Based on a patch brought by Johnny Luong, libcurl now offers

Based on a patch brought by Johnny Luong, libcurl now offers
CURLOPT_SSH_HOST_PUBLIC_KEY_MD5 and the curl tool --hostpubmd5. They both make
the SCP or SFTP connection verify the remote host's md5 checksum of the public
key before doing a connect, to reduce the risk of a man-in-the-middle attack.