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https://issues.apache.org/jira/browse/PDFBOX-1694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13741085#comment-13741085
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Peter Costello commented on PDFBOX-1694:
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The example I sent decodes properly. The point is that the encoding &
decoding should be symmetrical. The decoding adds padding bytes "~!!" or
93*85^n where n is extra number of bytes. The spec is to add
84*85^n+84*85^(n-1)+84*85^(n-2). Whether or not the current decoding works
would need to be verified by writing a test program that encodes and then
decodes all 2^32 possible data values. My contention is that it would be
simpler to just fix the code rather than waiting for some obscure bug
report that is difficult to debug. Your call.
On Thu, Aug 15, 2013 at 12:32 AM, Andreas Lehmkühler (JIRA) <[email protected]
> Bug in org.apache.pdfbox.io.Ascii85InputStream
> ----------------------------------------------
>
> Key: PDFBOX-1694
> URL: https://issues.apache.org/jira/browse/PDFBOX-1694
> Project: PDFBox
> Issue Type: Bug
> Affects Versions: 1.7.1
> Environment: Any
> Reporter: Peter Costello
> Labels: Ascii85Decode
> Original Estimate: 0.5h
> Remaining Estimate: 0.5h
>
> Method 'org.apache.pdfbox.io.Ascii85InputStream.read()' has bug when reading
> final set of char that are not modulo-4.
> Test
> file="www.mzweb.com.br/grupobimbo/web/arquivos/Bimbo_Historia_20070409_Esp.pdf".
>
> On page#0 there is a dictionary "323 0 obj << /Length 1492 /Filter
> [/Ascii85Decode /FlateDecode]>>"
> Last set of bytes to decode is "%f" or 0x25, 0x66
> Ascii85InputStream pads this to "%f~!!" and correctly generates the final
> byte 0x0f.
> Including the '~' end-of-data char in the padding is a major bug.
> If the final padding were "%f!!!", the final byte decoded would be 0x0e
> (which is wrong).
> The correct padding is the 'u' char, or "%fuuu" (See
> http://en.wikipedia.org/wiki/Ascii85)
> This is a quick fix.
> The PDF files for corporate website "Grupo Bimbo" include lots of examples
> using Ascii85Decode/
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