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 def create(curve,data):
   9         """
  10                 Creates EC keypair from the just secret key and curve name
  11
  12                 @param curve - name of elliptic curve
  13                 @param num - long number representing key
  14         """
  15         ec=libcrypto.EC_KEY_new_by_curve_name(curve.nid)
  16         if ec is None:
  17                 raise PKeyError("EC_KEY_new_by_curvename")
  18         group=libcrypto.EC_KEY_get0_group(ec)
  19         if group is None:
  20                 raise PKeyError("EC_KEY_get0_group")
  21         libcrypto.EC_GROUP_set_asn1_flag(group,1)
  22         raw_key=libcrypto.BN_new()
  23         if raw_key is None:
  24                 raise PKeyError("BN_new")
  25         ctx=libcrypto.BN_CTX_new()
  26         if ctx is None:
  27                 raise PKeyError("BN_CTX_new")
  28         if libcrypto.BN_bin2bn(data,len(data),raw_key) is None:
  29                 raise PKeyError("BN_bin2bn")
  30         order=libcrypto.BN_new()
  31         if order is None:
  32                 raise PKeyError("BN_new")
  33         priv_key = libcrypto.BN_new()
  34         if priv_key is None:
  35                 raise PKeyError("BN_new")
  36         if libcrypto.EC_GROUP_get_order(group,order,ctx) <=0:
  37                 raise PKeyError("EC_GROUP_get_order")
  38         if libcrypto.BN_nnmod(priv_key,raw_key,order,ctx) <=0:
  39                 raise PKeyError("BN_nnmod")
  40         if libcrypto.EC_KEY_set_private_key(ec,priv_key)<=0:
  41                 raise PKeyError("EC_KEY_set_private_key")
  42         pub_key=libcrypto.EC_POINT_new(group)
  43         if pub_key is None:
  44                 raise PKeyError("EC_POINT_new")
  45         if libcrypto.EC_POINT_mul(group,pub_key,priv_key,None,None,ctx)<=0:
  46                 raise PKeyError("EC_POINT_mul")
  47         if libcrypto.EC_KEY_set_public_key(ec,pub_key)<=0:
  48                 raise PKeyError("EC_KEY_set_public_key")
  49         libcrypto.BN_free(raw_key)
  50         libcrypto.BN_free(order)
  51         libcrypto.BN_free(priv_key)
  52         libcrypto.BN_CTX_free(ctx)
  53         p=libcrypto.EVP_PKEY_new()
  54         if p is None:
  55                 raise PKeyError("EVP_PKEY_new")
  56         if libcrypto.EVP_PKEY_set1_EC_KEY(p,ec)<=0:
  57                 raise PKeyError("EVP_PKEY_set1_EC_KEY")
  58         libcrypto.EC_KEY_free(ec)
  59         return PKey(ptr=p,cansign=True)
  60
  61
  62 libcrypto.EVP_PKEY_new.restype=c_void_p
  63 libcrypto.BN_new.restype=c_void_p
  64 libcrypto.BN_free.argtypes=(c_void_p,)
  65 libcrypto.BN_CTX_new.restype=c_void_p
  66 libcrypto.BN_CTX_free.argtypes=(c_void_p,)
  67 libcrypto.BN_bin2bn.argtypes=(c_char_p,c_int,c_void_p)
  68 libcrypto.EC_KEY_set_private_key.argtypes=(c_void_p,c_void_p)
  69 libcrypto.EC_POINT_new.argtypes=(c_void_p,)
  70 libcrypto.EC_POINT_new.restype=c_void_p
  71 libcrypto.EC_POINT_mul.argtypes=(c_void_p,c_void_p,c_void_p,c_void_p,c_void_p,c_void_p)
  72 libcrypto.EC_KEY_set_public_key.argtypes=(c_void_p,c_void_p)
  73
  74