ZyXEL 35 Guia Do Utilizador

 

 

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A Certification Authority is a trusted third party that verifies the identity of an applicant registering for 

a digital certificate. Once a Certification Authority is satisfied as to the authenticity of an applicant's 

identity, it issues that person a digital certificate binding his or her identity to a public key. (Digital 

certificates are also issued to organizations and devices, but we will focus on people for the purposes 

of this discussion.) 

 

 

An electronic credential that vouches for the holder's identity, a digital certificate has characteristics 

similar to those of a passport – it has identifying information, is forgery-proof, and is issued by a 

trusted third party. Digital certificates are published in on-line directories. Typically, a digital 

certificate contains: 

The user's distinguished name (a unique identifier)   

The issuing Certification Authority's distinguished name   

The user's public key   

The validity period   

The certificate's serial number   

The issuing Certification Authority's digital signature is for verifying the information in the digital 

certificate.  

 

 

A PKI uses asymmetric cryptography to encrypt and decrypt information. In asymmetric cryptography, 

encryption is done by a freely available public key, and decryption is done by a closely guarded 

private key. Although the public and private keys in a particular key pair are mathematically related, it 

is impossible to determine one key from the other. Each key in an asymmetric key pair performs a 

function that only the other can undo. 

 

 

Certification Authorities issue digital certificates that are appropriate to specific purposes or 

applications. For example, in the Government of Canada Public Key Infrastructure, digital certificates 

for data confidentiality are different from those used for digital signatures. Certificate Policies 

describe the rules governing the different uses of these certificates.