Re: Disable copy and paste
On 08/08/2013 06:31 AM, Rainer M Krug wrote: Ray Rashif writes: On 8 August 2013 17:51, Rainer M Krug wrote: Just one word of caution: if you can see the text on screen, you can extract it by taking a screenshot and using ocr (optical character recognition) and nothing will stop you. So this just makes it slightly more difficult to get the text. What's more, if I'm not wrong, encryption depends on the reader having support, so you can effectively render encryption useless by using a very old reader and PDF format. Even GhostScript lets you bypass encryption, though not intentionally. I might be wrong, but I think even okular had an option (!) to enable or disable to respect the restrictions. Yes, that was true at one point. And I assume if one complied the source oneself, one could pretty easily disable encryption. Richard
Re: Disable copy and paste
Ray Rashif writes: > On 8 August 2013 17:51, Rainer M Krug wrote: >> Just one word of caution: if you can see the text on screen, you can >> extract it by taking a screenshot and using ocr (optical character >> recognition) and nothing will stop you. So this just makes it slightly >> more difficult to get the text. > > What's more, if I'm not wrong, encryption depends on the reader having > support, so you can effectively render encryption useless by using a > very old reader and PDF format. Even GhostScript lets you bypass > encryption, though not intentionally. I might be wrong, but I think even okular had an option (!) to enable or disable to respect the restrictions. > > It's really all about preventing frequent abuse of documents by lay > people. Someone with the intent _will_ get your text somehow or > another. There are many tools that person could employ. Absolutely - but I think the problem are not the lay people, but rather the "expert copier" who knows how to do it. Cheers, Rainer > > > -- > GPG/PGP ID: C0711BF1 > -- Rainer M. Krug email: RMKruggmailcom
Re: Disable copy and paste
On 8 August 2013 17:51, Rainer M Krug wrote: > Just one word of caution: if you can see the text on screen, you can > extract it by taking a screenshot and using ocr (optical character > recognition) and nothing will stop you. So this just makes it slightly > more difficult to get the text. What's more, if I'm not wrong, encryption depends on the reader having support, so you can effectively render encryption useless by using a very old reader and PDF format. Even GhostScript lets you bypass encryption, though not intentionally. It's really all about preventing frequent abuse of documents by lay people. Someone with the intent _will_ get your text somehow or another. There are many tools that person could employ. -- GPG/PGP ID: C0711BF1
Re: Disable copy and paste
Ray Rashif writes: > On 8 August 2013 16:17, Rilke Rainer Michael wrote: >> Hi List, >> >> >> >> I want to export a lyx document to a pdf. However, I want also that once >> reading the document it is impossible to copy and paste text from this pdf. >> Do you have any idea, whether there is a workaround for lyx? Just one word of caution: if you can see the text on screen, you can extract it by taking a screenshot and using ocr (optical character recognition) and nothing will stop you. So this just makes it slightly more difficult to get the text. As far as I remember, one can also convert the pdf to images, and do the ocr automatically. Same with images - if they can be displayed, they can be extracted. > > That is encryption. You have the choice of disabling printing as well. > Converting to images, or rasterizing fonts, has the same effect as not > allowing copies but greatly increases the file size. However, this is > a standalone process, separate from LyX. I use PDFtk on GNU/Linux. [1] > pdftk is an excellent tool for doing this. You could even add it as a copier into lyx to automatically encrypt - if you really want to. Cheers, Rainer > [1] http://www.pdflabs.com/docs/pdftk-cli-examples/ > > > -- > GPG/PGP ID: C0711BF1 > <#secure method=pgpmime mode=sign> Footnotes: [1] -- Rainer M. Krug email: RMKruggmailcom
Re: Disable copy and paste
On 8 August 2013 16:17, Rilke Rainer Michael wrote: > Hi List, > > > > I want to export a lyx document to a pdf. However, I want also that once > reading the document it is impossible to copy and paste text from this pdf. > Do you have any idea, whether there is a workaround for lyx? That is encryption. You have the choice of disabling printing as well. Converting to images, or rasterizing fonts, has the same effect as not allowing copies but greatly increases the file size. However, this is a standalone process, separate from LyX. I use PDFtk on GNU/Linux. [1] [1] http://www.pdflabs.com/docs/pdftk-cli-examples/ -- GPG/PGP ID: C0711BF1
Re: Disable copy and paste
On 8 aug. 2013, at 10:17, Rilke Rainer Michael wrote: > Hi List, > > I want to export a lyx document to a pdf. However, I want also that once > reading the document it is impossible to copy and paste text from this pdf. > Do you have any idea, whether there is a workaround for lyx? > Basically you want DRM. Which is silly at best.