![]() The /AcroForm contains /SigFlags 3 and /Fields, where x is the id of a /Type/Annot with /Subtype/Widget. I've tried putting it both in place and as a reference, but that makes no difference. In the /Type/Catalog dictionary, I have an /AcroForm. The question is what the reason is for this difference, and if there are any tools that can give a more detailed explanation of what is wrong? This gives the same "This signature is invalid." error message as above, but it still shows "The signer's identity is valid", as well as showing the Hash Algorithm as "SHA1". To find the minimal additions needed, I've cleared one PDF tag after another, carefully not changing the offset for the remaining tags. After telling it to accept my self signed certificate, it displays a nice green checkbox for the signature. ![]() The PDF from JSignPdf is correct, according to Acrobat Reader. On the "Advanced Signature Properties", the Hash Algorithm is "Not available". When opening "Signature Properties" it says "This signature is invalid because there are errors in the formatting or information contained in this signature". In the Signature Panel it says "Signed by Unknown" instead of using the correct name from the key. I've gotten Acrobat Reader to acknowledge that there is a signature in the file, but something is still wrong. Sorry for not making this clear in my initial post. Starting with a working example is often the easiest way for me to understand how everything fits together. I have indeed also read both the PDF Reference for 1.7 and the "32000" specification linked below, but sometimes I get a bit lost by the number of references. I've checked the Digitally sign PDF files question, but the comments there seemed to conclude that one should use iText instead of trying to do it yourself. I started with a minimal PDF, signed it with JSignPdf, and am now trying to get my own program to produce a file that Adobe Acrobat Reader will interpret identically. I have a PDF generator written in C, and now I want to add digital signatures to it.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |