Digital signatures are based on digital certificates. Digital certificates are verifiers of identity issued by a trusted third party, which is known as a Certification Authority (CA). This works similarly to the use of standard identity documents in a non-electronic environment. For example, a trusted third party such as a
government entity or employer issues identity documents — such as driver’s licenses, passports, and employee ID cards — on which others rely to verify that a person is whom he or she claims to be.