Prepare Interview

Mock Exams

Make Homepage

The Best LIVE Mock Interview - You should go through before Interview

## Freshers / Beginner level questions & answers

### Ques 1. Define Cryptography and its benefits?

The Cryptography is actually a method of securing communications through some protocols in order to make the information secure or understood able only by the sender as well as the receiver. Earlier this strategy was based on mathematical theories and computer science. However, with improvement in technology, it is presently based on some vast protocols that are difficult to crack. Thus information security, as well as authenticity can always be ensured and it’s the leading benefit of Cryptography.

### Ques 2. What are the few major applications of cryptography in the modern world?

There are lots of benefits of cryptography in the modern world and a few of them are:

1. Chip-based payment cards
2. Computer and other passwords
3. E-commerce
4. Defense communications
5. Digital Currencies
6. Designing protocols
7. Data authenticity

### Ques 3. What is decryption? What is its need?

Cryptography has two important modules and they are encryption and second is decryption.

Encryption is basically an approach that converts information into secret codes. It is also known as encoding. It is done to make the information secure.

On the other side decryption is a process that is opposite to it i.e. converting the coded information back to its actual form. Only the receiver knows the protocols to decode that information.

### Ques 4. What are the major threats to any data or information for which it needs cryptography?

There are a lot of threats in fact and you might have no idea that with respect to advancement in technology, the reverse effect of the same has also enhanced all over the world.

Hackers can steal data and any sensitive information upon leaking can create issues for the business, a government, financial institution as well as for a person individually.

The leak of confidential information can put the entire organization at risk.

Therefore data needs to be secured.

### Ques 5. What do you mean by Secret Key Cryptography and Public Key Cryptography? How they are different from one another

Both these are the algorithms of encryption and contribute to data security.

Secret Key Cryptography can be used for both encryptions as well as decryption. It is also considered an asymmetric approach and contains only one key.

On the other hand, Public Key cryptography is basically an asymmetric approach.

There are two keys in this approach and one is basically the public key and any user can access the information. The other key is private and can only be accessed by the administrator.

### Ques 6. How Hash Functions are different from Public Key Cryptography and Secret Key Cryptography?

They are basically considered single-way encryption.

Unlike Public Key Cryptography and Secret Key Cryptography, they don’t have any key in them and their prime function is to make sure that a file has reached its destination without any modification.

### Ques 7. What type of information can be secured with Cryptography?

Well, there is no strict upper limit on that. Any information that needs some privacy can be encrypted with this approach.

However, in the present scenario, most of the information belongs to secret operations, business data, defense applications, and lots more.

Cryptography is an approach that can encode both digital, as well as analog information and data without facing any issue.

### Ques 8. In case a Cryptography tool is not available and you need to send secret information, would you proceed or wait till the presence of the tool?

It all depends on the security of the network itself in such a case. If the network is secure, the information can be shared.

In case not, I will probably wait for the Cryptography tool to be active. This is because any information without proper encryption can easily be leaked

### Ques 9. What exactly do you know about RSA?

It is basically a public key cryptography approach that is based on encryption, as well as authentication.

It was first used in the year 1977 and is based on prime number logic. It is basically a fast approach that can handle multiple operations at a time. However, if the key size is small, it generally performs its operation slower.

### Ques 10. Name the elements of a cryptography tool?

There are basically three important elements.

The first is the sender which in fact also encrypts the information in a secured form.

The other is the receiver where information is received and decoded.

The third is the channel in fact which connects both sender and receiver.

Most of the attacks for data-stealing are made on a channel only. This is the reason that why data or information on it always remains in a coded form.

### Ques 11. Explain the difference between a crypter and a cryptographer.

A cryptographer is somebody who does cryptography, and that implies planning or dissecting any part of encryption.

A crypter, then again, is an individual attempting to guilefully camouflage some malware as anything different like a helpful program, so that it can be spread undetected.

### Ques 12. What are the significant dangers to any information or data that needs cryptography?

There are a ton of dangers indeed, and you may have no clue about that; as for headway in innovation, the converse impact of the equivalent has additionally improved everywhere.

Programmers can take information, and any delicate data after spilling can make issues for the business, an administration, monetary organization just as for an individual exclusively. The break of private data can put the whole association in danger. In this manner, information should be secured.

## Intermediate / 1 to 5 years experienced level questions & answers

### Ques 13. what are the prime objectives of modern cryptography?

There are four prime objectives and they are:

1. Confidentiality
2. Non-repudiation
3. Authenticity
4. Integrity

### Ques 14. What do you know about cryptosystems? What is its significance?

These are basically some of the important protocols that assure all the objectives of data encryption have been met.

Regulation of human behavior is also an important module in cryptosystems in which it assures that accounts have been logged off from systems, not in use, passwords that are difficult to guess, maintain the privacy of any information or data that is highly sensitive.

### Ques 15. What is the role of Shift Register Cascades in Cryptography?

There are stages when binary bits are needed and this can be done with the help of Linear Feedback Shift Registers.

Registers are required to be connected in such a manner that one register controls the clock for the previous. This type of interconnection is generally regarded as Shift Register Cascades. It shows how the behavior of one register depends on the other.

### Ques 16. What is the Digital Signature Algorithm?

The digital signature algorithm was implemented for the authentication of data in the year 1994.

It offers quick signature generation and in addition to this, it ensures better verification of information it is dealing with.

It is actually based on computing discrete algorithms and its security actually depends on the size of the key. It can handle key size up to 1024 bits presently.

### Ques 17. Name the two Signature schemes that are used in Cryptography?

• Special Signature scheme
• Blind Signature Scheme

### Ques 18. What is the One-Way function?

One-Way function is basically an approach that is used to assure faster information processing for cryptography when data needs to be sent in one way only and no reverse action is possible.

Functions can be computed in one direction within a very short span of time but performing the opposite task can be extremely daunting.

### Ques 19. What exactly is the other name of Checksum in Cryptography?

It is called a Message Authentication Code or MAC.

It can be categorized as block chipper based, unconditionally secure, stream cipher based, as well as hash function based.

### Ques 20. What is Quantum Cryptography?

When it comes to exchanging secure information over an insecure channel, this approach is considered.

It all depends on the nature of photons in which the third polarization is focused. It can easily be trusted when it comes to exchanging the Secret keys without facing any issue.

Quantum Cryptography is useful when an organization has to send information outside its network without compromising its security and authenticity. It is having a lot of applications in secret and defense operations.

### Ques 21. Is Cryptography a legal approach or not?

Cryptography is basically an approach that is used for data security.

However, it has been seen that it can also have a lot of cons associated with it. Only governmental agencies and authorized organizations are allowed to use it in some parts of the world and thus it is not accepted as a legal approach everywhere.

### Ques 22. What is the basic principle of Cryptography?

The basic principle of this approach is nothing but to write and solve codes so that information security can be enhanced and that automatically leads to privacy

### Ques 23. Name the properties of Interactive proof that are useful in Cryptography according to you?

1. Zero Knowledge
2. Soundness
3. Completeness

### Ques 24. Define Salting.

Salting is the process of obfuscating passwords by introducing an arbitrary value to them after they’ve been hashed.

### Ques 25. What is the reason behind the use of salting in cryptography?

Since individuals will generally reuse passwords, a hacker with a rundown of normal passwords or taken ones secures his position simpler. A Salt is an arbitrarily created number, yet it decreases the chance of being in a predetermined table.

### Ques 26. Describe a session key?

A session key ordinarily gets correspondence between two groups.

It is sent with each message among customer and server, client and customer, or two PCs. They are scrambled with the recipient’s public key.

## Experienced / Expert level questions & answers

### Ques 27. What exactly do you know about SAFER? What is its abbreviation?

SAFER stands for Secure and Fast Encryption Routine and is basically a block chipper.

It has a 64-bit block size and is a byte-oriented algorithm that is widely used. Its encryption and decryption procedures are highly secure and have 10 rounds out of which 6 can be used freely. This technology has wide application in digital payment cards.

### Ques 28. What is the Fast Data Encipherment Algorithm?

It is basically a cryptosystem that has a 64-bit block size.

Its prime aim is to assure the performance of the software in which it is used. However, due to its insecure approach, it is not so common in the present scenario.

### Ques 29. What is the difference between Block chippers and Stream Chippers?

Both Block Chippers and Stream Chippers have a similar objective but both operations in a different manner.

Stream Chippers are faster when compared to block.

Block chippers generally operate on the data which is large in size while on the other side, Stream chippers are considered when small units of text are to be considered.

Stream Chipper seems complex in handling the assigned tasks while the Blok chipper is best in performing the same.

In addition to this, block chipper results always error-free and can be trusted for the long run.

### Ques 30. How you will generate a sequence of binary bits in cryptography?

This can be done with the help of the Linear Feedback Shift Register.

It can perform this task reliably. The register is loaded with some cells that can easily be initialized through a vector which in most cases is nothing but a secret key. At every clocking instant, it is possible to regulate the behavior of the register and thus best outcomes can be assured. It shifts its content to right one by one till every bit is placed on the left side.

### Ques 31. What do you mean by DNA computing?

It is nothing but a collection of random strands of DNA that can be combined to find the solution to a specific problem.

It works perfectly on both basic and as well as large-scale strands.

The other name of DNA computing is Molecular computing. By parallel search, it aims to solve some of the very complex problems that can declare their presence in the cryptography approach.

### Ques 32. When will you use a shrinking generator in Cryptography?

When a direct interaction is required in the outputs of Linear Feedback Shift Registers, this can be used.

It is actually scalable up to a great extent and has excellent securing properties that make it a good approach to trust.

The shrinking generator can also be used to analyze how to secure information is. It can also be used to imposing a limit on the size of data that needs to be controlled.

### Ques 33. What do you know about the Vernam Chipper?

In case the bits are generated randomly, this is the chipper that is used for controlling their actions.

It combines them with plain text reliably and the output is regarded as hypertext. Thus a very secure environment can be assured and the best part is it’s not very difficult to use this approach.

### Ques 34. What do you know about a Compression Function in Cryptography?

It is basically an approach that is used for securing the information reliably.

A Compression function takes input in the form of a fixed length of bits and the outcome is shorter. A method is generally divided into smaller blocks for its easy authentication and implementation in the cycle. Each small block is then processed and the output is the combination of bits and hash value.

### Ques 35. Is it possible to combine cryptography with any other data security approach?

Yes, it’s possible to do so.

### Ques 36. Describe Rainbow Tables.

Rainbow tables are pre-registered tables that comprise hash numerals or digits similar to plaintext codes.

Also, these can be utilized by programmers to match taken hashes to likely passwords. It permits passwords or codes to be broken significantly quicker however requires high stockpiling capacities.

### Ques 37. In the Realm of cryptography, define FEAL.

A block cipher that has been intended to be proficient in hardware and software is known as FEAL Algorithm.

### Ques 38. Define Trapdoor Functions.

Trapdoor Functions are such works that can undoubtedly be tackled in a single course; however, they are very tedious and troublesome in the other bearing.

Playing out the opposite computation easily is conceivable yet requires a particular cycle.

### Ques 39. In cryptography, what is meant by Blowfish?

When altering keys, a blowfish is indeed an asymmetric block key encryption that is efficient yet demands pre-processing equivalent.

### Ques 40. Why is SSL encrypting insufficient?

SSL only secures your information while it is in transit. It does not safeguard data after it reaches the recipient. SSL also does not encrypt your information. When it comes to processing metadata, this might be a flaw. This enables your prospective hacker to create a client profile and consider network layouts.