ctypescrypto/ec.py

   1 """
   2 Support for EC keypair operation missing form public libcrypto API
   3 """
   4 from ctypescrypto.pkey import PKey, PKeyError
   5 from ctypes import c_void_p, c_char_p, c_int, byref, POINTER
   6 from ctypescrypto import libcrypto
   7
   8 __all__ = ['create']
   9
  10 def create(curve, data):
  11     """
  12     Creates EC keypair from the just secret key and curve name
  13
  14     @param curve - name of elliptic curve
  15     @param num - byte array or long number representing key
  16     """
  17     ec_key = libcrypto.EC_KEY_new_by_curve_name(curve.nid)
  18     if ec_key is None:
  19         raise PKeyError("EC_KEY_new_by_curvename")
  20     group = libcrypto.EC_KEY_get0_group(ec_key)
  21     if group is None:
  22         raise PKeyError("EC_KEY_get0_group")
  23     libcrypto.EC_GROUP_set_asn1_flag(group, 1)
  24     raw_key = libcrypto.BN_new()
  25     if isinstance(data, int):
  26         libcrypto.BN_hex2bn(byref(raw_key), hex(data))
  27     else:
  28         if raw_key is None:
  29             raise PKeyError("BN_new")
  30         if libcrypto.BN_bin2bn(data, len(data), raw_key) is None:
  31             raise PKeyError("BN_bin2bn")
  32     ctx = libcrypto.BN_CTX_new()
  33     if ctx is None:
  34         raise PKeyError("BN_CTX_new")
  35     order = libcrypto.BN_new()
  36     if order is None:
  37         raise PKeyError("BN_new")
  38     priv_key = libcrypto.BN_new()
  39     if priv_key is None:
  40         raise PKeyError("BN_new")
  41     if libcrypto.EC_GROUP_get_order(group, order, ctx) <= 0:
  42         raise PKeyError("EC_GROUP_get_order")
  43     if libcrypto.BN_nnmod(priv_key, raw_key, order, ctx) <= 0:
  44         raise PKeyError("BN_nnmod")
  45     if libcrypto.EC_KEY_set_private_key(ec_key, priv_key) <= 0:
  46         raise PKeyError("EC_KEY_set_private_key")
  47     pub_key = libcrypto.EC_POINT_new(group)
  48     if pub_key is None:
  49         raise PKeyError("EC_POINT_new")
  50     if libcrypto.EC_POINT_mul(group, pub_key, priv_key, None, None, ctx) <= 0:
  51         raise PKeyError("EC_POINT_mul")
  52     if libcrypto.EC_KEY_set_public_key(ec_key, pub_key) <= 0:
  53         raise PKeyError("EC_KEY_set_public_key")
  54     libcrypto.BN_free(raw_key)
  55     libcrypto.BN_free(order)
  56     libcrypto.BN_free(priv_key)
  57     libcrypto.BN_CTX_free(ctx)
  58     pkey = libcrypto.EVP_PKEY_new()
  59     if pkey is None:
  60         raise PKeyError("EVP_PKEY_new")
  61     if libcrypto.EVP_PKEY_set1_EC_KEY(pkey, ec_key) <= 0:
  62         raise PKeyError("EVP_PKEY_set1_EC_KEY")
  63     libcrypto.EC_KEY_free(ec_key)
  64     return PKey(ptr=pkey, cansign=True)
  65
  66 libcrypto.EVP_PKEY_new.restype = c_void_p
  67 libcrypto.EC_KEY_new_by_curve_name.restype = c_void_p
  68 libcrypto.EC_KEY_new_by_curve_name.argtypes = (c_int,)
  69 libcrypto.BN_new.restype = c_void_p
  70 libcrypto.BN_free.argtypes = (c_void_p, )
  71 libcrypto.BN_hex2bn.argtypes = (POINTER(c_void_p), c_char_p)
  72 libcrypto.BN_bin2bn.argtypes = ( c_char_p, c_int, c_void_p)
  73 libcrypto.BN_bin2bn.restype = c_void_p
  74 libcrypto.BN_CTX_new.restype = c_void_p
  75 libcrypto.BN_CTX_free.argtypes = (c_void_p, )
  76 libcrypto.BN_bin2bn.argtypes = (c_char_p, c_int, c_void_p)
  77 libcrypto.BN_nnmod.restype = c_int
  78 libcrypto.BN_nnmod.argtypes = (c_void_p, c_void_p, c_void_p, c_void_p)
  79 libcrypto.EC_KEY_set_private_key.argtypes = (c_void_p, c_void_p)
  80 libcrypto.EC_POINT_new.argtypes = (c_void_p, )
  81 libcrypto.EC_POINT_new.restype = c_void_p
  82 libcrypto.EC_POINT_mul.argtypes = (c_void_p, c_void_p, c_void_p, c_void_p,
  83                                    c_void_p, c_void_p)
  84 libcrypto.EC_KEY_set_public_key.argtypes = (c_void_p, c_void_p)
  85 libcrypto.EC_KEY_get0_group.restype = c_void_p
  86 libcrypto.EC_KEY_get0_group.argtypes = (c_void_p,)
  87 libcrypto.EC_KEY_free.argtypes=(c_void_p,)
  88 libcrypto.EVP_PKEY_set1_EC_KEY.argtypes = (c_void_p, c_void_p)
  89 libcrypto.EC_GROUP_set_asn1_flag.argtypes = (c_void_p, c_int)
  90 libcrypto.EC_GROUP_get_order.restype = c_int
  91 libcrypto.EC_GROUP_get_order.argtypes = (c_void_p, c_void_p, c_void_p)