Python OpenSSL.EC_POINT_set_compressed_coordinates_GFp Examples

Example #1

def get_pos_y_for_x(pubkey_x, yneg=0):
    key = pub_key = pub_key_x = pub_key_y = None
    try:
        key = OpenSSL.EC_KEY_new_by_curve_name(OpenSSL.get_curve('secp256k1'))
        group = OpenSSL.EC_KEY_get0_group(key)
        pub_key_x = OpenSSL.BN_bin2bn(pubkey_x, len(pubkey_x), 0)
        pub_key = OpenSSL.EC_POINT_new(group)

        if OpenSSL.EC_POINT_set_compressed_coordinates_GFp(group, pub_key,
                                                           pub_key_x, yneg, 0) == 0:
            raise Exception("[OpenSSL] EC_POINT_set_compressed_coordinates_GFp FAIL ... " + OpenSSL.get_error())


        pub_key_y = OpenSSL.BN_new()
        if (OpenSSL.EC_POINT_get_affine_coordinates_GFp(group, pub_key,
                                                        pub_key_x,
                                                        pub_key_y, 0
                                                       )) == 0:
            raise Exception("[OpenSSL] EC_POINT_get_affine_coordinates_GFp FAIL ... " + OpenSSL.get_error())

        pubkeyy = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(pub_key_y))
        OpenSSL.BN_bn2bin(pub_key_y, pubkeyy)
        pubkeyy = pubkeyy.raw
        field_size = OpenSSL.EC_GROUP_get_degree(OpenSSL.EC_KEY_get0_group(key))
        secret_len = int((field_size + 7) / 8)
        if len(pubkeyy) < secret_len:
            pubkeyy = pubkeyy.rjust(secret_len, b'\0')
        return pubkeyy
    finally:
        if key is not None: OpenSSL.EC_KEY_free(key)
        if pub_key is not None: OpenSSL.EC_POINT_free(pub_key)
        if pub_key_x is not None: OpenSSL.BN_free(pub_key_x)
        if pub_key_y is not None: OpenSSL.BN_free(pub_key_y)