API for write-protected Calc or Writer ?

[B Marcelly]

Hello,
Since OpenOffice.org version 3.3 it is possible to have a password protecting a Calc or Writer document from modifications. Such document can be read, not modified.
See new features and see this announce.

If you open by program a document protected from modifications, you can modify it, but the store() method throws an exception.

I have searched for an API that would allow to :
- protect from modifications a document by setting a password
- save the document with same password protection after it has been modified by program.

I could not find any new API feature. There is nothing new in the IDL description of MediaDescriptor.
Maybe someone that can read source codes could find out if such API exists or not ?

Flame icon removed. That icon means 'Tagged to a known issue' (TheGurkha, Moderator)

[hanya]

Hi,
It seems it is not documented yet. I found the following way in the source code [1]:

Code: Select all

sub StoreWithModifyPassowrd
  Dim info(3) As new com.sun.star.beans.PropertyValue
  info(0).Name = "algorithm-name"
  info(0).Value = "PBKDF2"
  info(1).Name = "salt"
  info(1).Value = Array(107,118,-86,-63,19,7,-93,-63,-127,-38,-40,2,120,-32,-66,94)
  info(2).Name = "iteration-count"
  info(2).Value = 1024
  info(3).Name = "hash"
  info(3).Value = Array(-84,-89,22,-88,116,126,-48,-86,41,-70,-103,-5,52,84,52,24)

  Dim args(0) As new com.sun.star.beans.PropertyValue
  args(0).Name = "ModifyPasswordInfo"
  args(0).Value = info

  ThisComponent.storeAsURL(_
    "file:///home/user/Desktop/u1.odt", args)
end sub

salt and hash are generated from password in [2] and the function is not accessible though API. These values are taken by macro recorder in the above code.

[1] http://svn.services.openoffice.org/open ... l.cxx#2864
[2] http://svn.services.openoffice.org/open ... per.cxx#83

[B Marcelly]

Thank you for your investigation, hanya !

Your code is a complex alternative to the absence of an API. I have created Bug 119086 to request a real API.

Regards

[anasrallah]

were you able to get a solution for this?
I'm trying to do a storeasurl with password on edit but with no luck

Thanks

[anasrallah]

in fact what's the password that generated the salt and the hash above?

how can i generate my own salt and hash (one time)


Thanks

[RoryOF]

The password is given in Hanya's reference [2]

If you can't work it out you should question if you should be attempting to use code at this level.

[anasrallah]

I could probably if I want to it's just I was looking for a quick answer...
I just translated 2000 lines of code from vba to python-uno/OOBasic (no previous knowledge in python or OOBasic) and didn't want to defer my focus in building a utility or learn the OO framework for a simple feature I was looking for.
on a different day I wouldn't mind digging in or even contribute to this project, but for now any help would be greatly appreciated.

[anasrallah]

ok so I'm generating the salt and hash from recording a macro using my own password, when I run the code posted by hanya with the generated salt/hash and then I try to open the file and try to edit, i'm being asked for a password but my original password does not work...
what am I doing wrong here

Thanks

[hanya]

i'm being asked for a password but my original password does not work...
what am I doing wrong here

Try this function to help conversion of the salt and hash:

Code: Select all

Sub ByteSeqToIntSeq(a)
  for i = 0 to ubound(a) step 1
    v = a(i)
    if v < 0 then
      a(i) = &H100 + v
    end if
  next
End sub

[anasrallah]

Hanya, thanks for the response.

I tried the conversion as per your function but this didn't help, I still cannot edit the saved odt.

here is my block of code

dim salt
dim hash
salt = Array(-76,46,-73,112,-50,31,76,47,-39,-26,89,-29,111,113,-92,-93)
ByteSeqToIntSeq(salt)
hash = Array(102,-105,33,31,104,-35,115,63,-118,-86,11,-40,46,19,-124,-71)
ByteSeqToIntSeq(hash)

Dim info(3) As new com.sun.star.beans.PropertyValue
info(0).Name = "algorithm-name"
info(0).Value = "PBKDF2"
info(1).Name = "salt"
info(1).Value = salt
info(2).Name = "iteration-count"
info(2).Value = 1024
info(3).Name = "hash"
info(3).Value = hash



Dim args(1) As new com.sun.star.beans.PropertyValue
args(0).Name = "ModifyPasswordInfo"
args(0).Value = info
args(1).Name = "Overwrite"
args(1).Value = True
ThisComponent.storeAsURL(ThisComponent.URL, args)

[hanya]

My apologies, so it should be work now, pass it like as follows:

Code: Select all

info(1).Name = "salt"
  info(1).Value = CreateUnoValue("[]byte", (Array(13,92,-41,.....-92,36))

I wonder these values are stored in settings.xml file in ODF file and the contents of the file are not encrypted. So someone can remove the part and to modify the document. The purpose of this passoword is to protect the document from easy modification...?, I don't konw.

[anasrallah]

Perfect now it works. Thanks for the help.