PDF多重数字标牌 [英] PDF Multiple Digital sign
问题描述
我在另一篇
或使用支持PDF的付费解决方案（如PDFTron）
https://www.pdftron.com/documentation/samples/php/DigitalSignaturesTest
原始版本
这只能通过增量更新来完成，该更新允许添加新的部分，而无需修改以前签署的原始文档。参见7.5.6节（PDF格式规范）：
https://www.adobe.com/content/dam/acom/zh-cn/devnet/acrobat/pdfs/PDF32000_2008.pdf
TCPDF不支持增量更新。请参阅帮助论坛问题：
https://sourceforge.net/p/tcpdf/discussion/435311/thread/8cf24d19/
您需要使用支持增量更新的库。一旦此类库被来自NodeJS世界的SignPDF 。这是讨论了多个签名的问题单。也许您可以将此作为后端服务，仅用于为应用程序的这一部分应用签名。
I visit into a similar issue in another post. Using FPDI and TCPDF I can sign a PDF document with a signature without problems, but when it comes to multiple signatures the previous signature remains unformatted and only the last signed is valid. Solution can you recommend me?, Thanks.
UPDATE
I was checking the latest version of the TCPDF code and see that setSignature() has a paramater called $approval. If it sets to 'A' , the code does different processing for the digital signature and the parameter descriptions suggests it is for incremental update (i.e. @param $approval (string) Enable approval signature eg. for PDF incremental update). I haven't seen that value being mentioned in the documentation. Try using that for additional signatures after the first one.
Or use a paid solution like PDFTron, which supports PDF
https://www.pdftron.com/documentation/samples/php/DigitalSignaturesTest
ORIGINAL VERSION
This can only be done through incremental update, which allows appending new section without modifying the original document that's been signed previously. See section 7.5.6 in PDF format spec:
https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/PDF32000_2008.pdf
TCPDF does not support incremental update. See the help forum question:
https://sourceforge.net/p/tcpdf/discussion/435311/thread/8cf24d19/
You need to use a library that supports incremental update. Once such library is SignPDF from NodeJS world. Here is the issue ticket that's been discussed multiple signatures. Maybe you can have this as a back-end service just for applying signatures for this portion of your app.
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