What is a Digital ID? A Digital ID (also known as a digital certificate) is a form of electronic credentials for the Internet. Similar to a driver's license, employee ID card, or business license, a Digital ID is issued by a trusted third party to establish the identity of the ID holder. The third party who issues certificates is known as a Certification Authority (CA).
Digital ID technology is based on the theory of public key cryptography. In public key cryptography systems, every entity has two complementary keys--a public key and private key--which function only when they are held together. Public keys are widely distributed to users, while private keys are kept safe and only used by their owner. Any code digitally signed with the publisher's private key, can only be successfully verified using the complementary public key. Another way to look at this is that code successfully verified using the publisher's public key (which is sent along with the digital signature), can only have been digitally signed using the publisher's private key (thus authenticating the source of the code), and has not been tampered with. For more information on public keys and private keys, please see Introduction to Public Key Cryptography).