X509_CHECK_ISSUED(3) | Library Functions Manual | X509_CHECK_ISSUED(3)

# NAME

`X509_check_issued` — check whether a certificate was issued using a given CA certificate

# SYNOPSIS

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

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

# DESCRIPTION

This function checks whether the certificate subject was issued using the CA certificate issuer. It does the following checks:

- match the issuer field of subject against the subject field of issuer
- if authorityKeyIdentifier is present in the subject certificate, compare it to the subjectKeyIdentifier of issuer
- check the keyUsage field of issuer.

# RETURN VALUES

This function returns `X509_V_OK` if the certificate subject is issued by issuer, or some `X509_V_ERR*` constant to indicate an error.

# SEE ALSO

X509_check_ca(3), X509_new(3), X509_verify_cert(3)

# HISTORY

`X509_check_issued`() first appeared in OpenSSL 0.9.6 and has been available since OpenBSD 2.9.

June 8, 2025 | Debian