HOARD datafile decryptor

from __future__ import print_function
import sys, os

def getEncryptionKey(filename):
    # code to generate substitute key
    #key1 = "lHqyhFGALH5Rv6yNpwvmEcrrK0GiUaevmSs14EVCgvDFntDKWSIn8kHegKeT"
    #key2 = "SjQIOGLW7HEhZm3r3mXilisiv3o1vPaQzMco4hxBSGCjw8D1eC8y9rvZQmXx"
    #key = ""

    #for index in range(0, 60):
    #   ck1 = ord(key1[index]) if index%3 is not 1 else 0
    #   ck2 = ord(key2[index]) if index%3 is not 0 else 0
    #   key += chr(ck1 ^ ck2)

    #print(repr(key))

    if len(filename) > 60:
        print("Filename '{0}' too long".format(filename), file=sys.stderr)
        return None

    # \x6c\x6a\x20\x79\x4f\x01\x47\x57\x7b\x48\x45\x3a\x76\x6d\x4a\x4e\x33\x1a\x76\x69\x29\x63\x73\x1b\x4b
    # \x33\x28\x69\x76\x31\x65\x51\x17\x53\x63\x5e\x34\x68\x2e\x43\x53\x31\x44\x6a\x19\x74\x44\x7a\x57\x43
    # \x71\x6e\x39\x19\x48\x5a\x36\x4b\x58\x2c
    staticKey = bytearray(b"lj yO\x01GW{HE:vmJN3\x1avi)cs\x1bK3(iv1eQ\x17Sc^4h.CS1Dj\x19tDzWCqn9\x19HZ6KX,")
    filename = bytearray(filename.replace("\\", "/"), "utf-8")

    return bytearray([filename[i] ^ staticKey[i] for i in range(0, len(filename))])

def getSteamGameDir(appId):
    import _winreg as winreg

    regkeys = [(winreg.HKEY_LOCAL_MACHINE, r"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Steam App {0}"),
               (winreg.HKEY_LOCAL_MACHINE, r"SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\Steam App {0}")]

    path = None

    for regkey in regkeys:
        try:
            hKey = winreg.OpenKey(regkey[0], regkey[1].format(appId))
            path = winreg.QueryValueEx(hKey, "InstallLocation")[0]
            print("Found game directory in HKLM\\{0}: {1}".format(regkey[1].format(appId), path), file=sys.stderr)
            hKey.Close()
            break
        except WindowsError as e:
            continue

    if path is None:
        print("Couldn't find the game path in the registry", file=sys.stderr)
        return None

    return path

# performance results:
# unbuffered read(1)s: 6.9s
# buffered reads with fixed size: 3.8s
# buffered reads with a multiple of keyLen: 2.1s
# (the additional counter variable seems to cost a lot)
def decryptFile(src, dest, key):
    with open(src, 'rb') as srcFile:
        with open(dest, 'wb') as destFile:
            keyLen = len(key)
            i = 0
            read = bytearray(srcFile.read(4096*keyLen))
            readLen = len(read)
            write = bytearray()
            while readLen is not 0:
                while i < readLen:
                    write.append(read[i]^key[i%keyLen])
                    i += 1
                i = 0
                destFile.write(write)
                read = bytearray(srcFile.read(4096*keyLen))
                readLen = len(read)
                write = bytearray()


if __name__ == "__main__":
    path = getSteamGameDir(63000)
    if not path:
        print("Could not find game directory, aborting...", file=sys.stderr)
        sys.exit(-1)
    encryptedDataPath = os.path.join(path, "encrypteddata")
    dataPath = os.path.join(path, "data")
    files = 0
    skipped = 0
    import time
    timestart = time.time()
    for dir in os.walk(encryptedDataPath):
        for file in dir[2]:
            relPath = os.path.join(dir[0][len(encryptedDataPath)+1:], file)
            destDir = os.path.join(dataPath, dir[0][len(encryptedDataPath)+1:])
            destPath = os.path.join(destDir, file)
            if os.path.exists(destPath):
                print("Skipping existing file {0}".format(relPath), file=sys.stderr)
                skipped += 1
                continue
            print("Decrypting {0}...".format(relPath), file=sys.stderr, end='')
            if not os.path.exists(destDir):
                os.makedirs(destDir)
            decryptFile(os.path.join(dir[0], file),
                        destPath,
                        getEncryptionKey(relPath))
            print(" done", file=sys.stderr)
            files += 1
    print("Done. Decrypted {0} files ({1} skipped).".format(files, skipped), file=sys.stderr)
    print("Took {0}.".format(time.time()-timestart), file=sys.stderr)