Statement 3 is correct. A digital signature is a cryptographic mechanism used to verify the authenticity and integrity of a digital document or message. It ensures that the content has not been altered after it was signed and confirms the identity of the signer. This process provides assurance that the data originated from a specific sender and has remained unchanged during transit.
Statement 1 is incorrect. This statement describes a Digital Signature Certificate (DSC), not a digital signature itself. A DSC is an electronic document issued by a Certifying Authority (CA) that binds a public key to an identity. It contains identifying information about the certificate holder and the issuing CA, serving as a digital identity. A digital signature, conversely, is the cryptographic output generated when a private key is applied to data.
Statement 2 is incorrect. While digital signatures are an integral part of secure online interactions, their primary function is to ensure the integrity and authenticity of data, not solely to serve as a proof of identity for accessing server information. The broader mechanism for proving an individual's identity to access servers typically involves digital certificates (which contain identity information) and secure protocols like SSL/TLS, where digital signatures play a role in securing the communication channel and verifying the certificate's validity, but not as the sole proof of identity for server access.
Therefore, options 1, 2, and 4 are incorrect as only statement 3 accurately defines a digital signature.