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secp256k1 extmod: minor cleanups, add private key check

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The MMGen Project 2023-12-12 10:19:52 +00:00
commit 5025ed9dc3
Signed by: mmgen
GPG key ID: 3F8B1861E32B7DA2
1 changed files with 33 additions and 17 deletions
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50
extmod/secp256k1mod.c
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@ -20,40 +20,56 @@
#include <Python.h>
#include <secp256k1.h>
int privkey_check(
const secp256k1_context * ctx,
const unsigned char * privkey_bytes,
const Py_ssize_t privkey_bytes_len,
const char * desc
) {
if (privkey_bytes_len != 32) {
char buf[64 + strlen(desc)];
sprintf(buf, "%s length not 32 bytes", desc);
PyErr_SetString(PyExc_ValueError, buf);
return 0;
}
if (secp256k1_ec_seckey_verify(ctx, privkey_bytes) != 1) {
char buf[64 + strlen(desc)];
sprintf(buf, "%s not in allowable range", desc);
PyErr_SetString(PyExc_ValueError, buf);
return 0;
}
return 1;
}
static PyObject * pubkey_gen(PyObject *self, PyObject *args) {
const unsigned char * privkey;
const int klen;
const unsigned char * privkey_bytes;
const Py_ssize_t privkey_bytes_len;
const int compressed;
if (!PyArg_ParseTuple(args, "y#I", &privkey, &klen, &compressed)) {
if (!PyArg_ParseTuple(args, "y#I", &privkey_bytes, &privkey_bytes_len, &compressed)) {
PyErr_SetString(PyExc_ValueError, "Unable to parse extension mod arguments");
return NULL;
}
if (klen != 32) {
PyErr_SetString(PyExc_ValueError, "Private key length not 32 bytes");
return NULL;
}
size_t pubkey_bytes_len = compressed == 1 ? 33 : 65;
unsigned char pubkey_bytes[pubkey_bytes_len];
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);
}
secp256k1_context *ctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
if (ctx == NULL) {
PyErr_SetString(PyExc_RuntimeError, "Context initialization failed");
return NULL;
}
if (secp256k1_ec_pubkey_create(ctx, &pubkey, privkey) != 1) {
if (!privkey_check(ctx, privkey_bytes, privkey_bytes_len, "Private key")) {
return NULL;
}
if (secp256k1_ec_pubkey_create(ctx, &pubkey, privkey_bytes) != 1) {
PyErr_SetString(PyExc_RuntimeError, "Public key creation failed");
return NULL;
}
if (secp256k1_ec_pubkey_serialize(ctx, pubkeyc, &pubkeyclen, &pubkey,
if (secp256k1_ec_pubkey_serialize(ctx, pubkey_bytes, &pubkey_bytes_len, &pubkey,
compressed == 1 ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED) != 1) {
PyErr_SetString(PyExc_RuntimeError, "Public key serialization failed");
return NULL;
}
return Py_BuildValue("y#", pubkeyc,pubkeyclen);
return Py_BuildValue("y#", pubkey_bytes, pubkey_bytes_len);
}
/* https://docs.python.org/3/howto/cporting.html */