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[Adrian Johnson <ajohnson@xxxxxxxxxxx>]

(In reply to Adam Reichold from comment #77)
> Some minor suggestions:
> 
> * The naming of BLOCK_SIZE and block_len in hashSignedDataBlock seems
> misleading to me, maybe CHUNK_SIZE and block_len?
> 
> * The method hashSignedDataBlock could probably be replaced by a static
> function taking the stream and the handler? This should give the compiler
> more optimization possibilities than if it is visible in other translation
> units.
> 
> * I think the while loop within could become a for loop for better
> readability with the case reduced to computing the number of bytes to read
> instead of two separate calls to doGetChars and updateHash.

I don't think there is much benefit in making that function a static. It
is not something that is called a frequently from an inner loop.

I think the function would read better as "hashSignedByteRange" as "byte
range" is the terminology used in the PDF reference section in
signatures. Instead of setting the stream offset before calling this
function it would better easier to understand the code if the function
took an offset and length.

I agree that the two calls to doGetChars and updateHash should be merged
but I don't think a for loop is the best way to process loops where the
increment is not exactly the same on each iteration. Maybe something
like this:

  void FormFieldSignature::hashSignedByteRange(SignatureHandler *handler,
     Goffset start, Goffset len)
  {
    const int CHUNK_SIZE = 4096;
    unsigned char buffer[CHUNK_SIZE];
    Goffset i = 0;
    int byte_count = CHUNK_SIZE;

    doc->getBaseStream()->setPos(start);
    while (i < len)
    {
      if (i + CHUNK_SIZE > len)
        byte_count = len - i;

      doc->getBaseStream()->doGetChars(byte_count, buffer);
      handler->updateHash(buffer, byte_count);
      i += byte_count;
    }
  }

I renamed the "signed_data_buffer" to "buffer" as whenever I see
"signed" in C/C++ I think of the integer type. "unsigned char
signed_data_buffer" is confusing to read.

I would prefer the buffer be moved out to the class. It is better not to
allocate large buffers on the stack. We may later increase the buffer
size.

I don't mind if we fix all this later. It doesn't have to hold up the
initial release.

-- 
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https://bugs.launchpad.net/bugs/740506

Title:
  verify digital signatures

Status in Evince:
  Confirmed
Status in Poppler:
  Confirmed
Status in poppler package in Ubuntu:
  Triaged

Bug description:
  Binary package hint: evince

  This is a feature request to verify digital signatures.  I'm receiving more and more digitally signed PDF's and evince already acknowledges them with:
  Signature Not Verified
  Digitally signed by <signer>
  Date:  <time stamp>
  Reason: <reason>
  Location: <location>
  but it would be great if Evince would be integrated into the distro's ca-certificate infrastructure to verify these signatures.

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