asp.net - Digitally sign a PDF on the server -

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i have project generate pdfs on server using asp.net (c #). need customer able digitally sign these pdf. saw, documents must signed @ client side, using applet, in server have no access private key of certificate, said above, pdfs generated on server , keep them there.

so, need digitally sign pdfs on server, taking client's certificate.

thanks

since not possible or anyway safe extract , send client's private key, sign pdfs on server need establish "session" client , let them calculate signature.

the steps should like:

1- client sends public certificate embedded in signed pdf

2- server generates pdf, embeds certificate , calculates hash (eg: sha1)

3- server sends hash client applet

4- applet calculates digital signature private key

5- applet sends signature server

6- server embeds digital signature , closes pdf.

to itext have use preclose method after ambedding certificate, able alculate sha1 hash on final document. after pre-closing pdf have calculate hash of pdf , send client. careful: while preclosed have keep document in memory, example in server session.

to generate pdf, embed certificates , prepaare document can use itextsharp, c# port of itext library. calculate hash , create pkcs7 envelopes can use .net crypto api.

hope helps.


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