from System import Int32, Byte, IntPtr
import System
from System.IO import *
from System.Runtime.InteropServices import Marshal
from ctypes import *
import sys

mscoree = windll.mscoree

def GetLastStrongNameError():
    error = Marshal.GetExceptionForHR(mscoree.StrongNameErrorInfo())
    return error.Message

def GenerateKeyPair (keyK):
    if keyK < 0 or keyK > 2 :
        raise System.ArgumentOutOfRangeException(
        "keyK", keyK, "Invalid Key Size -- should be 1 or 2")

    # variables that hold the unmanaged key
    keyBlob = c_void_p()
    generatedSize = c_uint(0)

    # create the key
    createdKey = mscoree.StrongNameKeyGenEx(
                                   None,
                                   c_uint(0),
                                   c_uint(1024 * keyK),
                                   byref(keyBlob),
                                   byref(generatedSize))

    try:
       # if there was a problem, translate it and report it
       if not createdKey or keyBlob.value == 0:
           raise  System.InvalidOperationException(GetLastStrongNameError())

       #make sure the key size makes sense
       generatedSize = generatedSize.value
       if generatedSize <= 0 or generatedSize > Int32.MaxValue:
           raise System.InvalidOperationException("InternalError")

       # get the key into managed memory
       key = System.Array.CreateInstance(Byte, generatedSize)
       Marshal.Copy(IntPtr(keyBlob.value), key, 0, generatedSize)
       return key
    finally:
       # release the unmanaged memory the key resides in
       if keyBlob.value != 0:
           mscoree.StrongNameFreeBuffer(keyBlob)

# write the key to the specified file if it is not already present
keypath = sys.argv[1]
if not (File.Exists(keypath)):
    print 'Generating key at %s' % (keypath)
    key = GenerateKeyPair (1)
    # should do this using a 'with'
    snkStream = FileStream(keypath, FileMode.Create, FileAccess.Write)
    snkWriter = BinaryWriter(snkStream)
    snkWriter.Write(key)
    snkWriter.Close()