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CURLOPT_PROXY_SSLKEY_BLOB - private key for proxy cert from memory blob

#include <curl/curl.h>

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

Pass a pointer to a curl_blob structure that contains information (pointer and size) about the private key for connecting to the HTTPS proxy. Compatible with OpenSSL. The format (like "PEM") must be specified with CURLOPT_PROXY_SSLKEYTYPE(3). 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. NULL All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

CURL *curl = curl_easy_init();
if(curl) {
 struct curl_blob blob;
 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
 curl_easy_setopt(curl, CURLOPT_PROXY, "https://proxy");
 blob.data = certificateData;
 blob.len = filesize;
 blob.flags = CURL_BLOB_COPY;
 curl_easy_setopt(curl, CURLOPT_PROXY_SSLCERT_BLOB, &blob);
 curl_easy_setopt(curl, CURLOPT_PROXY_SSLCERTTYPE, "PEM");

 blob.data = privateKeyData;
 blob.len = privateKeySize;
 curl_easy_setopt(curl, CURLOPT_PROXY_SSLKEY_BLOB, &blob);
 curl_easy_setopt(curl, CURLOPT_PROXY_KEYPASSWD, "s3cret");
 ret = curl_easy_perform(curl);
 curl_easy_cleanup(curl);
}

Added in libcurl 7.71.0. This option is supported by the OpenSSL backends. Returns CURLE_OK if TLS enabled, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space. CURLOPT_SSLKEYTYPE "(3), " CURLOPT_SSLKEY "(3), "