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X.509 Certificate Decoder

Decode and analyze X.509 SSL/TLS certificates. Parse PEM, DER, and CRT formats with detailed certificate chain validation and security analysis.

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References & Citations

  1. D. Cooper et al.. (2008). RFC 5280: Internet X.509 Public Key Infrastructure Certificate and CRL Profile. Internet Engineering Task Force. Retrieved from https://www.rfc-editor.org/rfc/rfc5280 (accessed January 2025)
  2. International Telecommunication Union. (2019). ITU-T X.509 Recommendation. Retrieved from https://www.itu.int/rec/T-REC-X.509/ (accessed January 2025)
  3. B. Laurie et al.. (2013). Certificate Transparency (RFC 6962). Internet Engineering Task Force. Retrieved from https://www.rfc-editor.org/rfc/rfc6962 (accessed January 2025)
  4. CA/Browser Forum. (2024). CA/Browser Forum Baseline Requirements. Retrieved from https://cabforum.org/baseline-requirements-documents/ (accessed January 2025)

Note: These citations are provided for informational and educational purposes. Always verify information with the original sources and consult with qualified professionals for specific advice related to your situation.

Key Security Terms

Understand the essential concepts behind this tool

X.509 Certificate

A digital certificate standard that binds a public key to an identity, enabling encrypted connections and authentication.

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Certificate Transparency (CT)

A public logging system that records all SSL/TLS certificates, enabling detection of misissued or malicious certificates.

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Subresource Integrity (SRI)

A security feature that allows browsers to verify that files from CDNs have not been tampered with.

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File Signatures (Magic Numbers)

Unique byte sequences at the start of files that identify the file type, regardless of extension.

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View all terms in our glossary →

⚠️ Security Notice

This tool is provided for educational and authorized security testing purposes only. Always ensure you have proper authorization before testing any systems or networks you do not own. Unauthorized access or security testing may be illegal in your jurisdiction. All processing happens client-side in your browser - no data is sent to our servers.