NAME

       CURLOPT_PROXY_ISSUERCERT_BLOB - proxy issuer SSL certificate from memory blob

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_ISSUERCERT_BLOB,
                                 struct curl_blob *blob);

DESCRIPTION

       Pass  a pointer to a curl_blob struct, which contains information (pointer and size) about a memory block
       with binary data of a CA certificate in PEM format. If the option is set, an additional check against the
       peer certificate is performed to verify the issuer of the HTTPS proxy 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 tree.

       This option should be used in combination with the CURLOPT_PROXY_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_PROXY_SSL_VERIFYPEER(3) has to be set too for the check to fail).

       If  the  blob  is  initialized  with  the  flags  member  of  struct curl_blob set to CURL_BLOB_COPY, the
       application does not have to keep the buffer around after setting this.

       This option is an alternative to CURLOPT_PROXY_ISSUERCERT(3) which instead expects a filename as input.

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: OpenSSL

EXAMPLE

       extern char *certificateData; /* point to the data */
       size_t filesize; /* size of the data */

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           CURLcode res;
           struct curl_blob blob;
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
           /* using an HTTPS proxy */
           curl_easy_setopt(curl, CURLOPT_PROXY, "https://localhost:443");
           blob.data = certificateData;
           blob.len = filesize;
           blob.flags = CURL_BLOB_COPY;
           curl_easy_setopt(curl, CURLOPT_PROXY_ISSUERCERT_BLOB, &blob);
           res = curl_easy_perform(curl);
           curl_easy_cleanup(curl);
         }
       }

AVAILABILITY

       Added in curl 7.71.0

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_ISSUERCERT_BLOB(3),       CURLOPT_PROXY_SSL_VERIFYHOST(3),       CURLOPT_PROXY_SSL_VERIFYPEER(3),
       CURLOPT_SSL_VERIFYHOST(3), CURLOPT_SSL_VERIFYPEER(3)

libcurl                                            2025-06-16                   CURLOPT_PROXY_ISSUERCERT_BLOB(3)