
1. What is cryptocurrency?
Cryptocurrency is a digital or virtual currency that uses cryptography for security, allowing for secure and decentralized transactions without a central authority.
2. What is the purpose of cryptography?
Cryptography aims to ensure the security and confidentiality of information by encrypting or decrypting it to prevent unauthorised access.
3. What are some applications of cryptography?
Cryptography has applications in various fields, including Internet security, banking, and cybersecurity.
It allows secure data storage and transmission between parties and is crucial for protecting sensitive information.
4. What is the difference between symmetric and asymmetric key cryptography?
Symmetric key cryptography involves using the same key for encryption and decryption, while asymmetric key cryptography involves using two different keys, one for encryption and one for decryption.
5. Why is end-to-end encryption essential for protecting sensitive information?
End-to-end encryption ensures that the sender and receiver of a message are the only ones who can read and decrypt it, protecting sensitive information from interception by unauthorised parties.
6. What is blockchain technology?
Blockchain technology is a distributed ledger system that uses cryptography and hashing functions to secure data and ensure the integrity and immutability of transactions.
7. What is the Caesar cipher?
The Caesar cipher is a simple substitution cipher that shifts each letter in the plaintext by a certain number of positions down the alphabet to create the ciphertext.
8. What is a cipher?
A cipher is an algorithm used in cryptography to encrypt or decrypt data. It scrambles the data sounauthorised parties cannot read it without the decryption key.
9. What is symmetric encryption?
Symmetric encryption protects data on servers and data centres by using a single key for encryption and decryption.
This ensures messages are encrypted and decrypted correctly, preventing snooping on malicious actors.
10. What is the key exchange?
Key exchange is the process of securely exchanging encryption keys between two parties. This is done beforehand using algorithms like the Diffie-Hellman key exchange protocol to ensure that messages are encrypted and decrypted correctly.
11. What is private key cryptography?
Private key cryptography uses a single key for encryption and decryption, with both sender and receiver having a pre-shared secret key.
The secret key should not be sent along with the cipher text to avoid defeating the purpose of cryptography.
12. What are the two categories of ciphers used in public key cryptography?
The two categories of ciphers used in public key cryptography are stream ciphers and RC4, CELSA, and Panama.
Stream ciphers encrypt basic information one bit at a time, while RC4, CELSA, and Panama encrypt binary data.
13. What is a single-key structure in symmetric key cryptography?
A single-key structure in symmetric key cryptography is a simple structure that allows for easy transmission of a secret key to both sender and receiver.
This simplifies communication and maintenance, making it ideal for everyday communications.
14. What is the risk associated with using symmetric key cryptography?
A risk associated with symmetric key cryptography is key sharing, as both the sender and receiver must have a pre-shared secret key.
This cannot be easy to manage in large organizations or with many users.
15. What is asymmetric key encryption?
Asymmetric key encryption uses a double layer of protection, with a private and public key.
The public key encrypts information pre-transit, while the private key decrypts data post-transit. Both keys must belong to the receiver of the message.
16. What is a journalist’s practical scenario when using symmetric key cryptography?
A journalist’s practical scenario when using symmetric key cryptography would be sending encrypted data to Ryan, ensuring that the information cannot be decoded even if intercepted.
17. Who should belong to the keys in asymmetric key encryption?
The sender and receiver should belong to the keys in asymmetric key encryption. The keys must be kept private at all times to prevent unauthorized access.
18. What is the purpose of the private and public keys in asymmetric key encryption?
The private key in asymmetric encryption is used for decryption, while the public key is used for encryption.
19. What are the risks associated with symmetric key cryptography?
The risks associated with symmetric key cryptography include key sharing and the possibility of a single point of failure.
20. How does symmetric critical cryptography work?
Symmetric key cryptography relies on a single key for encryption and decryption, with both sender and receiver having a pre-shared secret key.
The private key should not be sent along with the cipher text to avoid defeating the purpose of cryptography.
21. What is symmetric encryption used for?
Symmetric encryption protects data on servers and data centres, ensuring minimal to no delay when recalled.
It plays a significant role in verifying website server authenticity, exchanging necessary encryption keys, and generating sessions for maximum security.
22. What does asymmetric key encryption provide the double layer of protection?
The double layer of protection provided by asymmetric key encryption includes pre-transit encryption using the public key and post-transit decryption using the private key.
23. How can asymmetric key encryption be used in a practical scenario?
Asymmetric key encryption can be used in a practical scenario to ensure the security of everyday communications, such as a journalist sending encrypted data to Ryan.
24. What is asymmetric cryptography?
Asymmetric cryptography is a secure method of transmitting ciphers text without a public key, allowing the receiver to decrypt it using their private key.
25. How does asymmetric cryptography solve the flaw in symmetric key cryptography?
Asymmetric cryptography solves the flaw in symmetric key cryptography by making it impossible to substitute other keys for decryption, allowing for frequent exchange of personal data using the same set of keys.
26. What is the purpose of hashing in asymmetric key cryptography?
Hashing, scrambling information beyond recognition, is another crucial advantage of asymmetric key cryptography. Hash functions generate a hash value or digest meant to be irreversible and cannot be converted back to their original value.
They are used for password storage, identity verification, and integrity checks.
Cryptography Training
Asymmetric key cryptography offers advantages over traditional symmetric encryption methods, such as eliminating the need for a reliable key-sharing channel and ensuring confidentiality. It also has more extensive key lengths, making it harder to break into via brute force.
28. How does asymmetric key cryptography ensure confidentiality?
Asymmetric key cryptography ensures confidentiality by using a public key for encryption and a private key for decryption, meaning only the intended recipient can read the message.
29. What is the tamper-proof characteristic of asymmetric key cryptography?
Asymmetric key cryptography has a tamper protection feature that prevents messages from being intercepted and changed without invalidating the private key used to encrypt the data.
30. What is hashing in asymmetric key cryptography?
Hashing is a crucial advantage of asymmetric key cryptography. It is the process of scrambling information beyond recognition, generating a hash value or digest.
These hashes are meant to be irreversible and cannot be converted back to their original value.
31. How is hashing used for password storage and identity verification?
Websites use hashing to store user passwords, which are then passed through the hash function when a user creates a new account.
If the hash value matches the one stored on the central server, the password is correct, preventing data breaches or hacks.
32. What is the use of asymmetric key cryptography in blockchain architecture?
Asymmetric key cryptography is used in blockchain architecture to authorize transactions and maintain the system.
If both ends approve, its two critical structures ensure changes are reflected across the network.
33. How does asymmetric key cryptography eliminate the need for a reliable key-sharing channel?
Asymmetric key cryptography eliminates the need for a reliable key-sharing channel because the public key can encrypt the message, and the private key can decrypt it.
34. How is asymmetric key cryptography used to monitor encrypted browsing sessions?
Asymmetric key cryptography is used to monitor encrypted browsing sessions by verifying websites of authenticity and exchanging encryption keys for maximum security.
35. What is a hash function?
A hash function is a set of mathematical calculations performed on two blocks of data, with the primary input divided into two blocks of similar size.
36. What is the block size in a hash function?
The block size depends on the algorithm used.
37. What are hash collisions?
Hash collisions are common issues where two users have the same password, but techniques like solving can help reduce them.
38. What is the solved value?
The solved value is a unique random keyword added to the input in the solving technique to reduce hash collisions.
39. What is pepping?
Pepping is a technique that adds a random string of data, called the paper, to input before passing it to the hash function to prevent hackers from cracking into all passwords.
40. What is the difference between DES and Crystal ciphers?
DES is a symmetric block cipher that implements substitution and permutation alternately. In contrast, Crystal ciphers are based on the Shannon structure and implement substitution and permutation alternately to combat brute force attacks.
Crystal ciphers are a backbone in the development of many symmetric block ciphers.
41. What is a public-wide competition?
A public-wide competition is a process where many people are invited to participate in a challenge or event, often to develop new technology or solutions to a problem.
In the context of encryption, public-wide competition can lead to the development of new and advanced encryption standards, such as the Vindale algorithm.
42. What is a crystal cipher?
A crystal cipher is a symmetric block cipher that implements substitution and permutation alternately, reducing redundancy and increasing complexity to combat brute force attacks.
The process involves dividing the encrypted block into two parts, using different encryption keys for each run, and reversing the decryption process to obtain the final cipher text.
This structure was a backbone in the development of many symmetric block ciphers.
43. When was the advanced encryption standard developed?
The advanced encryption standard was created in 2002. It replaced the previous encryption standard, D E S, which was deemed too slow for communication channels.
44. What is the Crystal cipher structure?
The Crystal cipher structure is a method of encryption that involves dividing plain text into two halves, passing each half through a function using a unique encryption key, and then using an XOR input with the left half of the initial plain text to decrypt the information.
45. What is the FISER cipher?
The FISER cipher is a block cipher used in the Crystal cipher structure. It is considered safest when the block size is large, but larger block sizes can slow down encryption and decryption speeds.
46. Compare symmetric and asymmetric encryption?
Symmetric encryption involves using the same key for encryption and decryption, while asymmetric encryption involves using two different keys, one for encryption and one for decryption.
47. What is the purpose of DES encryption?
DES encryption is a software application that converts 64-bit plain text into 64-bit cipher text using the Fistel cipher structure.
It is implemented in the DES algorithm and provides the cipher text.
48. What are the modes of operation for DES encryption?
DES encryption has five modes of operation for better execution speed: electronic codebooks, cipher block chaining, cipher feedback block, output feedback method, and counter method.
49. What is the dominance of DES encryption?
The dominance of DES encryption began in 2002 when the advanced encryption standard replaced it as the accepted standard.
The NIST officially withdrew the global acceptance standard in May 2005, but triple DES has been approved for sensitive government information through 2013.
50. What led to the change in the DES algorithm?
The DES algorithm was changed due to short key lengths and increased processing power of new computers.
As encryption power increases with crucial size, DES is no longer a challenge for packing computers.
51. What are some widely used encryption methods?
Some widely used encryption methods include electronic codebooks, cipher block chaining, cipher feedback block, output feedback method, and counter method.
52. What are the benefits of using a larger block size in a block cipher?
A larger block size in a block cipher provides better security but can also slow down encryption and decryption speeds.
Cryptography Online Training
The AES encryption algorithm is a symmetric block cipher that converts 64-bit plain text into 64-bit cipher text. It is considered a secure encryption algorithm and has been widely adopted as the standard for encryption.
It is also known as the Rijndael algorithm and runs through 10 to 256 rounds.
54. What is the NIST encryption standard?
The NIST encryption standard is a set of guidelines and specifications for encryption algorithms.
It was officially withdrawn in May 2005, but the Advanced Encryption Standard (AES) has replaced it as the accepted standard.
55. What is AES commonly used for in wireless security?
AES is commonly used in wireless security to establish a secure authentication mode between routers and clients for cryptography.
56. What is the Riddles algorithm used for?
The Riddles algorithm is widely used in securing WIFI endpoints, SSLTL S encryption, and file encryption.
57. What are the advantages of AES over DPSK?
AES has advantages in key length, block size, and complexity compared to DPSK. DPSK has a fixed number of fronts, while AES has a variable number of rounds based on the key length.
AES is considered simpler than DPSK but faster in encryption and decryption.
58. What is Private message encryption?
Private message encryption emerged as a solution to the key exchange issue with symmetric algorithms.
59. What is DSLG used for?
DSLG has been developed to address the critical exchange issue with symmetric algorithms.
60. How do digital signatures work?
Digital signatures authenticate and verify documents and data, preventing tampering and digital modification. They work on the public critical cryptography architecture, passing the original plaintext message to a hash function to create a digest.
The message is then encrypted using the sender’s private key and decrypted using the public key.
The message is then interpreted and compared to the digest to verify data integrity.
61. What are the two primary algorithms for implementing digital signatures?
The two primary algorithms for implementing digital signatures are the RSL and DPSK algorithms.
62. What is the DPSK algorithm?
The DPSK algorithm is a FIPA standard proposed in 1991 and globally standardised in 1994 by the National Institute of Standards and Technology.
It uses mathematical functions to create a digital signature consisting of two 160-bit numbers generated from message digests and the private key.
63. What are the benefits of using DPSK?
DPSK offers three benefits: message authentication, integrity verification, and non-repudiation.
65. What is the difference between DES and AES?
AES is a direct successor to DES, providing key length, block size, and complexity advantages. DES has a fixed number of rounds, while AES has a variable number based on the key length.
66. What is the difference between the RSA and DSL algorithms?
The DSL algorithm is a FIPA standard proposed in 1991 and globally standardised in 1994 by the National Institute of Standards and Technology. It uses mathematical functions to create a digital signature consisting of two 160-bit numbers generated from message digests and the private key.
The RSA algorithm, on the other hand, is more difficult to forge and requires proper implementation.
67. What is the DSA algorithm?
The DSA algorithm is a robust and efficient signature verification method that uses a hash function to generate a digest H from a plain text message. It is patented, but NISD has made it available worldwide royalty-free.
68. What is the RSA algorithm?
The RSA algorithm is a cryptographic technique used for encryption and decryption of data.
It is beneficial for securing private information before being transmitted across communication challenges.
69. How does the RSA algorithm work?
The RSA algorithm generates a key pair consisting of a private key and a public key. The private key is kept secret and used for decryption, while the public key is shared and used for encryption.
Data is encrypted using the receiver’s public key and decrypted using the receiver’s private key.
70. What is the difference between RSA and DSA?
RSA is a symmetric encryption algorithm used for general data encryption and decryption, while DSA is an asymmetric algorithm used for signature verification.
DSA uses a hash function to generate a digest H from a plain text message, which is then encrypted using the sender’s private key.
71. What is the purpose of the MD5 algorithm?
The MD5 algorithm is a one-way cryptographic function designed for secure cryptographic hashing to authenticate digital signatures. It is used to verify the integrity of data and show the sender.
72. What are the advantages of using RSA cryptography over other signature verification algorithms?
RSA cryptography offers several advantages over other signature verification algorithms, such as faster key generation, less storage space, and more robust security.
It also allows the receiver to use their public key for decryption, preventing the need for sharing a secret key.
73. What is RSA cryptography?
RSA cryptography is a method for encrypting and decrypting private information before being transmitted across communication challenges. It uses critical generation encryption and decryption functions.
The process starts with creating data and generating the key pair, which is then used for encryption and decryption.
74. What is the MD5 algorithm designed for?
The MD5 algorithm is designed to produce a 128-bit digest that appears random and is cryptographically secure.
The hash function must meet two requirements: it cannot be generated by an attacker and cannot produce two messages with the same hash value.
75. What is the plain-text requirement for the MD5 algorithm?
The plain text must be compatible with the hash function, with the size of the input string being 64-bit short of a multiple of 512.
76. What are the advantages of using the MD5 algorithm for password storage?
MD5 algorithm has a relatively low memory footprint and is easier to run on older hardware, making it suitable for storing user credentials on servers. Additionally, hashing requires less computational resources compared to other hash algorithms.
77. What are the requirements for the hash function in MD5?
The hash function must meet two requirements: it cannot be generated by an attacker and cannot produce two messages with the same hash value.
78. What is the output of the third iteration of MD5?
The output of the third iteration is added to a constant value derived from the continuous array k, which has 64 elements.
The next step involves a circular shift to create a unique digest for each input, with the output added to the buffer B and stored in the output register.
79. What is the difference between MD5 and other hash algorithms?
MD5 is a non-linear process that uses a 32-bit digest to generate a single output.
This method is more straightforward to compare and maintains computational complexity, making it more secure than other hash algorithms.
However, it exposes passwords to hackers and malicious actors, as they are stored in plain text format.
80. What are secure hash algorithms?
Secure hash algorithms are a family of cryptographic hash functions published by the National Institute of Standards and Technology and the National Security Agency.
Cryptography is an indispensable field of study for anyone pursuing cybersecurity. Cryptography uses mathematical algorithms and protocols to secure sensitive data while communicating safely over networks, and understanding its fundamental principles is vitally important in protecting personal privacy online.
This blog presents cryptography and network security lab viva questions and answers,introducingcryptography and network security interview questions with answers, from essential topics like encryption and decryption to more complex subjects such as hash functions and public key cryptography.
Cryptography is an ever-evolving field; new techniques and protocols emerge constantly, necessitating you to stay current on what’s new while expanding your knowledge base.
Therefore, stay aware of any new developments by keeping abreast of cryptographic news as it happens and keep learning!
Overall, this blog’s cryptography and network security viva questionsare valuable for anyone preparing to attend a cryptography interview.
By studying and practising these concepts, you can increase your odds of success while making a meaningful contribution to cybersecurity.
Cryptography Course Price
Sindhuja
Author