gnutls_certificate_verify_peers — API function


#include <gnutls/gnutls.h>

int gnutls_certificate_verify_peers(gnutls_session_t session, gnutls_typed_vdata_st * data, unsigned int elements, unsigned int * status);


gnutls_session_t session

is a gnutls session

gnutls_typed_vdata_st * data

an array of typed data

unsigned int elements

the number of data elements

unsigned int * status

is the output of the verification


This function will verify the peer's certificate and store the the status in the  status variable as a bitwise OR of gnutls_certificate_status_t values or zero if the certificate is trusted. Note that value in  status is set only when the return value of this function is success (i.e, failure  to trust a certificate does not imply a negative return value). The default verification flags used by this function can be overridden using gnutls_certificate_set_verify_flags(). See the documentation of gnutls_certificate_verify_peers2() for details in the verification process.

This function will take into account the stapled OCSP responses sent by the server, as well as the following X.509 certificate extensions: Name Constraints, Key Usage, and Basic Constraints (pathlen).

The acceptable  data types are GNUTLS_DT_DNS_HOSTNAME, GNUTLS_DT_RFC822NAME and GNUTLS_DT_KEY_PURPOSE_OID. The former two accept as data a null-terminated hostname or email address, and the latter a null-terminated object identifier (e.g., GNUTLS_KP_TLS_WWW_SERVER).

If a DNS hostname is provided then this function will compare the hostname in the certificate against the given. If names do not match the  GNUTLS_CERT_UNEXPECTED_OWNER status flag will be set. If a key purpose OID is provided and the end-certificate contains the extended key usage PKIX extension, it will be required to be have the provided key purpose  or be marked for any purpose, otherwise verification status will have the GNUTLS_CERT_SIGNER_CONSTRAINTS_FAILURE flag set.

To avoid denial of service attacks some default upper limits regarding the certificate key size and chain size are set. To override them use gnutls_certificate_set_verify_limits().

Note that when using raw public-keys verification will not work because there is no corresponding certificate body belonging to the raw key that can be verified. In that case this function will return GNUTLS_E_INVALID_REQUEST.


GNUTLS_E_SUCCESS (0) when the validation is performed, or a negative error code otherwise. A successful error code means that the  status parameter must be checked to obtain the validation status.



Reporting Bugs

Report bugs to <>.
Home page:

See Also

The full documentation for gnutls is maintained as a Texinfo manual. If the /usr/share/doc/gnutls/ directory does not contain the HTML form visit


3.6.9 gnutls