Cryptography interview questions

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Q: Define Cryptography in your own way along with its benefits?
Well, it 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.

Q: Tell us about a 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

Q: 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. 

Q: 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 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. Leak of confidential information can put entire organization at risk. Therefore data needs to be secured. 

Q: 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 in data security. Secret Key Cryptography can be used for both encryption as well as decryption. It is also considered as symmetric 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 administrator. 

Q: How Hash Functions are different from Public Key Cryptography and Secret Key Cryptography?
They are basically considered as 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. 

Q: 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.

Q: In case a Cryptography tool is not available and you need to send a secret information, would you proceed or wait till the presence of tool?
It all depends on the security of 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. 

Q: 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 logics. 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.

Q: Name the elements of a cryptography tool?
There are basically the three important elements. The first is the sender which in fact also encrypts the information in a secured form. The other is 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 channel only. This is the reason that why data or information on it always remains in a coded form.

Q: Can you tell what the prime objectives of modern cryptography are? 
There are four prime objectives and they are:

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

Q: What do you know about the cryptosystems? What is their 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 which are difficult to guess, maintain the privacy of any information or data that is highly sensitive. 

Q: 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 Liner Feedback Shift Registers. Registers are required to be connected in such a manner that one register control 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.

Q: What is Digital Signature Algorithm?
The digital signature algorithm was implemented for 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 algorithm and its security actually depends on the size of the key. It can handle key size up to 1024 bits presently.

Q: Name the two Signature schemes that are used in Cryptography?
Special Signature scheme and blind Signature Scheme

Q: What is One-Way function?
It 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.

Q: What exactly it the other name of Checksum in Cryptography?
It is called as Message Authentication Code or MAC. It can be categorized as block chipper based, unconditionally secure, stream cipherbased, as well as hash functionbased.

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Q: 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 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 with its security and authenticity. It is having a lot of applications in secret and defense operations.

Q: Is Cryptography a legal approach or its 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 the 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.

Q: 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. 

Q: 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 64 bit block size and is a byte-oriented algorithm which 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

Q: What is Fast Data Encipherment Algorithm?
It is basically a cryptosystem that has 64 bit block size. Its prime aim is to assure the performance of software in which it is used. However, due to its insecure approach, it is not so common in the present scenario.

Q: What is the difference between Block chippers and Stream Chipers?
Both has similar objective but both operations in a different manner. Stream Chipers are faster when compared to block. Block chippers generally operates on the data which is large in size while on the other side, Stream chippers are considered when small units of text is to be considered. Stream Chiper seems complex in handling the assigned tasks while the Blok chipper is best in performing the same. In addition to this, block chipper results are always error free and can be trusted for the long run.

Q: Name the properties of Interactive proof that are useful in Cryptography according to you?
1. Zero Knowledge
2. Soundness
3. Completeness

They can simply contribute in enhancing the security of information up to an excellent extent

Q: How you will generate a sequence of binary bits in cryptography?
This can be done with the help of 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 of the 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. 

Q: What do you mean by DNA computing?
It is nothing but a collection of some 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 cryptography approach.

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

Q: What do you know about the Vernam Chipper?
In case the bits are generated randomly, this is the chipper that is used for controlling the actions of them. It combines them with plain text reliably and the output is regarded as chipertext. Thus a very secure environment can be assured and the best part is it’s not very difficult to use this approach.

Q: 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 outcome is shorter. A method is generally divided into the 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.

Q: Is it possible to combine cryptography with any other data security approach?
Yes, it’s possible to do so.


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