[iText-questions] Signing & Encrypting

[Wahaj]

Hi Guys,

 

I have been playing with iText signing and encryption functionality for some time and below are my obervations using iText-50

 

• For multiple signings to work the last parameter MUST be set to true other wise signing again will corrupt the previous signatures.

                PdfStamper stp = PdfStamper.createSignature(reader, fout, '\0', new java.io.File("temp1"), true);

• For Sign & Encrypting a PDF that parameter MUST be set to 'false', other wise an exception will come i.e.

com.lowagie.text.DocumentException: Append mode does not support encryption.

 at com.lowagie.text.pdf.PdfStamper.setEncryption(PdfStamper.java:302)

 at com.lowagie.text.pdf.PdfStamper.setEncryption(PdfStamper.java:322)

PdfStamper stp = PdfStamper.createSignature(reader, fout, '\0', new java.io.File("temp1"), false);

• While signing and encrypting using the 'false' parameter as above the previous signature if present gets corrupted. A more detailed result is as follows:

PDF document state         Action to Perform               Are Previous signatures get corrupted ?

-----------------------------------------------------------------------------------------------------------------------------------------

Sign&Enc                               Sign                                       YES

Sign                                       Sign&Enc                               YES

Enc                                        Sign&Enc                               No

Enc                                        Sign                                       No

Q1) Can we do some thing to change YES to No in the above table ?

 

Q2) Also is there an easy way to figure out whether a PDF document is already encrypted without catching certain exceptions ?

 

Regards,

Wahaj