Definition
1. Call Appearance (CA) telecommunication term
2. Certification Authority (CA)
Complete Definition
1. Call Appearance (CA) telecommunication term
2. Certificate Authority
A certificate authority (CA) is an authority in a network that issues and manages security credentials and public keys for message encryption. As part of a public key infrastructure (PKI), a CA checks with a registration authority (RA) to verify information provided by the requestor of a digital certificate. If the RA verifies the requestor's information, the CA can then issue a certificate.
Depending on the public key infrastructure implementation, the certificate includes the owner's public key, the expiration date of the certificate, the owner's name, and other information about the public key owner.
If the user trusts the CA and can verify the CA's signature, then they can also verify that a certain public key does indeed belong to whoever is identified in the certificate. If the CA can be subverted, then the security of the entire system is lost.
CA Wikipedia Definition
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