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Digital Certificates and Signatures

A digital signature and a digital certificate are both security measures, but are different in the way that they are implemented. 

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Digital Signature

digital signature is a mechanism that is used to verify that a particular digital document, message or transaction is authentic. It provides a receiver the guarantee that the message was actually generated by the sender and it was not modified by a third party.

A digital signature is an electronic, encrypted stamp of authentication on digital data. The  signature confirms that the information originated from the signer and has not been altered.

The signature is created when the message is sent, using a private encryption key. This is the opposite to normal PKE. The signature is then paired with a public key and sent with the message. When the message run through the public key the result should match the signature.

If they don’t match then the message has been altered en route. This shows that the message has been intercepted and compromised.

Digital signature - Wikipedia

Digital Certificates

Digital certificates are the attachment to an electronic message used for security purposes.

A certificate is used to verify that a user sending a message is who they claim to be and to bind their public key to them. Certificates can only be issued by certain trusted entities including Google, Symantec, and Comodo.

The “lock” icon in your browser shows the status of the certificate. The lock indicates that the website is backed by a digital certificate and is a genuine website and is not a fake set up by criminals.