Acrobat not validating signature with three pairs of ByteRange values

Question

I have created a PDF with a Digital signature, when opened with Acrobat Reader 10 i see the signature not bieng validated with a message saying, "There are errors in the formatting or information contained in this signature (support information: SigDict /ByteRange value)". My signature's byterange  contains three pairs of integers(/ByteRange[0 569 6417 400 6817 1013]) which seems to be causing this problem. Will appreciate any input regarding this.

Answer 1

Hi SindhuCT,
I can't speak for PDF-XChange Viewer as to whether or not they are correctly processing the signature. The only thing I can point out is you are hashing the bytes from the beginning of the file (byte 0) to byte 569. Then you are leaving a hole for the signature from byte 570 through byte 6416. You are then hashing from byte 6417 and marching off another 400 bytes which gets you to byte 6817. Finally you are telling Acrobat/Reader to leave a hole from byte 6817 to the end of the file at byte 7830. The problem is your got byte 6817 on both sides of the fence, as part of the signed data and as part of the second unsigned portion of the file. That's probably where your problem lies.
Yes, the PDF specification does say you can include other ranges, but it also says that it's not recommended because you are not going to be checking for all changes to the document. The specification says you should sign the entire file, less the hole for the signature contents.
Steve