X509V3_SET_CTX(3ossl)

💅 X509V3_set_ctx — the OpenSSL 3ossl era ✨

okay bestie, welcome to the X.509 v3 extension generation utilities page — aka the little setup functions that make your cert extensions actually know what's going on 🎀

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✨ SYNOPSIS ✨

#include <openssl/x509v3.h>

void X509V3_set_ctx(X509V3_CTX *ctx, X509 *issuer, X509 *subject,
                    X509_REQ *req, X509_CRL *crl, int flags);
int X509V3_set_issuer_pkey(X509V3_CTX *ctx, EVP_PKEY *pkey);

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🌸 DESCRIPTION 🌸

So X509V3_set_ctx() basically fills in the basic fields of ctx (which is of type X509V3_CTX) — it's handing over the details that functions producing X509 v3 extensions might lowkey need later 🫶 Those functions may end up making use of fields of the certificate subject, the certification request req, or the certificate revocation list crl.

🚨 Important vibe check: at most one of these three parameters (subject, req, crl) can be non-NULL. Pick one, bestie, not all three 😭

Here's the tea on how the fallbacks work:

• When constructing the subject key identifier of a certificate by computing a hash value of its public key, the public key is taken from subject or req.
• Similarly, when constructing subject alternative names from any email addresses contained in a subject DN, the subject DN is taken from subject or req.
• If subject or crl is provided, issuer should point to its issuer — for instance as a reference for generating the authority key identifier extension.
• issuer may be the same pointer value as subject (which usually is a lil' indication that the subject certificate is self-issued or even self-signed 👑). In this case the fallback source for generating the authority key identifier extension will be taken from any value provided using X509V3_set_issuer_pkey().

Now for flags — it can be 0, or it can contain:

• X509V3_CTX_TEST — which means that just the syntax of extension definitions is to be checked, without actually producing any extension. It's giving "vibe check only, no actual build" 💀
• X509V3_CTX_REPLACE — which means that each X.509v3 extension added as defined in some configuration section shall replace any already existing extension with the same OID. Out with the old, in with the new, periodt 🔥

Then there's X509V3_set_issuer_pkey() — it explicitly sets the issuer private key of the subject certificate that has been provided in ctx. You should do this in case the issuer and subject arguments to X509V3_set_ctx() have the same pointer value, so you've got fallback data for the authority key identifier extension 🦋

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💖 RETURN VALUES 💖

X509V3_set_issuer_pkey() returns 1 on success and 0 on error. That's it, that's the whole return value section, slay ✨

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🦋 SEE ALSO 🦋

• X509_add_ext(3)

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🎀 HISTORY 🎀

• X509V3_set_issuer_pkey() was added in OpenSSL 3.0.
• CTX_TEST was deprecated in OpenSSL 3.0; use X509V3_CTX_TEST instead. Yeah girl, the old name is giving expired, use the new one 🙈

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👑 COPYRIGHT 👑

Copyright 2015-2025 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>.

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okay that's the whole page, no cap 💜 this was 3.5.6, dated 2026-04-07, and it's the X509V3_SET_CTX(3ossl) manual — go forth and set your ctx, bestie, you're gonna ate 🌈⭐