Using DPAPI with Python?

Question

Is there a way to use the DPAPI (Data Protection Application Programming Interface) on Windows XP with Python?

I would prefer to use an existing module if there is one that can do it. Unfortunately I haven't been able to find a way with Google or Stack Overflow.

EDIT: I've taken the example code pointed to by "dF" and tweaked it into a standalone library which can be simply used at a high level to crypt and decrypt using DPAPI in user mode. Simply call dpapi.cryptData(text_to_encrypt) which returns an encrypted string, or the reverse decryptData(encrypted_data_string), which returns the plain text. Here's the library:

# DPAPI access library
# This file uses code originally created by Crusher Joe:
# http://article.gmane.org/gmane.comp.python.ctypes/420
#

from ctypes import *
from ctypes.wintypes import DWORD

LocalFree = windll.kernel32.LocalFree
memcpy = cdll.msvcrt.memcpy
CryptProtectData = windll.crypt32.CryptProtectData
CryptUnprotectData = windll.crypt32.CryptUnprotectData
CRYPTPROTECT_UI_FORBIDDEN = 0x01
extraEntropy = "cl;ad13 \0al;323kjd #(adl;k$#ajsd"

class DATA_BLOB(Structure):
    _fields_ = [("cbData", DWORD), ("pbData", POINTER(c_char))]

def getData(blobOut):
    cbData = int(blobOut.cbData)
    pbData = blobOut.pbData
    buffer = c_buffer(cbData)
    memcpy(buffer, pbData, cbData)
    LocalFree(pbData);
    return buffer.raw

def Win32CryptProtectData(plainText, entropy):
    bufferIn = c_buffer(plainText, len(plainText))
    blobIn = DATA_BLOB(len(plainText), bufferIn)
    bufferEntropy = c_buffer(entropy, len(entropy))
    blobEntropy = DATA_BLOB(len(entropy), bufferEntropy)
    blobOut = DATA_BLOB()

    if CryptProtectData(byref(blobIn), u"python_data", byref(blobEntropy),
                       None, None, CRYPTPROTECT_UI_FORBIDDEN, byref(blobOut)):
        return getData(blobOut)
    else:
        return ""

def Win32CryptUnprotectData(cipherText, entropy):
    bufferIn = c_buffer(cipherText, len(cipherText))
    blobIn = DATA_BLOB(len(cipherText), bufferIn)
    bufferEntropy = c_buffer(entropy, len(entropy))
    blobEntropy = DATA_BLOB(len(entropy), bufferEntropy)
    blobOut = DATA_BLOB()
    if CryptUnprotectData(byref(blobIn), None, byref(blobEntropy), None, None,
                              CRYPTPROTECT_UI_FORBIDDEN, byref(blobOut)):
        return getData(blobOut)
    else:
        return ""

def cryptData(text):
    return Win32CryptProtectData(text, extraEntropy)

def decryptData(cipher_text):
    return Win32CryptUnprotectData(cipher_text, extraEntropy)

Answer 1

The easiest way would be to use Iron Python.

Answer 2

I have been using CryptProtectData and CryptUnprotectData through ctypes, with the code from

http://article.gmane.org/gmane.comp.python.ctypes/420

and it has been working well.

Answer 3

Also, pywin32 implements CryptProtectData and CryptUnprotectData in the win32crypt module.