a Explain what message integrity is and how an electronic si

a) Explain what message integrity is and how an electronic signature provides message integrity. B) Explain what non-repudiation is and how an electronic signature achieves non-repudiation? c) demonstrate an understanding of the process as shown on #3-20 of the lecture slides.

Electronic Signature: Using Asymmetric Key Encryption for Authentication Sender Receiver Bob Alice A Compute Message Digest signature Compute Message Digest Compute Verify Signature Signature Alice\'s Public Key Alice\'s Private Key Electronic signatures provide authentication, message integrity, and non-repudiation

Solution

A) Message Integrity means that ensures that the contents of a message have not been tampered with and altered during transmission.electronic signature provides message integrity as we cannot get the same signature if the message is changed. Because if the message is changed, we will not get a same electronic signature as previous and message integrity gets violated.

B) Nonrepudiation is the assurance that someone cannot deny something. Typically, nonrepudiation refers to the ability to ensure that a party to a contract or a communication cannot deny the authenticity of their signature on a document or the sending of a message that they originated.since an electronic signature can only be created by one person, to ensure that a person cannot later deny that they furnished the signature.

So in this way, electronic signature provide message integrity and non-repudiation.

C) Electronic signature provides authentication(authenticate the sources of messages means who is sending the message), message integrity(content of a message is altered or not) and Nonrepudiation (source can\'t deny that he sent the message).

Alice has to send a message to bob. From given message, a Message digest is computed.A message digest is a cryptographic hash function containing a string of digits created by a one-way hashing formula.Many message digest functions like MD2, MD4, MD5, SHA is used for this purpose. Now that message digest is encrypted using Alice private key to ensure authentication and send it to Bob.

Now bob receives the encrypted signature and original message. Bob decode encrypted signature with Alice public key. from here he gets message digest. This message digest is compared with computed message digest(Bob compute it from original message). if they are the same mean that message integrity is preserved.