CURLOPT_SSLENGINE - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLENGINE, char *id);

Pass a pointer to a null-terminated string as parameter. It is used as the identifier for the crypto engine you want to use for your private key.

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

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

NULL

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

This option works only with the following TLS backends: OpenSSL

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_SSLENGINE, "dynamic");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Added in curl 7.9.3

CURLE_OK - Engine found.

CURLE_SSL_ENGINE_NOTFOUND - Engine not found, or OpenSSL was not built with engine support.

CURLE_SSL_ENGINE_INITFAILED - Engine found but initialization failed.

CURLE_NOT_BUILT_IN - Option not built in, OpenSSL is not the SSL backend.

CURLE_UNKNOWN_OPTION - Option not recognized.

CURLE_OUT_OF_MEMORY - Insufficient heap space.

CURLINFO_SSL_ENGINES(3), CURLOPT_SSLENGINE_DEFAULT(3), CURLOPT_SSLKEY(3)

curl_easy_setopt(3), CURLINFO_SSL_ENGINES(3), CURLOPT_SSLENGINE_DEFAULT(3), CURLOPT_SSLKEYTYPE(3), libcurl-symbols(3).