5: Digital Signature

Question 1

What is a Digital Signature?

Answer 1

Digital Signature is a process wherein a digital code is attached to an electronically transmitted document to verify its contents and the sender’s identity.

Question 2

How is a digital signature created

Answer 2

1- Creating a hash value or message digest of a given message
2- Encryption of the hash value or message digest with the private key of the sender.

Question 3

What is the other name of a hash

Answer 3

A message digest.

It must be noted that the hash value will be unique for each message.

Question 4

What is the purpose of hash value

Answer 4

To validate the integrity of the message

Question 5

How a message flows from sender A to Sender B using a digital signature

Answer 5

1- Creating a hash value or message digest of a sender A’s given message
2- Encryption of the hash value or message digest with the private key of the sender A
3- Message digest is sent via an email to sender B
4- System calculate Hash message, and decrypt Message using Sender A’s public key

Question 6

What a digital signature ensures

Answer 6

Integrity
Authentication
Non-repudiation

Question 7

Integrity

Answer 7

A message has not been tampered

Question 8

Authentication

Answer 8

A message has been actually sent by sender

Question 9

Non-repudiation

Answer 9

Sender cannot later deny about sending the message

Question 10

Can digital signature ensure confidentiality

Answer 10

No , it doesn’t, because digital signature only encrypts the hash of the message and not the message itself.

Question 11

What key is used for encryption of the hash of the message

Answer 11

The private key of the sender.