Fix #1585: handle /P permissions written as unsigned int32 in encrypted PDFs#1592
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Fix #1585: handle /P permissions written as unsigned int32 in encrypted PDFs#1592andreasrosdalw wants to merge 1 commit into
andreasrosdalw wants to merge 1 commit into
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PDFs encrypted with RC4 40-bit by producers like mPDF store the /P permissions entry as an unsigned 32-bit integer (e.g. 4294963412) instead of the signed value required by ISO 32000 (-3884). PdfNumber stores values as double, and the direct double-to-int cast in intValue() clamps values above Integer.MAX_VALUE to Integer.MAX_VALUE (JLS 5.1.3) instead of preserving the bit pattern. The wrong /P value was fed into the MD5 that derives the RC4 key, so PdfReader threw BadPasswordException even though the user password was empty and every other reader (Acrobat, qpdf, PDFBox, Evince) opens the file. Convert through long to get two's complement wrapping, matching how other readers interpret out-of-range integers. Values in the signed 32-bit range are unaffected. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Summary
Fixes #1585.
PDFs encrypted with RC4 40-bit (R=2, V=1) by producers like mPDF threw
BadPasswordException: Bad user passwordeven with an empty user password, while Acrobat, qpdf, PDFBox and Evince all open the same files fine.Root cause
mPDF writes the
/Ppermissions entry as an unsigned 32-bit integer (e.g.4294963412) instead of the signed value required by ISO 32000 (-3884) — the bit pattern is identical.PdfNumberstores values asdouble, andintValue()did a direct(int) valuecast. Per JLS §5.1.3, a double-to-int cast clamps values aboveInteger.MAX_VALUEto2147483647rather than wrapping, so thepValuefed into the MD5 that derives the RC4 key was wrong and no longer matched the/Uentry.Fix
4294963412now converts to-3884as other readers do. All values in the signed 32-bit range are unaffected (including fractional truncation semantics).Tests
New
PdfNumberTest:intValueWrapsUnsignedInt32— the mPDF value4294963412 → -3884, plus4294967292 → -4and2147483648 → Integer.MIN_VALUE. Fails on master, passes with the fix.intValueUnchangedForSignedRange— guards existing behavior for normal, boundary and fractional values.Full
openpdf-coresuite passes: 2086 tests, 0 failures — confirming nothing relied on the old clamping behavior.