cert-parse

What this skill does

Accepts an X.509 certificate file or PEM text and uses openssl x509 to parse the Subject, Issuer, SAN, validity period, public key info, and extension fields. If a CA bundle is provided, performs chain verification with openssl verify, and automatically checks for common issues such as weak keys, expiry, and self-signing.

When to use

• Inspecting a server certificate before or after deployment
• Debugging certificate chain errors (e.g., UNABLE_TO_GET_ISSUER_CERT)
• Checking certificate-related vulnerabilities (weak keys, wildcard misuse, etc.) during bug bounty or penetration testing

Prerequisites

• openssl installed (built into Linux/macOS)
• Certificate file (PEM/DER) or PEM text
• CA bundle file for chain verification (optional)

Inputs