Digital Certificate and Digital Signature :
Digital certificate is an electronic identity provided to an entity by a competent authority or a certification authority. It is a unique public key provided to each entity for establishing the entity’s authenticity
Just like a passport, a digital certificate provides identifying information and is forgery resistant and can be verified because it was issued by an official, trusted agency. The certificate contains the name of the certificate holder, a serial number, expiration dates, a copy of the certificate holder’s public key (used for encrypting messages and digital signatures) and the digital signature of the certificate-issuing authority (CA) so that a recipient can verify that the certificate is real.
To provide evidence that a certificate is genuine and valid, it is digitally signed by a root certificate belonging to a trusted certificate authority. Operating systems and browsers maintain lists of trusted CA root certificates. So they can easily verify certificates that the CAs have issued and signed. When PKI is deployed internally, digital certificates can be self-signed.
Digital signatures: As per Sec 2(1) (p) of the Act a digital signature means an authentication of any electronic record by a subscriber by means of an authentication of any electronic record by a subscriber by means of an electronic method or procedure in accordance with the other provisions of the Act
A digital signature is a mathematical scheme for demonstrating the authenticity of a digital message or documents. A valid digital signature gives a recipient reason to believe that the message was created by a known sender, that the sender cannot deny having sent the message (authentication and non-repudiation), and that the message was not altered in transit (integrity).
Digital signatures are a standard element of most cryptographic protocol suites, and are commonly used for software distribution, financial transactions, and in other cases where it is important to detect forgery or tampering.