X509_CHECK_ISSUED(3)

📦 version 4.4.0, in alpine 3.24, arch rolling

🌸 NAME 🌸

okay so welcome to the X509_CHECK_ISSUED(3) page from the Library Functions Manual, bestie 💖 we’re talking about X509_check_issued — check whether a certificate was issued using a given CA certificate. periodt.

✨ SYNOPSIS ✨

here’s the exact synopsis, no cap:

library “libcrypto” #include <openssl/x509v3.h>

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

🦋 DESCRIPTION 🦋

so X509_check_issued checks whether the certificate subject was issued using the CA certificate issuer. it does these checks, bestie:

  • match the issuer field of subject against the subject field of issuer — it’s giving “do these match?” energy 👀
  • if authorityKeyIdentifier is present in the subject certificate, compare it to the subjectKeyIdentifier of issuer
  • check the keyUsage field of issuer

that’s the whole vibe check 🔥.

💖 RETURN VALUES 💖

this function returns X509_V_OK if the certificate subject is issued by issuer — slay — or some X509_V_ERR* constant to indicate an error. so yeah, X509_V_OK is the good ending, and the X509_V_ERR* constants are the “something went sideways” endings 😭.

🌈 SEE ALSO 🌈

go read these too, iykyk 🫶.

🎀 HISTORY 🎀

X509_check_issued() first appeared in OpenSSL 0.9.6 and has been available since OpenBSD 2.9. iconic history fr fr 👑.

okay that’s the whole page, bestie — this one comes from Debian and is dated June 8, 2025. mwah 💋✨

📦 where this page comes from