CRYPTOGRAPHY COMPUTER SCIENCE A digital signature provides f

CRYPTOGRAPHY, COMPUTER SCIENCE

A digital signature provides for data integrity and a MAC provides for data integrity. Why does a signature also provides for non-repudiation while a MAC does not?

Solution

Explanation:

Answer:

Firstly we will see what is \"Cryptography\". Cryptography is basically an art through which two parties communicate to one another in presence of third party so that
secure communication takes place between the two parties. Cryptography is about constructing and analyzing protocols that prevent third parties or the public from
reading private messages. The main aim of cryptography is to maintain:
1. Confidentiality
2. Data Integrity
3. Authentication
4. Non-Repudiation

There are various techniques through which we can implement cryptography. Few are Digital Signature, MAC and hash. Here we will see about digital signature and MAC.
1. Digital Signature: A digital signature is a technique which maintains the authenticity of digital messages or documents. A valid digital signature
gives a recipient reason to believe that the message was created by a known sender (authentication), that the sender cannot deny having sent the message
(non-repudiation), and that the message was not altered in transit (integrity).
Digital Signature provides non repudiation because it is created with the help of private key and verified with the corresponding public key of an
asymmetric key-pair. The owner of the private key can create this signature and normally anyone knowing the public key can verify it. Hence, digital signature provides
non repudiation with integrity.

2. Message Authentication Code(MAC): It is another technique for cryptography which protects against message forgery by anyone who doesn\'t know
the secret key.This means that the receiver can forge any message integrity and authentication but not non-repudiation as third party could replay earlier messages
authenticated with the same key. So mac provides integrity and authentication but no non repudiation.