Digital Signatures: What They Are & How They Work

Learn why Top Industry Analysts consistently name Okta and Auth0 as the Identity Leader

A digital signature uses a mathematical algorithm to guarantee secure message transmission and authenticity.

Digital signatures use asymmetric cryptography and rely on the PKI (public key infrastructure). A digital signature provides a high level of security and is backed by a standard, publicly trusted, and universal format.

Digital signatures are legally binding, and the PKI can ensure that the message is authentic and retains its integrity. Digital signatures often require the use of a certificate authority (CA), which is a trusted signer for the public key.

Digital signatures can prove the authenticity of a sender. With the use of a matching private key, they make sure that only the intended recipient can read it.

What is a digital signature?

An authentication mechanism, a digital signature is a type of code that is attached to a message by a sender that verifies that they are who they say they are. It associates a particular signer with a specific document.

In this way, a digital signature is unique to the creator and signer of the message. Each signer will have a specific private key that will need to be matched to a corresponding public key for verification and authentication purposes.

A digital signature is a form of cryptography that uses the public key infrastructure, or PKI, to securely transmit messages and authenticate senders. Digital signatures require both a public and a private key to be decrypted. The public key will be signed by a trusted CA and will need to match the private key.

A digital signature can offer a high level of security, as it helps to verify the integrity of messages and authenticity of the sender.

Differences between a signing certificate and certificate authority

A code signing certificate is a digital certificate that is signed by the developer of software or a particular application. This can help to authenticate that the product is real and has not been tampered with or altered. They are not, however, signed by a public certificate authority.

A code signing certificate can be a helpful tool when downloading software or an application from a third-party website or organisation to ensure that it is legitimate and what you are actually trying to access.

A certificate authority, on the other hand, is a highly vetted and publicly trusted entity that signs public keys for the PKI. These keys are widely available and distributed. The CA often signs public keys for the TLS/SSL (Transport Layer Security/ Secure Sockets Layer) protocol, which can authenticate websites to web browsers.

Only the trusted CA can sign digital certificates to validate and authenticate the identity of the user with the matching private key.

Benefits of a digital signature

A digital signature can work the same way as a traditional pen-and-paper signature, offering verification of the identity of the signer. A digital signature offers the following benefits:

  • Heightened security: Digital signatures contain “fingerprint”-type data that is unique and permanently embedded within the document. The coded message contained within the digital signature can identify and verify the signer and link them with the specific recorded document. The PKI encryption verification technology is considered one of the most secure and verifiable standards for identification authentication.  
  • Independent verification and integrity: Highly regarded companies providing digital signatures can hold up through independent verification methods. Message integrity is guaranteed as the digital signature cannot be altered by a third party.  
  • Legal compliance and wide acceptance: Digital signatures are being globally accepted as lega