ctypescrypto/engine.py

   1 """
   2 engine loading and configuration
   3 """
   4 from ctypes import c_void_p, c_char_p, c_int
   5 from ctypescrypto import libcrypto
   6 from ctypescrypto.exception import LibCryptoError
   7
   8 __all__ = ['default', 'set_default', 'Engine']
   9
  10 default = None
  11
  12 class Engine(object):
  13     """
  14     Represents Openssl loadable module (engine).
  15     Allows to create PKey objects from private keys stored
  16     in the token, accessed by engine
  17     """
  18     def __init__(self, engine_id, **kwargs):
  19         eng = libcrypto.ENGINE_by_id(engine_id)
  20         if eng is None:
  21             # Try load engine
  22             eng = libcrypto.ENGINE_by_id("dynamic")
  23             if  eng is None:
  24                 raise LibCryptoError("Cannot get 'dynamic' engine")
  25             if not libcrypto.ENGINE_ctrl_cmd_string(eng, "SO_PATH",
  26                                                     engine_id, 0):
  27                 raise LibCryptoError("Cannot execute ctrl cmd SO_PATH")
  28             if not libcrypto.ENGINE_ctrl_cmd_string(eng, "LOAD", None, 0):
  29                 raise LibCryptoError("Cannot execute ctrl cmd LOAD")
  30         if eng is None:
  31             raise ValueError("Cannot find engine " + engine)
  32         for cmd, value in kwargs.items():
  33             if not libcrypto.ENGINE_ctrl_cmd_string(eng, cmd, value, 0):
  34                 raise LibCryptoError("Cannot execute ctrl cmd %s" % cmd)
  35         if not libcrypto.ENGINE_init(eng):
  36             raise LibCryptoError("Cannot initialize engine")
  37         self.ptr = eng
  38
  39     def private_key(self, key_id, ui_method = None, ui_data=None):
  40         from ctypescrypto.pkey import PKey
  41         if ui_method is None:
  42             ui_ptr = libcrypto.UI_OpenSSL()
  43         else:
  44             ui_ptr = ui_method.ptr
  45         pkey = libcrypto.ENGINE_load_private_key(self.ptr, key_id, ui_ptr,
  46                                                  ui_data)
  47         if pkey is None:
  48             raise LibCryptoError("Cannot load private key")
  49         return PKey(ptr=pkey, cansign=True)
  50
  51 def set_default(eng, algorithms=0xFFFF):
  52     """
  53     Sets specified engine  as default for all
  54     algorithms, supported by it
  55
  56     For compatibility with 0.2.x if string is passed instead
  57     of engine, attempts to load engine with this id
  58     """
  59     if not isinstance(eng,Engine):
  60         eng=Engine(eng)
  61     global default
  62     libcrypto.ENGINE_set_default(eng.ptr, c_int(algorithms))
  63     default = eng
  64
  65 # Declare function result and arguments for used functions
  66 libcrypto.ENGINE_by_id.restype = c_void_p
  67 libcrypto.ENGINE_by_id.argtypes = (c_char_p, )
  68 libcrypto.ENGINE_set_default.argtypes = (c_void_p, c_int)
  69 libcrypto.ENGINE_ctrl_cmd_string.argtypes = (c_void_p, c_char_p, c_char_p,
  70                                              c_int)
  71 libcrypto.ENGINE_finish.argtypes = (c_char_p, )
  72 libcrypto.ENGINE_init.argtypes = (c_void_p, )
  73 libcrypto.UI_OpenSSL.restype = c_void_p
  74 libcrypto.ENGINE_load_private_key.argtypes = (c_void_p, c_char_p, c_void_p, c_void_p)
  75 libcrypto.ENGINE_load_private_key.restype = c_void_p