X509_CHECK_ISSUED(3ossl)

📦
version 3.5.9 · 8 versions
, in fedora 43, fedora 44

💅 X509_CHECK_ISSUED — the OpenSSL glow-up 🎀

okay bestie, so this one's from the OpenSSL manual, section 3ossl — and it's literally the girl who checks if one certificate was issued by another. yes, she does the vibe check so you don't have to. ✨

🦋 NAME 🦋

X509_check_issued — checks if certificate is apparently issued by another certificate

🌸 SYNOPSIS 🌸

#include <openssl/x509v3.h>

int X509_check_issued(X509 *issuer, X509 *subject);

💖 DESCRIPTION 💖

okay so X509_check_issued() is the function that checks if the certificate subject was apparently issued using the (CA) certificate issuer. she's the main character of parentage checks, fr fr. 🫶

and the way she does it is not just a lazy little string compare, no ma'am. she takes into account not only matching of the issuer field of subject with the subject field of issuer, but also compares all sub-fields of the authorityKeyIdentifier extension of subject, as far as present, with the respective subjectKeyIdentifier, serial number, and issuer fields of issuer, as far as present. she's thorough like that. 💅

she also checks if the keyUsage field (if present) of issuer allows certificate signing. iconic behavior honestly.

🚨 but ngl, plot twist: she does not actually check the certificate signature. that part is not her job, bestie. don't ask her to do everything.

and an error is returned if the issuer or the subject are incomplete certificates. incomplete?? she's not doing it. 💀

⭐ RETURN VALUES ⭐

  • X509_check_issued() returns X509_V_OK if all checks are successful
  • ...or some X509_V_ERR* constant to indicate an error 😭

🎀 SEE ALSO 🎀

Copyright 2015-2021 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 that's the whole page bestie, no cap. 💜 this was OpenSSL version 3.5.9, dated 2026-09-29 — mwah, slay, periodt. 🌈✨

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