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kovidgoyal · 08-05-2009, 04:49 PM

Adobe has a scheme to "encrypt" the fonts embedded in an EPUB file (this is independent of DRM). Their encryption is not really encryption (it just involves XOR the first kilobyte of the font files and is trivially reversible (5 lines of code). It has to be, to allow reading software to use the embedded fonts.

But I believe, they think this makes the fonts "non recoverable" at least legally.

IIRC, the IDPF even adopted a (trivially modified) version of this scheme.

08-05-2009, 04:49 PM	#8
kovidgoyal creator of calibre Posts: 43,858 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Adobe has a scheme to "encrypt" the fonts embedded in an EPUB file (this is independent of DRM). Their encryption is not really encryption (it just involves XOR the first kilobyte of the font files and is trivially reversible (5 lines of code). It has to be, to allow reading software to use the embedded fonts. But I believe, they think this makes the fonts "non recoverable" at least legally. IIRC, the IDPF even adopted a (trivially modified) version of this scheme.