Security
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What is Certificate Pinning?
A security technique that associates a host with its expected TLS certificate or public key, preventing man-in-the-middle attacks with fraudulent certificates.
Certificate pinning validates that a server presents a specific certificate or public key, rather than any certificate signed by a trusted CA. This protects against compromised Certificate Authorities and rogue certificates. Implementation approaches include pinning the leaf certificate (most restrictive), pinning the intermediate CA certificate, or pinning the public key (most flexible during certificate renewal). Mobile apps commonly use certificate pinning for API communication. Challenges include handling certificate rotation (pin the backup key too) and debugging (pinning failures are silent). HTTP Public Key Pinning (HPKP) for browsers was deprecated due to the risk of permanent lockout.
