如何保护网页字体？

Question

my client has bought a font which I would like to use on his website, but the company which made the font(Adobe) told me, that there is no webfont service for this current font and I can use it on a website only if I rasterize it or make it impossible to download/steal the font in any other way.

Therefore, the question is:

Is there any reliable way to protect webfonts?

(second, optional part)

Is there any way that is generally considered to be enough so its legally safe to use the font?

What I learned so far:

1) I heard about Cufon, which uses SVG files, which are(according to w3.org) intended for this purpose:

The purpose of SVG fonts is to allow for delivery of glyph outlines in display-only environments. SVG fonts that accompany Web pages must be supported only in browsing and viewing situations. Graphics editing applications or file translation tools must not attempt to convert SVG fonts into system fonts. The intent is that SVG files be interchangeable between two content creators, but not the SVG fonts that might accompany these SVG files. Instead, each content creator will need to license the given font before being able to successfully edit the SVG file.

But I also saw few online converters from SVG to normal font formats(havent really tried them).

2) I also saw this thread, which says its not completely possible, but its two years old, maybe the technologies have advanced.: How to protect WebFonts

3) I also believe the PDF has some way to make it impossible to extract font, few years ago I saw PDF from which I couldnt extract the text(even with use of 3rd party tools) because there were deliberately messed font tables inside so I had to render the whole document to image and use OCR. However, this might not be the case since I was trying to extract the text and not the font.

4) Font selling companies have to protect their fonts somehow (?)

Answer 1

Fundamentally, if you're going to use the font without using images (which is a horrible practice and should be avoided if you're talking about more than a few characters on the page!) you cannot stop people from reverse engineering your fonts. For instance, processing them as SVG to canvas (or SVG to VML) as Cufon does will force users to do some work if they want to steal it, but there are plenty of SVG->TFF converters out there.

Even without a converter you could still create a new font set based on the vectors defined by SVG. The only way to prevent this is to not provide any vector-based font system (i.e. use bitmaps), but that basically destroys the accessibility of your site. And even then, if you've written a dynamic system for serving image-based fonts, if you let the user have a sufficiently high resolution bitmap of the image (i.e. server a large font), there are scripts available that will convert outlines to vectors.

Font-selling companies (at least the ones I've seen) all serve only image-based versions of their fonts for previews, and cap the maximum size of the font that you can demo.