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CURLOPT_ISSUERCERT(3)	    Library Functions Manual	   CURLOPT_ISSUERCERT(3)

NAME
     CURLOPT_ISSUERCERT - issuer SSL certificate filename

SYNOPSIS
     #include <curl/curl.h>

     CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ISSUERCERT, char *file);

DESCRIPTION
     Pass  a char pointer 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  addi-
     tional  check  is useful in multi-level PKI where one needs to enforce that
     the peer certificate is from a specific branch of the tree.

     This option makes sense  only  when  used	in  combination  with  the  CUR-
     LOPT_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).

     Using this option multiple times makes the last  set  string  override  the
     previous ones. Set it to NULL to disable its use again.

     The  application does not have to keep the string around after setting this
     option.

DEFAULT
     NULL

PROTOCOLS
     This functionality affects all TLS based  protocols:  HTTPS,  FTPS,  IMAPS,
     POP3S, SMTPS etc.

     This option works only with the following TLS backends: GnuTLS and OpenSSL

EXAMPLE
     int main(void)
     {
       CURL *curl = curl_easy_init();
       if(curl) {
	 CURLcode result;
	 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
	 curl_easy_setopt(curl, CURLOPT_ISSUERCERT, "/etc/certs/cacert.pem");
	 result = curl_easy_perform(curl);
	 curl_easy_cleanup(curl);
       }
     }

AVAILABILITY
     Added in curl 7.19.0

RETURN VALUE
     curl_easy_setopt(3) returns a CURLcode indicating success or error.

     CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
     libcurl-errors(3).

SEE ALSO
     CURLOPT_CRLFILE(3), CURLOPT_SSL_VERIFYHOST(3), CURLOPT_SSL_VERIFYPEER(3)

libcurl 			   2026-06-11		   CURLOPT_ISSUERCERT(3)

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