CURLOPT_SSH_PUBLIC_KEYFILE - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_PUBLIC_KEYFILE,
                          char *filename);

Pass a char pointer pointing to a filename for your public key. If not used, libcurl defaults to $HOME/.ssh/id_dsa.pub if the HOME environment variable is set, and just "id_dsa.pub" in the current directory if HOME is not set.

If NULL (or an empty string) is passed to this option, libcurl passes no public key to the SSH library, which then rather derives it from the private key. If the SSH library cannot derive the public key from the private one and no public one is provided, the transfer fails.

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

NULL

This functionality affects scp and sftp

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "sftp://example.com/file");
    curl_easy_setopt(curl, CURLOPT_SSH_PUBLIC_KEYFILE,
                     "/home/clarkkent/.ssh/id_rsa.pub");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

The "" trick was added in 7.26.0

Added in curl 7.16.1

Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space.

CURLOPT_SSH_AUTH_TYPES(3), CURLOPT_SSH_PRIVATE_KEYFILE(3)

curl_easy_setopt(3), CURLOPT_SSH_AUTH_TYPES(3), CURLOPT_SSH_HOST_PUBLIC_KEY_MD5(3), CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256(3), CURLOPT_SSH_PRIVATE_KEYFILE(3), libcurl-symbols(3).