Re: [Podofo-users] PDF signature
A PDF parsing, modification and creation library.
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From: Josep M. T. <jm...@c3...> - 2007-03-14 10:14:37
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On Tue, 2007-03-13 at 16:01 -0400, Leonard Rosenthol wrote: > On Mar 13, 2007, at 12:22 PM, Josep Mones Teixidor wrote: > > > I need to sign PDF files using ordinary or MDP signatures along with > > ByteRange or, if possible, ObjectDigest. I need to do that from a > > Windows CE environment, so I'm considering C and C++ possibilities, as > > PoDoFo. > > > ByteRange signatures are MUCH simpler to implement than MDP/ > ObjDigest ones. So if you have a choice - go with them! > > > > As I see from the code, the library doesn't support signature. Am I > > right? > > > Correct. > > > > I'd be willing to add this feature to PoDoFo, but I'd need to > > assess how > > much work I'd need to do that. Can this feature easily be added to the > > library? > > > > ASSUMING that you have a comprehensive crypto library available to > handle the complexities of hashing, signing and certificate > management - PoDoFo is complete enough to enable you to build a > solution. Using something like openssl, cryptlib or crypto++ (on a > desktop/server machine), adding byte range signatures to PoDoFo > wouldn't take more than a couple of days of work - assuming someone > familar with DigSig technology and low level PDF work. If you're > not familiar with one or the other, than add accordingly. > > > Leonard > Leonard, Thank you very much for your answer... It has been very helpful. Our company is a smart card reader manufacturer and we have lots of experience in the digital signature field. However we don't have such experience in the PDF field, but we can handle it ;) I see that no extra libraries are used, and porting to MS Windows is already done. So i expect porting to Windows CE should be easy, shouldn't it? We will use this for a project for a customer, so I can't say now that we'll surely make this in the future. We depend on their decision. If we finally do this modification and if you think it would be a nice addition to PoDoFo, we'll work to do this in PoDoFo "style". Since we need windows, we'll probably need to use CryptoAPI (because we want to enable a solution to smart card users and certificates are usually in CryptoAPI or PKCS#11 must be used). Perhaps it would be a a good solution to make an API that's able to extract a hash (or data to be hashed), and then to introduce a signature, since I imagine you don't want to stick to CryptoAPI ;) Or we could just make a system that has multiple backends (but it would be a little bit difficult to make a unique API to that, in order to select signing certificates). Anyway, we can discuss that later. Thank you again for all the information! Regards, -- Josep Monés jm...@c3... C3PO, S.L. http://www.c3po.es C/ Bertran, 113 - 08023 Barcelona Tel. 93 417 99 55 - Fax 93 253 12 80 |