Password tool website creation

We are looking to create a web-based password distribution tool, this would allow us to send users a link that would display a password for X amount of days or X amount of views. We would then like to have a similar system in reverse, generate a link for an end-user to input their password to be forwarded onto a specified email address.

As with the nature of passwords, we would want this to be secure, as such, the below would be required.
-The database must be encrypted securely.
-The links generated and must be 'un-guessable'.

The key for this tool will be simplicity for the end-users, we want to make this as easy to use as possible.

Provided this goes well, we would be looking to add items to this further.