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