PHP in post is much more secure than Visual Basic directly connecting to the database.
PHP should be just fine, you'd be running it like a website,
Application Sends Login Data (Pre-MD5 hashed, etc.) => PHP Gets data => PHP Relays data via Localhost (for the users remote host) to the Database => PHP relays the results back to the application (encrypted or not, up to you.)
PHP should be just fine, you'd be running it like a website,
Application Sends Login Data (Pre-MD5 hashed, etc.) => PHP Gets data => PHP Relays data via Localhost (for the users remote host) to the Database => PHP relays the results back to the application (encrypted or not, up to you.)

