---
name: "SSL_CTX_get0_param"
section: "3ssl"
platform: "linux"
package: "openssl"
version: "3.6.5-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/SSL_CTX_get0_param"
---

# SSL\_CTX\_get0\_param(3ssl)

get and set verification parameters

## NAME

SSL\_CTX\_get0\_param, SSL\_get0\_param, SSL\_CTX\_set1\_param, SSL\_set1\_param, SSL\_CTX\_set\_purpose, SSL\_CTX\_set\_trust, SSL\_set\_purpose, SSL\_set\_trust - get and set verification parameters

## SYNOPSIS

```
 #include <openssl/ssl.h>
 X509_VERIFY_PARAM *SSL_CTX_get0_param(SSL_CTX *ctx);
 X509_VERIFY_PARAM *SSL_get0_param(SSL *ssl);
 int SSL_CTX_set1_param(SSL_CTX *ctx, X509_VERIFY_PARAM *vpm);
 int SSL_set1_param(SSL *ssl, X509_VERIFY_PARAM *vpm);
 int SSL_CTX_set_purpose(SSL_CTX *ctx, int purpose);
 int SSL_set_purpose(SSL *ssl, int purpose);
 int SSL_CTX_set_trust(SSL_CTX *ctx, int trust);
 int SSL_set_trust(SSL *ssl, int trust);
```

## DESCRIPTION

**SSL\_CTX\_get0\_param()** and **SSL\_get0\_param()** retrieve an internal pointer to the verification parameters for **ctx** or **ssl** respectively. The returned pointer must not be freed by the calling application.

**SSL\_CTX\_set1\_param()** and **SSL\_set1\_param()** set the verification parameters to **vpm** for **ctx** or **ssl**.

The functions **SSL\_CTX\_set\_purpose()** and **SSL\_set\_purpose()** are shorthands which set the purpose parameter on the verification parameters object. These functions are equivalent to calling **X509\_VERIFY\_PARAM\_set\_purpose()** directly.

The functions **SSL\_CTX\_set\_trust()** and **SSL\_set\_trust()** are similarly shorthands which set the trust parameter on the verification parameters object. These functions are equivalent to calling **X509\_VERIFY\_PARAM\_set\_trust()** directly.

## NOTES

Typically parameters are retrieved from an **SSL\_CTX** or **SSL** structure using **SSL\_CTX\_get0\_param()** or **SSL\_get0\_param()** and an application modifies them to suit its needs: for example to add a hostname check.

## RETURN VALUES

**SSL\_CTX\_get0\_param()** and **SSL\_get0\_param()** return a pointer to an **X509\_VERIFY\_PARAM** structure.

**SSL\_CTX\_set1\_param()**, **SSL\_set1\_param()**, **SSL\_CTX\_set\_purpose()**, **SSL\_set\_purpose()**, **SSL\_CTX\_set\_trust()** and **SSL\_set\_trust()** return 1 for success and 0 for failure.

## EXAMPLES

Check hostname matches "www.foo.com" in peer certificate:

```
 X509_VERIFY_PARAM *vpm = SSL_get0_param(ssl);
 X509_VERIFY_PARAM_set1_host(vpm, "www.foo.com", 0);
```

## SEE ALSO

[**ssl**(7)](/ssl/7.md), **X509\_VERIFY\_PARAM\_set\_flags**(3)

## HISTORY

These functions were added in OpenSSL 1.0.2.

## COPYRIGHT

Copyright 2015-2022 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\>.