Changeset 767

Timestamp:

12/12/06 22:11:22 (2 years ago)

Author:

mfenniak

Message:

Making headway with encryption. For rev 2 files only, user and owner passwords can be authenticated. Next stop: rev 3 files.

Files:

• pypdf/trunk/pyPdf/pdf.py (modified) (2 diffs)

pypdf/trunk/pyPdf/pdf.py

@@ -532 +532 @@
-        #    if document metadata is not being encrypted, pass \xff\xff\xff\xff into hash
-        md5_hash = m.digest()
-
-
-
-
-
+#
+#
+#
+#
+#
-        return md5_hash[:keylen]
-
@@ -547 +547 @@
-        return U
-
+    def _alg33_1(self, password):
+        import md5
+        m = md5.new()
+        password = (password + self._encryption_padding)[:32]
+        m.update(password)
+        # alg 3.3 step 3 goes here, but isn't here yet
+        md5_hash = m.digest()
+        key = md5_hash[:5]
+        return key
+
-    ##
-    # Decrypt file.
-    def decrypt(self, password):
+        user_password = self._authenticateUserPassword(password)
+        if user_password:
+            print "User password accepted"
+        else:
+            key = self._alg33_1(password)
+            # rev 2 only
+            encrypt = self.safeGetObject(self.trailer['/Encrypt'])
+            real_O = self.safeGetObject(encrypt["/O"])
+            userpass = utils.RC4_encrypt(key, real_O)
+            owner_password = self._authenticateUserPassword(userpass)
+            if owner_password:
+                print "Owner password accepted"
+            else:
+                print "Password auth failed."
+
+    def _authenticateUserPassword(self, password):
+        encrypt = self.safeGetObject(self.trailer['/Encrypt'])
+        real_U = self.safeGetObject(encrypt['/U'])
-        U = self._alg34(password)
-print "calc U: %r" % 
-
+return U == real_
+
-
-def getRectangle(self, name, defaults):