Hash Functions and Digital Signatures

Question 1

what are Hash Functions?

Answer 1

Purpose: Generate a unique output value (message digest) from a potentially long message.

Question 2

Applications of hash functions?

Answer 2

Checking integrity and implementing digital signatures.

Question 3

Five basic requirements for a cryptographic hash function

Answer 3

Input can be of any length.
Fixed-length output.
Easy to compute.
One-way (hard to determine input from output).
Collision-free (hard to find two messages with the same hash).

Question 4

Components of Digital signature?

Answer 4

Combine public key cryptography and hashing functions.

Question 4

Some Applications of Hash Algorithms

Answer 4

▪ Integrity verification
* Message integrity
* Digital signatures (integrity + authentication and nonrepudiation)
▪ Committing a secret without telling it
▪ Passwordverification
▪ Trusted timestamping
▪ Blockchain

Question 4

Digital signature infrastructures have two distinct goals

Answer 4

-Assure the recipient that the message came from the claimed sender (non-repudiation).
-Ensure the message was not altered in transit.