---
name: "X509V3_set_ctx"
section: "3ssl"
platform: "linux"
package: "openssl"
version: "3.6.5-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/X509V3_set_ctx"
---

# X509V3\_set\_ctx(3ssl)

X.509 v3 extension generation utilities

## NAME

X509V3\_set\_ctx, X509V3\_set\_issuer\_pkey - X.509 v3 extension generation utilities

## 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);
```

## DESCRIPTION

**X509V3\_set\_ctx()** fills in the basic fields of *ctx* of type **X509V3\_CTX**, providing details potentially needed by functions producing X509 v3 extensions. These may make use of fields of the certificate *subject*, the certification request *req*, or the certificate revocation list *crl*. At most one of these three parameters can be non-NULL. 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 an 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()**. *flags* may be 0 or contain **X509V3\_CTX\_TEST**, which means that just the syntax of extension definitions is to be checked without actually producing any extension, or **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.

**X509V3\_set\_issuer\_pkey()** explicitly sets the issuer private key of the subject certificate that has been provided in *ctx*. This should be done in case the *issuer* and *subject* arguments to **X509V3\_set\_ctx()** have the same pointer value to provide fallback data for the authority key identifier extension.

## RETURN VALUES

**X509V3\_set\_issuer\_pkey()** returns 1 on success and 0 on error.

## SEE ALSO

**X509\_add\_ext**(3)

## HISTORY

**X509V3\_set\_issuer\_pkey()** was added in OpenSSL 3.0.

CTX\_TEST was deprecated in OpenSSL 3.0; use X509V3\_CTX\_TEST instead.

## 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\>.