[Pymoul-svn] SF.net SVN: pymoul: [284] pymoul/trunk/src/moul/crypt/stream.py

[<ti...@us...>]

Revision: 284
          http://pymoul.svn.sourceforge.net/pymoul/?rev=284&view=rev
Author:   tiran
Date:     2007-04-18 14:43:14 -0700 (Wed, 18 Apr 2007)

Log Message:
-----------
Added encrypted stream class

Added Paths:
-----------
    pymoul/trunk/src/moul/crypt/stream.py

Added: pymoul/trunk/src/moul/crypt/stream.py
===================================================================
--- pymoul/trunk/src/moul/crypt/stream.py	                        (rev 0)
+++ pymoul/trunk/src/moul/crypt/stream.py	2007-04-18 21:43:14 UTC (rev 284)
@@ -0,0 +1,72 @@
+# pyMoul - Python interface to Myst Online URU Live
+# Copyright (C) 2007 Christian Heimes <christian (at) cheimes (dot) de>
+
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the
+# Free Software Foundation; either version 2 of the License, or (at your
+# option) any later version.
+# 
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc., 59
+# Temple Place, Suite 330, Boston, MA 02111-1307 USA
+#
+"""Encrypted file stream
+"""
+__author__ = "Christian Heimes"
+__version__ = "$Id: elf.py 275 2007-03-21 12:39:25Z tiran $"
+__revision__ = "$Revision: 275 $"
+
+import os
+
+from moul.crypt.binary import BinaryFile
+
+class HeaderError(ValueError):
+    pass
+
+class EncryptedStream(object):
+    """Encrypted stream
+    """
+    magic = 12 * '\x00'
+    cipherClass = None
+    blockSize = 1024
+
+    def __init__(self, fdname, key, **kwargs):
+        if isinstane(fdname, basestring):
+            fd = BinaryFile(fdname)
+        elif isinstance(fdname, BinaryFile):
+            fd = fdname
+        else:
+            raise TypeError(fdname)
+        header = fd.read(12)
+        if header != self.magic:
+            HeaderError(header)
+        self._size = fd.read32()
+        fd.seek(0, 2)
+        fsize = fd.tell()
+        fd.seek(16)
+        if fsize-16 < self._size:
+            raise ValueError("Size mismatch %i/%i" % (fsize, self._size))
+        self._cipher = self.cipherClass(key, **kwargs)
+        self._fd = fd
+
+    def read(self):
+        fd.seek(16)
+        remain = self._size
+        bs = self.blockSize
+        fd = self._fd
+        decrypt = self._cipher.decrypt
+        buf = []
+        while True:
+            if remain == 0:
+                break
+            if remain < bs:
+                bs = remain
+            data = fd.read(bs)
+            buf.append(decrypt(data))
+        return ''.join(buf)
+


Property changes on: pymoul/trunk/src/moul/crypt/stream.py
___________________________________________________________________
Name: svn:keywords
   + 'Id Revision'
Name: svn:eol-style
   + native


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