Implicit certificates

Traditional certificates contain identification data, a public key, and a digital signature that binds the public key to the user’s identification data. This signature also verifies that an authority (or trusted third party) accepts this binding. The public key and digital signature are distinct data elements of these traditional certificates.

An implicit certificate also contains identification data, but the public key and digital signature can be considered to be combined into a single element–the public key reconstruction data. The public key reconstruction data allows the recipient of an implicit certificate to derive the public key of the other party. This derivation substantially reduces the amount of data that needs to be sent to the recipient, because the digital signature no longer needs to be sent. The introduction of implicit certificates has resulted in referring to traditional certificates as explicit certificates.

Advantages of implicit certificates

The key advantages of implicit certificates over explicit certificates are that implicit certificates are smaller and faster.

Implicit certificates are smaller than explicit certificates because no digital signature is sent with the certificate.

It takes less work to extract the public key of the sender than to verify a digital signature. Therefore, implicit certificates are faster (that is, require less computing time) than explicit certificates.

Last modified: 2015-03-31



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