Password set for DocumentProtection not accepted in MSWord

[McPeter]

I try to protect a Word document to READ Only mode using the docx4java API. Using the following code;

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                CTDocProtect cdtP = new CTDocProtect();
                cdtP.setEnforcement(Boolean.TRUE);
                cdtP.setEdit(STDocProtect.READ_ONLY);
               
                // Set password for protection               
                String password = "aaaa" ;

                Random rnd = new SecureRandom();
                int spins = 100000 ;
                int keylength = 256 ;
                byte[] salt = new byte[16];
                rnd.nextBytes(salt);
                byte[] hash = new byte[0] ;
                hash = password.getBytes() ;
               
           
                cdtP.setCryptProviderType(STCryptProv.RSA_FULL);
                cdtP.setCryptAlgorithmClass(STAlgClass.HASH);
                cdtP.setCryptAlgorithmType(STAlgType.TYPE_ANY);
                cdtP.setCryptAlgorithmSid(BigInteger.valueOf(4));
                cdtP.setCryptSpinCount(BigInteger.valueOf(spins));

                cdtP.setHash(hash);
                cdtP.setSalt(salt);
               
                // set document protection
                dsp.getContents().setDocumentProtection(cdtP);

When opening the Word document it is protected and a password is asked the expected password seems not to match the password used in the code "aaaa".
Any idea what is not correct in the code ?

Cheers,

Peter

== Update 1 ==

When setting the hash and the salt using the value of password

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      hash = password.getBytes() ;               
                salt = password.getBytes() ;

And printing the hash and salt

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           System.out.println("Hash: " + new String(hash)) ;
           cdtP.setHash(hash);
           System.out.println("Salt: " + new String(salt)) ;
           cdtP.setSalt(salt);

The salt and hash seem to be ok;

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Protection is enabled , protection mode is READ_ONLY
Hash: aaaa
Salt: aaaa


What seems to be odd is that the salt and hash in the settings.xml is the same. I would expect that the hash and salt in the settings.xml would differ (Hashed pasword would be salted using salt value)

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w:hash="YWFhYQ==" w:salt="YWFhYQ=="/

== Update 2 =

Also tried to create a hash using the salt value using the following method;

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public static byte[] hash(char[] password, byte[] salt, int iterations, int keylength) {
    PBEKeySpec spec = new PBEKeySpec(password, salt, iterations, keylength);
    Arrays.fill(password, Character.MIN_VALUE);
    try {
        for (Object obj : java.security.Security.getAlgorithms("Cipher")) {
         System.out.println(obj);
    }
    SecretKeyFactory skf = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
    System.out.println(skf.generateSecret(spec).getEncoded()) ;
      return skf.generateSecret(spec).getEncoded();
    } catch (NoSuchAlgorithmException | InvalidKeySpecException e) {
      throw new AssertionError("Error while hashing a password: " + e.getMessage(), e);
    } finally {
      spec.clearPassword();
    }
}

[jason]

Please see https://github.com/plutext/docx4j/blob/ ... ected.java

Note: docx4j v3.3.0 or later

[McPeter]

That example is about protecting a paragraph. In the example i gave the whole document is protected.
The issue is that i was not able set the correct hash and salt.

[jason]

My understanding is in terms of Word's UI, you can

- Protect Document > Restrict Editing > No changes (Read only)

- Protect Document > Encrypt with Password

CreateDocxProtected, where it says:

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    ProtectDocument protection = new ProtectDocument(wordMLPackage);
    protection.restrictEditing(STDocProtect.READ_ONLY, "foobaa");


is an example of the former.

To do the latter, you:

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      Docx4J.save(wordMLPackage, new java.io.File(filename), Docx4J.FLAG_SAVE_ENCRYPTED_AGILE, "some password");


and the resulting file will be an OLE compound file.

I'm not aware of some third option you are alluding to?

[McPeter]

Hi Jason,

docx4j has the setHash and setSalt methods on CTDocProtect to set the password. Only there seem to be no Crypto classes available to create the correct hash and salt.
I 'borrowed' those from the other docx Java API, POI. Here an example.

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            // Get settings.xml part of docx
            WordprocessingMLPackage wordMLPackage = Docx4J.load(new java.io.File(filename));
            MainDocumentPart mdp = wordMLPackage.getMainDocumentPart();
            Relationship rs = mdp.getRelationshipsPart().getRelationshipByType(Namespaces.SETTINGS);
            DocumentSettingsPart dsp = (DocumentSettingsPart) mdp.getRelationshipsPart().getPart(rs);

            // Create CTDocProtect instance and configure it for Enforcing read-only
            CTDocProtect cdtP = new CTDocProtect();
            cdtP.setEnforcement(Boolean.TRUE);
            cdtP.setEdit(STDocProtect.READ_ONLY);

            SecureRandom random = new SecureRandom();
           
            // Set password for protection   
            String password = new BigInteger(130, random).toString(32);
            result.setPassword(password);
               
            byte salt[] = random.generateSeed(16);
            int spins = 100000;
            HashAlgorithm hashAlgorithm = HashAlgorithm.sha1;
            String legacyHash = CryptoFunctions.xorHashPasswordReversed(password);
            byte hash[] = CryptoFunctions.hashPassword(legacyHash, hashAlgorithm, salt, spins, false);

            cdtP.setCryptProviderType(STCryptProv.RSA_FULL);
            cdtP.setCryptAlgorithmClass(STAlgClass.HASH);
            cdtP.setCryptAlgorithmType(STAlgType.TYPE_ANY);
            cdtP.setCryptAlgorithmSid(BigInteger.valueOf(4));
            cdtP.setCryptSpinCount(BigInteger.valueOf(spins));

            cdtP.setHash(hash);
            cdtP.setSalt(salt);

            // set document protection
            dsp.getContents().setDocumentProtection(cdtP);

[McPeter]

Tried your suggestion to save a Docx with an password.

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Docx4J.save(wordMLPackage, new java.io.File(filename), Docx4J.FLAG_SAVE_ENCRYPTED_AGILE, "some password");

The attribute FLAG_SAVE_ENCRYPTED_AGILE seems not to exist in docx4j version 3.2.2.

[jason]

Everything I have said in this thread is wrt docx4j v3.3.0, which repackages some POI code; see https://github.com/plutext/docx4j/tree/ ... apache/poi

and builds on that.