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CURLOPT_ISSUERCERT(3) curl_easy_setopt options CURLOPT_ISSUERCERT(3)
CURLOPT_ISSUERCERT - issuer SSL certificate filename
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ISSUERCERT, char *file);
Pass a char * to a null-terminated string naming a file holding a CA
certificate in PEM format. If the option is set, an additional check
against the peer certificate is performed to verify the issuer is
indeed the one associated with the certificate provided by the option.
This additional check is useful in multi-level PKI where one needs to
enforce that the peer certificate is from a specific branch of the
This option makes sense only when used in combination with the
CURLOPT_SSL_VERIFYPEER(3) option. Otherwise, the result of the check is
not considered as failure.
A specific error code (CURLE_SSL_ISSUER_ERROR) is defined with the
option, which is returned if the setup of the SSL/TLS session has
failed due to a mismatch with the issuer of peer certificate
(CURLOPT_SSL_VERIFYPEER(3) has to be set too for the check to fail).
(Added in 7.19.0)
The application does not have to keep the string around after setting
All TLS-based protocols
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
curl_easy_setopt(curl, CURLOPT_ISSUERCERT, "/etc/certs/cacert.pem");
ret = curl_easy_perform(curl);
If built TLS enabled
Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if
not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space.
libcurl 7.83.1 November 26, 2021 CURLOPT_ISSUERCERT(3)