DeepSeek, like other clients, verifies the Common Name (CN) in an SSL certificate as part of the SSL/TLS handshake process. Here's a detailed explanation of how this verification typically occurs:
1. Certificate Receipt: When a client (like DeepSeek) initiates a connection to a server, the server responds by sending its SSL/TLS certificate. This certificate contains various fields, including the Common Name (CN) and the Subject Alternative Name (SAN).
2. Certificate Validation: The client checks the certificate to ensure it is valid and has not expired. It verifies the digital signature of the certificate using the public key of the Certificate Authority (CA) that issued it. The client also checks if the certificate has been revoked by consulting a Certificate Revocation List (CRL) or using the Online Certificate Status Protocol (OCSP) responder[4].
3. Common Name Verification: The client checks if the domain name in the certificate matches the domain name of the website being accessed. This is crucial to ensure that the certificate is issued for the correct domain. If the domain names do not match, the client will typically display a warning message to the user[1][4].
4. SAN Verification: Although the Common Name field is often considered legacy, modern verification processes rely more on the SAN field. The SAN allows for multiple domain names to be specified, including wildcard domains. The client checks both the CN and SAN fields to ensure that the server's domain name is listed[1][3].
5. Trust Store Verification: The client verifies that the CA issuing the certificate is trusted by checking if it is included in its trust store. If the CA is not trusted, the certificate is considered untrusted[4].
6. Encryption Negotiation: If all verification steps pass, the client proceeds to negotiate an encryption algorithm with the server and establishes a secure connection using protocols like Transport Layer Security (TLS)[4].
In the context of DeepSeek or similar applications, these steps ensure that the connection to the server is secure and that the server is who it claims to be, preventing potential man-in-the-middle attacks. However, specific implementation details might vary depending on how DeepSeek is configured to handle SSL/TLS connections.
Citations:
[1] https://support.dnsimple.com/articles/what-is-common-name/
[2] https://www.certauri.com/understanding-ssl-certificate-common-name-secure-your-site/
[3] https://opensearch.org/docs/latest/troubleshoot/tls/
[4] https://apidog.com/blog/ssl-certificate-verification/
[5] https://www.ssl.com/faqs/common-name/
[6] https://opensearch.org/docs/latest/security/configuration/tls/
[7] https://www.digitalocean.com/community/questions/how-to-get-the-ssl-certificate-details-for-a-specific-domain-via-the-command-line
[8] https://stackoverflow.com/questions/35374491/how-does-the-client-verify-servers-certificate-in-ssl