# -*- Mode: Python -*-

# OpenSSL wrapper

import ctypes
import ctypes.util

ssl = ctypes.cdll.LoadLibrary (ctypes.util.find_library ('ssl') or 'libeay32')

# this specifies the curve used with ECDSA.
NID_secp256k1 = 714 # from openssl/obj_mac.h

# Thx to Sam Devlin for the ctypes magic 64-bit fix.
def check_result (val, func, args):
    if val == 0:
        raise ValueError
    else:
        return ctypes.c_void_p (val)

ssl.EC_KEY_new_by_curve_name.restype = ctypes.c_void_p
ssl.EC_KEY_new_by_curve_name.errcheck = check_result

class KEY:

    def __init__(self):
        self.POINT_CONVERSION_COMPRESSED = 2
        self.POINT_CONVERSION_UNCOMPRESSED = 4
        self.k = ssl.EC_KEY_new_by_curve_name(NID_secp256k1)

    def __del__(self):
        if ssl:
            ssl.EC_KEY_free(self.k)
        self.k = None

    def generate(self, secret=None):
        if secret:
            self.prikey = secret
            priv_key = ssl.BN_bin2bn(secret, 32, ssl.BN_new())
            group = ssl.EC_KEY_get0_group(self.k)
            pub_key = ssl.EC_POINT_new(group)
            ctx = ssl.BN_CTX_new()
            ssl.EC_POINT_mul(group, pub_key, priv_key, None, None, ctx)
            ssl.EC_KEY_set_private_key(self.k, priv_key)
            ssl.EC_KEY_set_public_key(self.k, pub_key)
            ssl.EC_POINT_free(pub_key)
            ssl.BN_CTX_free(ctx)
            return self.k
        else:
            return ssl.EC_KEY_generate_key(self.k)

    def set_privkey(self, key):
        self.mb = ctypes.create_string_buffer(key)
        ssl.d2i_ECPrivateKey(ctypes.byref(self.k), ctypes.byref(ctypes.pointer(self.mb)), len(key))

    def set_pubkey(self, key):
        self.mb = ctypes.create_string_buffer(key)
        ssl.o2i_ECPublicKey(ctypes.byref(self.k), ctypes.byref(ctypes.pointer(self.mb)), len(key))

    def get_privkey(self):
        size = ssl.i2d_ECPrivateKey(self.k, 0)
        mb_pri = ctypes.create_string_buffer(size)
        ssl.i2d_ECPrivateKey(self.k, ctypes.byref(ctypes.pointer(mb_pri)))
        return mb_pri.raw

    def get_pubkey(self):
        size = ssl.i2o_ECPublicKey(self.k, 0)
        mb = ctypes.create_string_buffer(size)
        ssl.i2o_ECPublicKey(self.k, ctypes.byref(ctypes.pointer(mb)))
        return mb.raw

    def sign(self, hash):
        sig_size = ssl.ECDSA_size(self.k)
        mb_sig = ctypes.create_string_buffer(sig_size)
        sig_size0 = ctypes.c_uint32()
        assert 1 == ssl.ECDSA_sign(0, hash, len(hash), mb_sig, ctypes.byref(sig_size0), self.k)
        return mb_sig.raw[:sig_size0.value]

    def verify(self, hash, sig):
        return ssl.ECDSA_verify(0, hash, len(hash), sig, len(sig), self.k)

    def set_compressed(self, compressed):
        if compressed:
            form = self.POINT_CONVERSION_COMPRESSED
        else:
            form = self.POINT_CONVERSION_UNCOMPRESSED
        ssl.EC_KEY_set_conv_form(self.k, form)

    def get_secret(self):
        bn = ssl.EC_KEY_get0_private_key(self.k)
        mb = ctypes.create_string_buffer(32)
        ssl.BN_bn2bin(bn, mb)
        return mb.raw

if __name__ == '__main__':
    # ethalone keys
    ec_secret = '' + \
        'a0dc65ffca799873cbea0ac274015b9526505daaaed385155425f7337704883e'
    ec_private = '308201130201010420' + \
        'a0dc65ffca799873cbea0ac274015b9526505daaaed385155425f7337704883e' + \
        'a081a53081a2020101302c06072a8648ce3d0101022100' + \
        'fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f' + \
        '300604010004010704410479be667ef9dcbbac55a06295ce870b07029bfcdb2d' + \
        'ce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a6' + \
        '8554199c47d08ffb10d4b8022100' + \
        'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141' + \
        '020101a14403420004' + \
        '0791dc70b75aa995213244ad3f4886d74d61ccd3ef658243fcad14c9ccee2b0a' + \
        'a762fbc6ac0921b8f17025bb8458b92794ae87a133894d70d7995fc0b6b5ab90'

    k = KEY()
    k.generate (ec_secret.decode('hex'))
    k.set_compressed(True)
    print k.get_privkey ().encode('hex')
    print k.get_pubkey().encode('hex')
    print k.get_secret().encode('hex')