Consider the following statements:

A digital signature is
1. an electronic record that identifies the certifying authority issuing it.
2. used to serve as a proof of identity of an individual to access information or serve on Internet.
3. an electronic method of signing an electronic document and ensuring that the original content is unchanged.

Which of the statements given above is/are correct?

The correct answer is 3 only.

Let us analyze each statement regarding a digital signature to understand why statement 3 is correct while statements 1 and 2 are incorrect:

1. Statement 1: "an electronic record that identifies the certifying authority issuing it."
This statement describes a Digital Signature Certificate (DSC) rather than a digital signature itself. A Digital Signature Certificate is an electronic document/record issued by a Certifying Authority (CA) to verify the identity of the holder, containing information about the user's identity and the issuing authority. Therefore, Statement 1 is incorrect when applied to a digital signature.

2. Statement 2: "used to serve as a proof of identity of an individual to access information or serve on Internet."
Serving as a proof of identity to gain access to services or information on the internet is also the function of a Digital Signature Certificate (DSC) or identity credential (like an digital ID / SSL certificate), not the mathematical/electronic mechanism of a digital signature itself. Hence, Statement 2 is incorrect.

3. Statement 3: "an electronic method of signing an electronic document and ensuring that the original content is unchanged."
A digital signature is a mathematical scheme/technique used to validate the authenticity and integrity of a digital message or document. It ensures non-repudiation and guarantees that the original content has not been altered or tampered with since it was signed. Thus, Statement 3 is correct.

Therefore, only statement 3 is correct.