mmgen-wallet/extmod/secp256k1mod.c

/*
  mmgen = Multi-Mode GENerator, command-line Bitcoin cold storage solution
  Copyright (C)2013-2018 The MMGen Project <mmgen@tuta.io>

  This program is free software: you can redistribute it and/or modify it under
  the terms of the GNU General Public License as published by the Free Software
  Foundation, either version 3 of the License, or (at your option) any later
  version.

  This program is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  details.

  You should have received a copy of the GNU General Public License along with
  this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <Python.h>
#include <secp256k1.h>

static PyObject * priv2pub(PyObject *self, PyObject *args) {
	const unsigned char * privkey;
	const int klen;
	const int compressed;
	if (!PyArg_ParseTuple(args, "t#I", &privkey, &klen, &compressed))
		return NULL;
	if (klen != 32) {
		PyErr_SetString(PyExc_ValueError, "Private key length not 32 bytes");
		return NULL;
	}
	secp256k1_pubkey pubkey;
	size_t pubkeyclen = compressed == 1 ? 33: 65;
	unsigned char pubkeyc[pubkeyclen];
	static secp256k1_context *ctx = NULL;
	if (ctx == NULL) {
	/*	puts ("Initializing context"); */
		ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY);
	}
	if (secp256k1_ec_pubkey_create(ctx, &pubkey, privkey) != 1) {
		PyErr_SetString(PyExc_RuntimeError, "Public key creation failed");
		return NULL;
	}
	if (secp256k1_ec_pubkey_serialize(ctx, pubkeyc, &pubkeyclen, &pubkey,
			compressed == 1 ? SECP256K1_EC_COMPRESSED: SECP256K1_EC_UNCOMPRESSED) != 1) {
		PyErr_SetString(PyExc_RuntimeError, "Public key serialization failed");
		return NULL;
	}
	return Py_BuildValue("s#", pubkeyc,pubkeyclen);
}

static PyMethodDef secp256k1Methods[] = {
	{"priv2pub", priv2pub, METH_VARARGS, "Generate pubkey from privkey using libsecp256k1"},
	{NULL, NULL, 0, NULL} /* Sentinel */
};

PyMODINIT_FUNC initsecp256k1(void) {
	PyObject *m;
	m = Py_InitModule("secp256k1", secp256k1Methods);
	if (m == NULL) return;
}