# Cryptography Algorithm Interview Preparation Guide **Download PDF** Add New Question

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Cryptography Algorithm frequently Asked Questions in various Cryptography Algorithm job Interviews by interviewer. Get preparation of Cryptography Algorithm job interview

## 9 Cryptography Algorithm Questions and Answers:

### 1 :: What are MD2, MD4, and MD5?

MD2, MD4 and MD5 are 128 bit hashing algorithms

### 2 :: What is RC5?

RC5 is the coding technique through which IR remote button

keycode are coded and transmitted to the receiver......

keycode are coded and transmitted to the receiver......

### 3 :: What is RC4?

RC4 is a symmentric key, cryptographic algorithm developed

by Ron Rivest. It uses stream cipher to create variable

size keys.

by Ron Rivest. It uses stream cipher to create variable

size keys.

### 4 :: What is Diffie-Hellman?

It is a method by which a key can be securely shared by two

users without any actual exchange.

users without any actual exchange.

### 5 :: What is the AES?

1)AES is ADVANCE ENCRYPTION STANDARD its is a symmetric key

block cipher .

2)AES has number of rounds each round makes a number of

transformations on a state and uses a round key derived

from encryption key.

3) number of block depends upon block size

4)an encryption of a block starts with a transformation

AddRoundkey this is followed by and odd number of regular

rounds and ends with a special final round.

5)the final round helps in decryption.

6) basic principle used is substitution permutation network.

7)aes has block size of 128 bits and key size of 128 192 or

256 bits

8)rounds are :

1)addroundkey-each byte of the state is combined with round

key using bitwise X-OR.

2)subbytes- each byte is replaced by another byte according

to lookup table

3)shiftRow-a transposition step where each row of the state

is shifted cyclically a certain number of steps

4)mix column-combination of 4 bytes takes palce in each column

5)final round

block cipher .

2)AES has number of rounds each round makes a number of

transformations on a state and uses a round key derived

from encryption key.

3) number of block depends upon block size

4)an encryption of a block starts with a transformation

AddRoundkey this is followed by and odd number of regular

rounds and ends with a special final round.

5)the final round helps in decryption.

6) basic principle used is substitution permutation network.

7)aes has block size of 128 bits and key size of 128 192 or

256 bits

8)rounds are :

1)addroundkey-each byte of the state is combined with round

key using bitwise X-OR.

2)subbytes- each byte is replaced by another byte according

to lookup table

3)shiftRow-a transposition step where each row of the state

is shifted cyclically a certain number of steps

4)mix column-combination of 4 bytes takes palce in each column

5)final round

### 6 :: What is random number generation?

a random no. is a number used for checking freshness of

session. It is used to avoid replay attack

session. It is used to avoid replay attack

### 7 :: What are SHA and SHA-1?

SHA is a secure hash algorithm developed by national

institute of standard technology

SHA-1 is a type of SHA

message digest size of SHA 1 Is 160 bits and

message size is < 2^64

it uses block cipher

sha is a digital signature algorithm

institute of standard technology

SHA-1 is a type of SHA

message digest size of SHA 1 Is 160 bits and

message size is < 2^64

it uses block cipher

sha is a digital signature algorithm

### 8 :: What are secret sharing schemes?

deffie hellman

### 9 :: How does one use DES securely?

If we use Triple DES it may be secure