Somebody sent me a encrypted PDF to ask me help decrypt, I tried pdfcrypt, it got error. and when used pdfcrack, got the following warning messages,

WARNING: O-String != 32 Bytes: 33
WARNING: U-String != 32 Bytes: 33


After studied the source code of iTextSharp, I noticed it is a bug of iTextSharp in SetupGlobalEncryptionKey method of the PdfEncryption class,
misused the this.ownerKey and ownerKey and we can only find this bug when the PDF has strange length of ownerkey/userkey, for example 33, not 32.

this.documentID = documentID;
//this.ownerKey = ownerKey;
Array.Copy(ownerKey, 0, this.ownerKey, 0, 32);
this.permissions = permissions;
// use variable keylength
mkey = new byte[keyLength / 8];

//fixed by ujihara in order to follow PDF refrence
md5.Reset();
md5.BlockUpdate(userPad, 0, userPad.Length);
//md5.BlockUpdate(ownerKey, 0, ownerKey.Length);
md5.BlockUpdate(this.ownerKey, 0, this.ownerKey.Length);


Then I review iText 5.1.1 and find it has the same bug:

this.documentID = documentID;
//this.ownerKey = ownerKey;
System.arraycopy(ownerKey, 0, this.ownerKey, 0, 32);
this.permissions = permissions;
// use variable keylength
mkey = new byte[keyLength / 8];

// fixed by ujihara in order to follow PDF reference
md5.reset();
md5.update(userPad);
//md5.update(ownerKey);
md5.update(this.ownerKey);


Today I got a email from my customer, he said when he ran DB2PDFX on Windows 7, he got the following message,
System.InvalidOperationException:The 'Microsoft.Jet.OLEDB.4.0' provider is not registered on the local machine

After some search, I found the solution,

If you try and open an access database on a 64bit os you will get the following error. System.InvalidOperationException: The ‘Microsoft.Jet.OLEDB.4.0′ provider is not registered on the local machine. To prevent this open My Project -> compile -> advanced compiler options and set the target cpu to x86.

Otherwise get the new redistributable

http://www.microsoft.com/downloads/en/details.aspx?FamilyID=C06B8369-60DD-4B64-A44B-84B371EDE16D&displaylang=en

Sumatra PDF 1.5 released on Apr 23, 2011, and includes more important features,

• add support for viewing XPS documents
• add support for viewing CBZ and CBR comic books
• add File/Save Shortcut menu item to create shortcuts to a specific place in a document
• add context menu for copying text, link addresses and comments. In browser plugin it also adds saving and printing commands
• add folder browsing (Ctrl+Shift+Right opens next PDF document in the current folder, Ctrl+Shift+Left opens previous document)

btw,
Last week, I noticed MuPDF trunk adds XPS support, but still has some bugs in windows registers.