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Consider the following two statements:

  1. A hash function (these are often used for computing digital signatures) is an injective function.
  2. A. encryption technique such as DES performs a permutation on the elements of its input alphabet.

Which one of the following options is valid for the above two statements?

  1. Both are false
  2. Statement (i) is true and the other is false
  3. Statement (ii) is true and the other is false
  4. Both are true

3 Answers

Best answer
26 votes
26 votes

Answer is C.

i. Hash function is not one one or injective. It is many to one.

ii. True. Uses P-Box permutation.

edited by
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Option (i) Here some asymmetrical algorithms where we apply Hashing (Hashing is a method used to verify data integrity).

1. RSA - named after Rivest, Shamir, and Adleman (investor)

2. Diffie-Hellman (DH)

3. ElGamal - based on the DH echange 

4.Digital Signature Algorithm (DSA)- created by NSA 

5. Eliptic Curve Cryptography (ECC)

Here some most popular Hashing types

1. MD5 (Message Digiest 5)

2. SHA 1

3. SHA 2

4. SHA 3

So we can correctly say it is not injective (one to one).

Option (ii) DES (Digital Encryption Standard) is part of symmetric key algorithm where we use same key to encrypt the data and decrypt the data. so calculating we perform permutation.

Statement (ii) is true and the other is false

 

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ans d)
Answer:

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