How to perform UDS session unlock using security dll from python program?

I want to automate some WDBI services which requires security unlock. I have a dll which can be invoked from CANoe, but I don't want to use canoe hardware also I don't know the function calls in the dll. Is there any way that I can invoke dll from python program to perform session unlock?

Solution

With the DLL at hand you could use a tool like DependencyWalker to see the exported symbols of the DLL. But if you already know that your DLL works in CANoe, it will follow the APIs specified by Vector Informatik to be implemented in an Security Access DLL for CANoe: GenerateKeyEx & GenerateKeyExOpt.

GenerateKeyEx:

int VKeyGenResult ExGenerateKeyEx (
  const unsigned char* ipSeedArray,
  unsigned int iSeedArraySize,
  const unsigned int iSecurityLevel,
  const char* ipVariant,
  unsigned char* iopKeyArray,
  unsigned int iMaxKeyArraySize,
  unsigned int& oActualKeyArraySize );

GenerateKeyExOpt:

VKeyGenResult ExOptGenerateKeyExOpt (
  const unsigned char* ipSeedArray,
  unsigned int iSeedArraySize,
  const unsigned int iSecurityLevel,
  const char* ipVariant,
  const char* ipOptions,
  unsigned char* iopKeyArray,
  unsigned int iMaxKeyArraySize,
  unsigned int& oActualKeyArraySize );

Then it is just a matter of calling to this Dll from python, i.e. using ctypes.

import ctypes

mylib = ctypes.WinDLL("./GenerateKeyExImpl.dll")
seed = (ctypes.c_byte * 4)(0xff, 0xfe, 0xfd, 0xfc) # these bytes you should get from the ECU i.e.
# Tx 27 01
# Rx 67 01 ff fe fd fc
key = (ctypes.c_byte * 4)() # this will contain the secret key after Dll call
keylength = ctypes.c_int(4) # this will contain the secret key length after Dll call
mylib.ExGenerateKeyEx(
     ctypes.pointer(seed), # Seed from the ECU
     ctypes.c_int(4), # Example: Seed length = 4 bytes
     ctypes.c_int(1), # Example: Security Level 1
     POINTER(c_int)(), # Example: NULL = No variant string
     ctypes.pointer(key), # Key to send back to the ECU
     ctypes.c_int(4), # Example: Key Max length = 4 bytes
     ctypes.pointer(keylength), # Example: Seed length = 4 bytes
)
# TODO: Send "key" back to the ECU i.e.
# Tx 27 02 XX XX XX XX
# Rx 67 02