Computer Science – 17.1 Encryption, Encryption Protocols and Digital Certificates | e-Consult
17.1 Encryption, Encryption Protocols and Digital Certificates (1 questions)
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A Certificate Authority (CA) plays a crucial role in establishing trust in SSL/TLS communication. Its primary roles are:
- Certificate Issuance: The CA issues digital certificates to entities (e.g., websites, servers). These certificates contain the entity's public key, identity information, and the CA's digital signature.
- Certificate Validation: When a client receives a server's certificate, it must validate the certificate's authenticity. This involves checking:
- Signature Verification: The client uses the CA's public key (which is pre-installed in the client's trust store) to verify the CA's digital signature on the certificate. This confirms that the certificate was issued by a trusted CA.
- Certificate Revocation List (CRL) / Online Certificate Status Protocol (OCSP): The client checks if the certificate has been revoked by the CA. Revocation might occur if the private key associated with the certificate has been compromised.
- Chain of Trust: The certificate may be part of a chain of certificates, where each certificate is signed by a higher-level CA. The client verifies the entire chain to ensure the certificate ultimately originates from a trusted root CA.
- Maintaining Trust: CAs are trusted entities. Their root certificates are pre-installed in operating systems and web browsers. This establishes a baseline level of trust.
Importance of Trust: Trust is paramount in SSL/TLS. Without trust in the CA, clients would not be able to verify the identity of the server and would be vulnerable to man-in-the-middle attacks. A man-in-the-middle attack occurs when an attacker intercepts the communication between the client and the server, impersonating both parties. This allows the attacker to eavesdrop on the communication or even modify it.