Basic Concepts of Cryptography Worksheet Overview: Review the questions below an

Question

Basic Concepts of Cryptography Worksheet Overview: Review the questions below and provide a paragraph or two response. 1. Describe an algorithm that could be used as a hashing encryption algorithm. What does it look like? 2. Discuss the specific actions that can be used to encrypt data. 3. What are the key distinctions between an encryption algorithm and a key? 4. What is a potential drawback of symmetric encryption? 5. What makes public key encryption potentially so secure? 6. Considering that hashing encryption is one-way and the hash is never decrypted, what makes hashing encryption a useful security technique?

Explanation / Answer

Ans 1. Hashing encryption alogorithms uses has value or hash codes for its cryptographical data.There are various popular hash functions such as Message Digest, Secured Hash Function(SHA) -0, 1, 2 and 3, RIPEMD, Whirlpool.

Let us discuss SHA 1 algorithm in some detail as it is the most popular one which is employed in various applications and also in SSL layer protocols which provides good amunt of internet privacy.

Following are the steps involved in SHA-1

Step 1 : Bits padding

Bits are padded so that message length is 64 bits less than closest multiple of 512, depending on origianal message length.

2.Append length:

padded message is appendend with 64 bit binary which stores information about original message length.

3. Make blocks of 512 bits length.

4. Chaining variables are initialized A to E

5. Make copies (a-e) of chaining variable (A- E )

6. Make 16 subblocks of 32 bits length out of 512 bit block under process.

7 SHA has total 80 iterations which has 4 rounds of 20 steps each. we have a constant K(t) as follows

Round 1 :t=1 to 19

Round 2 :t=20 to 39

Round 3 :t=40 to 59

Round 3 :t=60 to 79)

where abcde=(e+Process P + S5(a)+W[t]+K[t]),a,S30(b),c,d is processed among five registers for every variable a-e

P is logical operation

S circular left shift

W[t] current 32 bit block

K[t] any of the five additive constant

8. This will output word buffers

Ans 2. Encription key or algorithm or both are used to encrypt data so it cannot be viewed in its normal form by unauthorised access.
There are two ways of encryption: Symmetric Encryption (in which single key is used to encrypt and decreypting data) aand Asymmetric encryption(Two keys one public and one private are used)
> Data is taken for encryption
> it is encrypted using key and algorithm used.
> Data is end to intended user. key is send using othe message for safety.
> At user point, it is decrypted using sma ekey or other key based on encryption technique.

Ans 3.

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