Readable Font that is Web Safe

Question

In a web app I work with from time to time the issue of text readability has come up. The reason is that it involves passwords which will be read off of the web page or written down. One of my co-workers pointed out the Crystal font as one that is designed to be unambiguous ("l" and "1" aren't confused, "0" and "O", etc), but I'm pretty sure its not useful on the web. I realize that I will probably have to use a fallback strategy, but am looking for advice on what fonts are good for this purpose and specifically those fonts that users may have available. Also, links to resources on the topic would be great as well. Thanks!

Edit: People have suggested monospace as a readable web font. Can anyone provide additional info on possible fonts that users might have that may be better than monospace so that I can chain fonts together to get the best possible result?

Answer 1

A great start is font-family: monospace. These fonts are designed to be unambiguous.

If you're really desperate to get it exactly right, you can render a little image in your chosen font on the server, then send that.

Answer 2

If readability is the most important thing for the password and you are required to have a specific font you can draw the text on an image on the server using your specific font then serve it to the browser.