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Figure 11-1
Certificate issuing and authentication
CA1
Certificate issuing
Certificate verification
…
…
CA2
CAn
Server
certificate
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Digital certificate
A digital certificate is an electronic document issued by a CA to bind a public key with a
certificate subject (an applicant that has obtained a certificate). Information in a digital
certificate includes the applicant name, public key, digital signature of the CA that issues
the digital certificate, and validity period of the digital certificate. A digital certificate
verifies the identities of two communicating parties, improving communication reliability.
A user must obtain the public key certificate of the information sender to decrypt and
authenticate information in the certificate. The user also needs the CA certificate of the
information sender to verify the identity of the information sender.
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Certificate Revocation List (CRL)
A CRL is issued by a CA to specify certificates that have been revoked.
Each certificate has a validity period. A CA can issue a CRL to revoke certificates before
their validity periods expire. The validity period of a certificate specified in the CRL is
shorter than the original validity period of the certificate. If a CA revokes a digital
certificate, the key pair defined in the certificate cannot be used. After a certificate in a
CRL expires, the certificate is deleted from the CRL to shorten the CRL.
Information in a CRL includes the issuer and serial number of each certificate, the issuing
date of the CRL, certificate revocation date, and time when the next CRL will be issued.
Clients use CRLs to check validity of certificates. When verifying a server's digital
certificate, a client checks the CRL. If the certificate is in the CRL, the client considers the
certificate invalid.
Security Mechanisms
SSL provides the following security mechanisms:
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Connection privacy
SSL uses symmetric cryptography to encrypt data. It uses the Rivest-Shamir-Adleman
(RSA) algorithm (an asymmetric algorithm) to encrypt the key used by the symmetric
cryptography.
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Identity authentication
Digital certificates are used to authenticate a server and a client that need to communicate
with each other. The SSL server and client use the mechanism provided by the public key
infrastructure (PKI) to apply to a CA for a certificate.
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Message integrity
A keyed message authentication code (MAC) is used to verify message integrity during
transmission.
A MAC algorithm computes a key and data of an arbitrary length to generate a MAC of a
fixed length.
Huawei AR1200-S Series Enterprise Routers
Configuration Guide - Security
11 SSL Configuration
Issue 02 (2012-03-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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