A digital certificate is a document comprising various properties of the certificate holder. These certificates are standard-compliant, and, in the case of HF, this is the X.509 standard.

Here are a few brief details regarding certificates:

• What is in a certificate? A certificate is like an identity card, and includes certificate data that consists of the following:
  • Algorithm information (such as SHA256)
  • Issuer information, including the validity of the certificate (time)
  • Subject information, including the following:
    • Subject details, such as the organization unit
    • Subject public key and signature algorithm details
• The subject of a certificate (the user or node) can use that certificate to prove their identity.
• To prove their identity, the subject can use a private key to sign any communication (transaction and suchlike) that is sent to the blockchain network. A subject's public key is in the certificate itself. However, the subject's private key is secret and private.
• All the information contained in the certificate is encrypted in such a way that any change to it will mark the certificate as invalid.
• The subject signs using their private key and uses this certificate to prove their identity. As other parties trust the identity provider, also known as the CA, the interacting party can trust the subject. Parties trust the CA and believe that the certificate shown by the subject has not been tampered with.