ZyXEL 35 Guia Do Utilizador

 

 

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data transmission. 

Asymmetric cryptography solves the key exchange problem by defining an algorithm which uses two 

keys, each of which can be used to encrypt a message. If one key is used to encrypt a message, then 

the other must be used to decrypt it. This makes it possible to receive secure messages by simply 

publishing one key (the public key) and keeping the other secret (the private key).  

 

PKI is acronym of Public Key Infrastructure. A PKI is a comprehensive system of policies, processes, 

and technologies working together to enable users of the Internet to exchange information securely 

and confidentially. Public Key Infrastructures are based on the use of cryptography – the scrambling 

of information by a mathematical formula and a virtual key so that it can only be decoded by an 

authorized party using a related key. 

A PKI uses pairs of cryptographic keys provided by a trusted third party known as a Certification 

Authority (CA). Central to the workings of a PKI, a CA issues digital certificates that positively 

identify the holder's identity. A Certification Authority maintains accessible directories of valid 

certificates, and a list of certificates it has revoked.   

 

PKI brings to the electronic world the security and confidentiality features provided by the physical 

documents, hand-written signatures, sealed envelopes and established trust relationships of traditional, 

paper-based transactions. These features are: 

Confidentiality:  Ensures than only intended recipients can read files.   

Data Integrity:    Ensures that files cannot be changed without detection.   

Authentication:    Ensures that participants in an electronic transaction are who they claim to be.   

Non-repudiation: Prevents participants from denying involvement in an electronic transaction.   

A PKI includes: 

A Certification Authority   

Digital certificates   

Mathematically related key pairs, each comprising a private key and a public key   

These elements work within a formal structure defined by: 

Certificate Policies   

A Certification Practice Statement.