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
   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=libcrypto.EC_KEY_new_by_curve_name(curve.nid)
  18         if ec is None:
  19                 raise PKeyError("EC_KEY_new_by_curvename")
  20         group=libcrypto.EC_KEY_get0_group(ec)
  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                 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,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,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         p=libcrypto.EVP_PKEY_new()
  59         if p is None:
  60                 raise PKeyError("EVP_PKEY_new")
  61         if libcrypto.EVP_PKEY_set1_EC_KEY(p,ec)<=0:
  62                 raise PKeyError("EVP_PKEY_set1_EC_KEY")
  63         libcrypto.EC_KEY_free(ec)
  64         return PKey(ptr=p,cansign=True)
  65
  66
  67 libcrypto.EVP_PKEY_new.restype=c_void_p
  68 libcrypto.BN_new.restype=c_void_p
  69 libcrypto.BN_free.argtypes=(c_void_p,)
  70 libcrypto.BN_CTX_new.restype=c_void_p
  71 libcrypto.BN_CTX_free.argtypes=(c_void_p,)
  72 libcrypto.BN_bin2bn.argtypes=(c_char_p,c_int,c_void_p)
  73 libcrypto.EC_KEY_set_private_key.argtypes=(c_void_p,c_void_p)
  74 libcrypto.EC_POINT_new.argtypes=(c_void_p,)
  75 libcrypto.EC_POINT_new.restype=c_void_p
  76 libcrypto.EC_POINT_mul.argtypes=(c_void_p,c_void_p,c_void_p,c_void_p,c_void_p,c_void_p)
  77 libcrypto.EC_KEY_set_public_key.argtypes=(c_void_p,c_void_p)
  78
  79