---
name: "libressl-X509_VERIFY_PARAM_set_flags"
section: "3"
platform: "linux"
package: "libressl"
version: "4.4.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/libressl-X509_VERIFY_PARAM_set_flags"
---

# libressl-X509\_VERIFY\_PARAM\_set\_flags(3)

X509 verification parameters

## NAME

**X509\_VERIFY\_PARAM\_get0\_name**, **X509\_VERIFY\_PARAM\_set1\_name**, **X509\_VERIFY\_PARAM\_set\_flags**, **X509\_VERIFY\_PARAM\_clear\_flags**, **X509\_VERIFY\_PARAM\_get\_flags**, **X509\_VERIFY\_PARAM\_set\_purpose**, **X509\_VERIFY\_PARAM\_set\_trust**, **X509\_VERIFY\_PARAM\_set\_time**, **X509\_VERIFY\_PARAM\_get\_time**, **X509\_VERIFY\_PARAM\_add0\_policy**, **X509\_VERIFY\_PARAM\_set1\_policies**, **X509\_VERIFY\_PARAM\_set\_depth**, **X509\_VERIFY\_PARAM\_get\_depth**, **X509\_VERIFY\_PARAM\_set\_auth\_level**, **X509\_VERIFY\_PARAM\_set1\_host**, **X509\_VERIFY\_PARAM\_add1\_host**, **X509\_VERIFY\_PARAM\_get\_hostflags**, **X509\_VERIFY\_PARAM\_set\_hostflags**, **X509\_VERIFY\_PARAM\_get0\_peername**, **X509\_VERIFY\_PARAM\_set1\_email**, **X509\_VERIFY\_PARAM\_set1\_ip**, **X509\_VERIFY\_PARAM\_set1\_ip\_asc** – X509 verification parameters

## SYNOPSIS

Crypto Library (libcrypto, -lcrypto)

**#include \<openssl/x509\_vfy.h\>**

*const* *char* *\**\

**X509\_VERIFY\_PARAM\_get0\_name**(*const X509\_VERIFY\_PARAM \*param*);

*int*\

**X509\_VERIFY\_PARAM\_set1\_name**(*X509\_VERIFY\_PARAM \*param*, *const char \*name*);

*int*\

**X509\_VERIFY\_PARAM\_set\_flags**(*X509\_VERIFY\_PARAM \*param*, *unsigned long flags*);

*int*\

**X509\_VERIFY\_PARAM\_clear\_flags**(*X509\_VERIFY\_PARAM \*param*, *unsigned long flags*);

*unsigned* *long*\

**X509\_VERIFY\_PARAM\_get\_flags**(*X509\_VERIFY\_PARAM \*param*);

*int*\

**X509\_VERIFY\_PARAM\_set\_purpose**(*X509\_VERIFY\_PARAM \*param*, *int purpose*);

*int*\

**X509\_VERIFY\_PARAM\_set\_trust**(*X509\_VERIFY\_PARAM \*param*, *int trust*);

*void*\

**X509\_VERIFY\_PARAM\_set\_time**(*X509\_VERIFY\_PARAM \*param*, *time\_t t*);

*time\_t*\

**X509\_VERIFY\_PARAM\_get\_time**(*const*, *X509\_VERIFY\_PARAM*, *\*param"*);

*int*\

**X509\_VERIFY\_PARAM\_add0\_policy**(*X509\_VERIFY\_PARAM \*param*, *ASN1\_OBJECT \*policy*);

*int*\

**X509\_VERIFY\_PARAM\_set1\_policies**(*X509\_VERIFY\_PARAM \*param*, *STACK\_OF(ASN1\_OBJECT) \*policies*);

*void*\

**X509\_VERIFY\_PARAM\_set\_depth**(*X509\_VERIFY\_PARAM \*param*, *int depth*);

*int*\

**X509\_VERIFY\_PARAM\_get\_depth**(*const X509\_VERIFY\_PARAM \*param*);

*void*\

**X509\_VERIFY\_PARAM\_set\_auth\_level**(*X509\_VERIFY\_PARAM \*param*, *int auth\_level*);

*int*\

**X509\_VERIFY\_PARAM\_set1\_host**(*X509\_VERIFY\_PARAM \*param*, *const char \*name*, *size\_t namelen*);

*int*\

**X509\_VERIFY\_PARAM\_add1\_host**(*X509\_VERIFY\_PARAM \*param*, *const char \*name*, *size\_t namelen*);

*unsigned* *int*\

**X509\_VERIFY\_PARAM\_get\_hostflags**(*const X509\_VERIFY\_PARAM \*param*);

*void*\

**X509\_VERIFY\_PARAM\_set\_hostflags**(*X509\_VERIFY\_PARAM \*param*, *unsigned int flags*);

*char* *\**\

**X509\_VERIFY\_PARAM\_get0\_peername**(*X509\_VERIFY\_PARAM \*param*);

*int*\

**X509\_VERIFY\_PARAM\_set1\_email**(*X509\_VERIFY\_PARAM \*param*, *const char \*email*, *size\_t emaillen*);

*int*\

**X509\_VERIFY\_PARAM\_set1\_ip**(*X509\_VERIFY\_PARAM \*param*, *const unsigned char \*ip*, *size\_t iplen*);

*int*\

**X509\_VERIFY\_PARAM\_set1\_ip\_asc**(*X509\_VERIFY\_PARAM \*param*, *const char \*ipasc*);

## DESCRIPTION

These functions manipulate an *X509\_VERIFY\_PARAM* object associated with a certificate verification operation.

**X509\_VERIFY\_PARAM\_get0\_name**() returns the name of the given *param* object, usually describing its purpose, for example "default", "pkcs7", "smime\_sign", "ssl\_client", or "ssl\_server". For user-defined objects, the returned pointer may be NULL even if the object is otherwise valid.

**X509\_VERIFY\_PARAM\_set1\_name**() sets the name of *param* to a copy of *name*, or to NULL if *name* is NULL.

**X509\_VERIFY\_PARAM\_set\_flags**() sets the flags in *param* by OR'ing it with *flags*. See the VERIFICATION FLAGS section for a complete description of values the *flags* parameter can take.

If the *flags* argument includes any of the flags contained in X509\_V\_FLAG\_POLICY\_MASK, that is, any of X509\_V\_FLAG\_POLICY\_CHECK, X509\_V\_FLAG\_EXPLICIT\_POLICY, X509\_V\_FLAG\_INHIBIT\_ANY, and X509\_V\_FLAG\_INHIBIT\_MAP, then X509\_V\_FLAG\_POLICY\_CHECK is set in addition to the flags contained in the *flags* argument.

**X509\_VERIFY\_PARAM\_get\_flags**() returns the flags in *param*.

**X509\_VERIFY\_PARAM\_clear\_flags**() clears the specified *flags* in *param*.

Calling this function can result in unusual internal states of the *param* object, for example having a verification time configured but having X509\_V\_FLAG\_USE\_CHECK\_TIME unset, or having X509\_V\_FLAG\_EXPLICIT\_POLICY set but X509\_V\_FLAG\_POLICY\_CHECK unset, which may have surprising effects.

**X509\_VERIFY\_PARAM\_set\_purpose**() sets the verification *purpose* identifier in *param*. This determines the acceptable purpose of the certificate chain, for example X509\_PURPOSE\_SSL\_CLIENT or X509\_PURPOSE\_SSL\_SERVER. Standard purposes are listed in X509\_check\_purpose(3), and additional purposes can be defined with X509\_PURPOSE\_add(3).

**X509\_VERIFY\_PARAM\_set\_trust**() sets the trust setting in *param* to *trust*.

**X509\_VERIFY\_PARAM\_set\_time**() sets the flag X509\_V\_FLAG\_USE\_CHECK\_TIME in *param* in addition to the flags already set and sets the verification time to *t*. If this function is not called, the current time is used instead, or the UNIX Epoch (January 1, 1970) if X509\_V\_FLAG\_USE\_CHECK\_TIME is manually set using **X509\_VERIFY\_PARAM\_set\_flags**().

**X509\_VERIFY\_PARAM\_add0\_policy**() enables policy checking (it is disabled by default) and adds *policy* to the acceptable policy set.

**X509\_VERIFY\_PARAM\_set1\_policies**() enables policy checking (it is disabled by default) and sets the acceptable policy set to *policies*. Any existing policy set is cleared. The *policies* parameter can be NULL to clear an existing policy set.

**X509\_VERIFY\_PARAM\_set\_depth**() sets the maximum verification depth to *depth*. That is the maximum number of untrusted CA certificates that can appear in a chain.

**X509\_VERIFY\_PARAM\_set\_auth\_level**() sets the security level as defined in SSL\_CTX\_set\_security\_level(3) for certificate chain validation. For a certificate chain to validate, the public keys of all the certificates must meet the specified security level. The signature algorithm security level is not enforced for the chain's trust anchor certificate, which is either directly trusted or validated by means other than its signature.

From the point of view of the X.509 library, the default security level is 0. However, the SSL library uses a different default security level of 1 and calls **X509\_VERIFY\_PARAM\_set\_auth\_level**() with its own level before validating a certificate chain.

**X509\_VERIFY\_PARAM\_set1\_host**() sets the expected DNS hostname to *name* clearing any previously specified hostname or names. If *name* is NULL or empty, the list of hostnames is cleared, and name checks are not performed on the peer certificate. *namelen* should be set to the length of *name*. For historical compatibility, if *name* is NUL-terminated, *namelen* may be specified as zero. When a hostname is specified, certificate verification automatically invokes X509\_check\_host(3) with flags equal to the *flags* argument given to **X509\_VERIFY\_PARAM\_set\_hostflags**() (default zero). **X509\_VERIFY\_PARAM\_set1\_host**() will fail if *name* contains any embedded 0 bytes.

**X509\_VERIFY\_PARAM\_add1\_host**() adds *name* as an additional reference identifier that can match the peer's certificate. Any previous names set via **X509\_VERIFY\_PARAM\_set1\_host**() and **X509\_VERIFY\_PARAM\_add1\_host**() are retained. No change is made if *name* is NULL or empty. *namelen* should be set to the length of *name*. For historical compatibility, if *name* is NUL-terminated, *namelen* may be specified as zero. **X509\_VERIFY\_PARAM\_add1\_host**() will fail if *name* contains any embedded 0 bytes. When multiple names are configured, the peer is considered verified when any name matches.

**X509\_VERIFY\_PARAM\_get0\_peername**() returns the DNS hostname or subject CommonName from the peer certificate that matched one of the reference identifiers. When wildcard matching is not disabled, or when a reference identifier specifies a parent domain (starts with ".") rather than a hostname, the peer name may be a wildcard name or a sub-domain of the reference identifier respectively.

**X509\_VERIFY\_PARAM\_set1\_email**() sets the expected RFC 822 email address to *email*. *emaillen* should be set to the length of *email*. For historical compatibility, if *email* is NUL-terminated, *emaillen* may be specified as zero, **X509\_VERIFY\_PARAM\_set1\_email**() will fail if *email* is NULL, an empty string, or contains embedded 0 bytes. When an email address is specified, certificate verification automatically invokes X509\_check\_email(3).

**X509\_VERIFY\_PARAM\_set1\_ip**() sets the expected IP address to *ip*. The *ip* argument is in binary format, in network byte-order, and *iplen* must be set to 4 for IPv4 and 16 for IPv6. **X509\_VERIFY\_PARAM\_set1\_ip**() will fail if *ip* is NULL or if *iplen* is not 4 or 16. When an IP address is specified, certificate verification automatically invokes X509\_check\_ip(3).

**X509\_VERIFY\_PARAM\_set1\_ip\_asc**() sets the expected IP address to *ipasc*. The *ipasc* argument is a NUL-terminal ASCII string: dotted decimal quad for IPv4 and colon-separated hexadecimal for IPv6. The condensed "::" notation is supported for IPv6 addresses. **X509\_VERIFY\_PARAM\_set1\_ip\_asc**() will fail if *ipasc* is unparsable.

## RETURN VALUES

**X509\_VERIFY\_PARAM\_set1\_name**(), **X509\_VERIFY\_PARAM\_set\_flags**(), **X509\_VERIFY\_PARAM\_clear\_flags**(), **X509\_VERIFY\_PARAM\_set\_purpose**(), **X509\_VERIFY\_PARAM\_set\_trust**(), **X509\_VERIFY\_PARAM\_add0\_policy**(), and **X509\_VERIFY\_PARAM\_set1\_policies**() return 1 for success or 0 for failure.

**X509\_VERIFY\_PARAM\_set1\_host**(), **X509\_VERIFY\_PARAM\_add1\_host**(), **X509\_VERIFY\_PARAM\_set1\_email**(), **X509\_VERIFY\_PARAM\_set1\_ip**(), and **X509\_VERIFY\_PARAM\_set1\_ip\_asc**() return 1 for success or 0 for failure. A failure from these routines will poison the *X509\_VERIFY\_PARAM* object so that future calls to X509\_verify\_cert(3) using the poisoned object will fail.

**X509\_VERIFY\_PARAM\_get\_flags**() returns the current verification flags.

**X509\_VERIFY\_PARAM\_get\_time**() always returns the configured verification time. It does so even if the returned time will not be used because the flag X509\_V\_FLAG\_USE\_CHECK\_TIME is unset.

**X509\_VERIFY\_PARAM\_get\_depth**() returns the current verification depth.

**X509\_VERIFY\_PARAM\_get\_hostflags**() returns the host flags previously set by a call to **X509\_VERIFY\_PARAM\_set\_hostflags**() or 0 by default.

**X509\_VERIFY\_PARAM\_get0\_name**() and **X509\_VERIFY\_PARAM\_get0\_peername**() return pointers to strings that are only valid during the lifetime of the given *param* object and that must not be freed by the application program.

## VERIFICATION FLAGS

The verification flags consists of zero or more of the following flags OR'ed together.

X509\_V\_FLAG\_CRL\_CHECK enables CRL checking for the certificate chain leaf certificate. An error occurs if a suitable CRL cannot be found.

X509\_V\_FLAG\_CRL\_CHECK\_ALL enables CRL checking for the entire certificate chain.

X509\_V\_FLAG\_IGNORE\_CRITICAL disables critical extension checking. By default any unhandled critical extensions in certificates or (if checked) CRLs results in a fatal error. If this flag is set, unhandled critical extensions are ignored. **WARNING**: setting this option for anything other than debugging purposes can be a security risk. Finer control over which extensions are supported can be performed in the verification callback.

The X509\_V\_FLAG\_X509\_STRICT flag disables workarounds for some broken certificates and makes the verification strictly apply X509 rules.

X509\_V\_FLAG\_ALLOW\_PROXY\_CERTS deprecated flag that used to enable proxy certificate verification. In LibreSSL, this flag has no effect.

X509\_V\_FLAG\_POLICY\_CHECK enables certificate policy checking; by default no policy checking is performed. Additional information is sent to the verification callback relating to policy checking.

X509\_V\_FLAG\_EXPLICIT\_POLICY, X509\_V\_FLAG\_INHIBIT\_ANY, and X509\_V\_FLAG\_INHIBIT\_MAP set the “require explicit policy”, “inhibit any policy”, and “inhibit policy mapping” flags, respectively, as defined in RFC 3280. These three flags are ignored unless X509\_V\_FLAG\_POLICY\_CHECK is also set.

If X509\_V\_FLAG\_NOTIFY\_POLICY is set and policy checking is successful, a special status code is sent to the verification callback.

By default some additional features such as indirect CRLs and CRLs signed by different keys are disabled. If X509\_V\_FLAG\_EXTENDED\_CRL\_SUPPORT is set, they are enabled.

If X509\_V\_FLAG\_USE\_DELTAS is set, delta CRLs (if present) are used to determine certificate status. If not set, deltas are ignored.

X509\_V\_FLAG\_CHECK\_SS\_SIGNATURE enables checking of the root CA self signed certificate signature. By default this check is disabled because it doesn't add any additional security but in some cases applications might want to check the signature anyway. A side effect of not checking the root CA signature is that disabled or unsupported message digests on the root CA are not treated as fatal errors.

The deprecated X509\_V\_FLAG\_CB\_ISSUER\_CHECK flag used to enable debugging of certificate issuer checks. It is provided for binary backwards compatibility and has no effect.

When X509\_V\_FLAG\_TRUSTED\_FIRST is set, construction of the certificate chain in X509\_verify\_cert(3) will search the trust store for issuer certificates before searching the provided untrusted certificates. Local issuer certificates are often more likely to satisfy local security requirements and lead to a locally trusted root. This is especially important when some certificates in the trust store have explicit trust settings; see the trust settings options of the **x509** command in [openssl(1)](/openssl/1.md).

The X509\_V\_FLAG\_NO\_ALT\_CHAINS flag suppresses checking for alternative chains. By default, unless X509\_V\_FLAG\_TRUSTED\_FIRST is set, when building a certificate chain, if the first certificate chain found is not trusted, then OpenSSL will attempt to replace untrusted certificates supplied by the peer with certificates from the trust store to see if an alternative chain can be found that is trusted.

The X509\_V\_FLAG\_PARTIAL\_CHAIN flag causes intermediate certificates in the trust store to be treated as trust-anchors, in the same way as the self-signed root CA certificates. This makes it possible to trust certificates issued by an intermediate CA without having to trust its ancestor root CA.

If X509\_V\_FLAG\_USE\_CHECK\_TIME is set, the validity period of certificates and CRLs is checked. In this case, X509\_V\_FLAG\_NO\_CHECK\_TIME is ignored. If the validation time was set with **X509\_VERIFY\_PARAM\_set\_time**(), that time is used. If **X509\_VERIFY\_PARAM\_set\_time**() was not called, the UNIX Epoch (January 1, 1970) is used.

If neither X509\_V\_FLAG\_USE\_CHECK\_TIME nor X509\_V\_FLAG\_NO\_CHECK\_TIME is set, the validity period of certificates and CRLs is checked using the current time. This is the default behaviour. In this case, if a validation time was set with **X509\_VERIFY\_PARAM\_set\_time**() but X509\_V\_FLAG\_USE\_CHECK\_TIME was later cleared with **X509\_VERIFY\_PARAM\_clear\_flags**(), the configured validation time is ignored and the current time is used anyway.

If X509\_V\_FLAG\_USE\_CHECK\_TIME is not set but X509\_V\_FLAG\_NO\_CHECK\_TIME is set, the validity period of certificates and CRLs is not checked at all, and like in the previous case, any configured validation time is ignored.

## EXAMPLES

Enable CRL checking when performing certificate verification during SSL connections associated with an *SSL\_CTX* structure *ctx*:

```
X509_VERIFY_PARAM *param;
param = X509_VERIFY_PARAM_new();
X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK);
SSL_CTX_set1_param(ctx, param);
X509_VERIFY_PARAM_free(param);
```

## SEE ALSO

SSL\_set1\_host(3), SSL\_set1\_param(3), X509\_check\_host(3), X509\_STORE\_CTX\_new(3), X509\_STORE\_new(3), X509\_verify\_cert(3), X509\_VERIFY\_PARAM\_new(3)

## HISTORY

**X509\_VERIFY\_PARAM\_set1\_name**(), **X509\_VERIFY\_PARAM\_set\_flags**(), **X509\_VERIFY\_PARAM\_set\_purpose**(), **X509\_VERIFY\_PARAM\_set\_trust**(), **X509\_VERIFY\_PARAM\_set\_time**(), **X509\_VERIFY\_PARAM\_add0\_policy**(), **X509\_VERIFY\_PARAM\_set1\_policies**(), **X509\_VERIFY\_PARAM\_set\_depth**(), and **X509\_VERIFY\_PARAM\_get\_depth**() first appeared in OpenSSL 0.9.8. **X509\_VERIFY\_PARAM\_clear\_flags**() and **X509\_VERIFY\_PARAM\_get\_flags**() first appeared in OpenSSL 0.9.8a. All these functions have been available since OpenBSD 4.5.

**X509\_VERIFY\_PARAM\_get0\_name**(), **X509\_VERIFY\_PARAM\_set1\_host**(), **X509\_VERIFY\_PARAM\_add1\_host**(), **X509\_VERIFY\_PARAM\_set\_hostflags**(), **X509\_VERIFY\_PARAM\_get0\_peername**(), **X509\_VERIFY\_PARAM\_set1\_email**(), **X509\_VERIFY\_PARAM\_set1\_ip**(), and **X509\_VERIFY\_PARAM\_set1\_ip\_asc**() first appeared in OpenSSL 1.0.2 and have been available since OpenBSD 6.3.

**X509\_VERIFY\_PARAM\_set\_auth\_level**() first appeared in OpenSSL 1.1.0 and **X509\_VERIFY\_PARAM\_get\_time**() in OpenSSL 1.1.0d. Both functions have been available since OpenBSD 7.2.

**X509\_VERIFY\_PARAM\_get\_hostflags**() first appeared in OpenSSL 1.1.0i and has been available since OpenBSD 7.9.

## BUGS

Delta CRL checking is currently primitive. Only a single delta can be used and (partly due to limitations of *X509\_STORE*) constructed CRLs are not maintained.

If CRLs checking is enabled, CRLs are expected to be available in the corresponding *X509\_STORE* structure. No attempt is made to download CRLs from the CRL distribution points extension.