How to use EXPECT in a loop for ssh

Our Linux setup doesn't have keygen configured for passwordless authentication. Hence I am supposed to use only EXPECT for passwordless authentication in a shell script. /usr/bin/expect> ${LOG_FILE} set timeout 60 spawn sftp ${EWS_USER}@${EWS_HOST}:${TGT_DIR} expect "*?assword:" send "$password\r" expect "sftp>" send "put $local_dir/$line\r" expect "sftp>" send "bye\r" expect EOF EOF filename=$(basename "$line") # echo "File Name: $filename" #Calculate the MD5Sum locally. local_md5sum=$(md5sum "$line") #echo "Local MD5Sum: ${local_md5sum}" #Calculate the MD5sum in remote machine remote_md5sum=$(ssh ${EWS_USER}@${EWS_HOST} "cd '$TGT_DIR' ; find -name '$filename' -exec md5sum {} \;" > ${LOG_NAME} put ${LOCAL_DIR}/${line} ${TGT_DIR}/${line} EOF But any idea how to use EXPECT here in the scenario below to make the connection passwordless? remote_md5sum=$(ssh ${EWS_USER}@${EWS_HOST} "cd '$TGT_DIR' ; find -name '$filename' -exec md5sum {} \;" < /dev/null)