X509(7SSL)

📦
version 4.0.3 · 13 versions
, in ubuntu stonking

💖 X509(7SSL) — the OpenSSL glow-up guide to X.509 certificate handling 💖

ok bestie, so this is X509(7SSL), one of the OpenSSL manual pages, and we're about to make certificate handling make sense. buckle up, it's giving "cryptography but cute". 🎀

✨ SYNOPSIS ✨

#include <openssl/x509.h>

that's it. that's the whole vibe. one include and you're in. 💅

🌸 DESCRIPTION 🌸

okay so picture this: an X.509 certificate is literally just a structured grouping of information about an individual, a device, or honestly anything you can imagine. no cap — anything. 🦋

and an X.509 CRL (aka a certificate revocation list) is the tool that helps you figure out if a certificate is still valid or if it's been ghosted. 💀

where do the exact definitions live? in the X.509 document from ITU-T, or in RFC3280 from PKIX. if you want the receipts, that's where they're at. 📚

in OpenSSL specifically:

  • the type X509 is how we express a certificate
  • the type X509_CRL is how we express a CRL

a related structure is a certificate request, which is defined in PKCS#10 from RSA Security, Inc — and it's also reflected in RFC2896. in OpenSSL, the type X509_REQ is how we express one of those. 🫶

now, to handle some of the complex parts of a certificate, there are a few more types, and they are iconic:

  • X509_NAME — to express a certificate name
  • X509_ATTRIBUTE — to express a certificate attribute
  • X509_EXTENSION — to express a certificate extension
  • and a few more beyond that 👑

and finally — final boss energy — there's the supertype X509_INFO, which can contain a CRL, a certificate, and a corresponding private key. all three. together. main character behavior. ✨

🧚 the function families (iykyk)

here's who handles what, fr fr:

  • X509_XXX, d2i_X509_XXX, and i2d_X509_XXX functions handle X.509 certificates — with some exceptions, shown below. 🚨
  • X509_CRL_XXX, d2i_X509_CRL_XXX, and i2d_X509_CRL_XXX functions handle X.509 CRLs.
  • X509_REQ_XXX, d2i_X509_REQ_XXX, and i2d_X509_REQ_XXX functions handle PKCS#10 certificate requests.
  • X509_NAME_XXX functions handle certificate names.
  • X509_ATTRIBUTE_XXX functions handle certificate attributes.
  • X509_EXTENSION_XXX functions handle certificate extensions.

see how it all clicks? every type has its lil squad of functions. obsessed. 💖

🔥 SEE ALSO 🔥

go read these next, bestie, they're all connected:

Copyright 2003-2021 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

okay real talk for a sec: that license stuff matters, don't skip it. read the License, comply with the License, be a good citizen. 💜

and that's the whole page, bestie!! 🌈 this was OpenSSL version 4.0.3, dated 2026-09-29, and it's the X509(7SSL) manual page. mwah. slay, stay certified, and go read your certs. 🍓💅✨

📦 where this page comes from