Question

digital signature . a) change after every message,b) do not change past ten messages ,c) always remain same ,d) nin of these.​

Answer 1

Answer:

Jason Andress, in The Basics of Information Security (Second Edition), 2014

Digital signatures

Digital signatures are a great example of where the hash function is used. Digital signatures allow us to sign a message in order to enable detection of changes to the message contents, to ensure that the message was legitimately sent by the expected party, and to prevent the sender from denying that he or she sent the message, known as nonrepudiation. To digitally sign a message, the sender would generate a hash of the message, and then use his private key to encrypt the hash, thus generating a digital signature. The sender would then send the digital signature along with the message, usually by appending it to the message itself.

When the message arrives at the receiving end, the receiver would use the sender’s public key to decrypt the digital signature, thus restoring the original hash of the message. The receiver can then verify the integrity of the message by hashing the message again and comparing the two hashes. Although this may sound like a considerable amount of work to verify the integrity of the message, it is often done by a software application of some kind and the process typically is largely invisible to the end user. A digital signature is considered legally binding and if it is lost or stolen must be revoked.