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xxtea.c
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xxtea.c
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/*
* Copyright (c) 2014-2020, Yue Du
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <Python.h>
#include <ctype.h>
#include <stdio.h>
#define VERSION "3.3.0"
#if PY_MAJOR_VERSION >= 3
#define PyString_FromStringAndSize PyBytes_FromStringAndSize
#define PyString_AS_STRING PyBytes_AsString
#endif
#if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_SIZE)
#if defined(_MSC_VER) && !defined(inline)
#define inline __inline /* required for py2.x support on windows */
#endif
static inline void _Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size)
{ ob->ob_size = size; }
#define Py_SET_SIZE(ob, size) _Py_SET_SIZE((PyVarObject*)(ob), size)
#endif
#define XFREE(o) do { if ((o) == NULL) ; else free(o); } while (0)
#define DELTA 0x9e3779b9
#define MX (((z>>5^y<<2) + (y>>3^z<<4)) ^ ((sum^y) + (key[(p&3)^e] ^ z)))
static PyObject *module, *binascii;
static void btea(unsigned int *v, int n, unsigned int const key[4], unsigned int rounds)
{
unsigned int y, z, sum;
unsigned p, e;
if (n > 1) { /* Coding Part */
rounds = rounds == 0 ? 6 + 52 / n: rounds;
sum = 0;
z = v[n - 1];
do {
sum += DELTA;
e = (sum >> 2) & 3;
for (p = 0; p < n - 1; p++) {
y = v[p + 1];
z = v[p] += MX;
}
y = v[0];
z = v[n - 1] += MX;
}
while (--rounds);
}
else if (n < -1) { /* Decoding Part */
n = -n;
rounds = rounds == 0 ? 6 + 52 / n: rounds;
sum = rounds * DELTA;
y = v[0];
do {
e = (sum >> 2) & 3;
for (p = n - 1; p > 0; p--) {
z = v[p - 1];
y = v[p] -= MX;
}
z = v[n - 1];
y = v[0] -= MX;
sum -= DELTA;
}
while (--rounds);
}
}
static int bytes2longs(const char *in, int inlen, unsigned int *out, int padding)
{
int i, pad;
const unsigned char *s;
s = (const unsigned char *)in;
/* (i & 3) << 3 -> [0, 8, 16, 24] */
for (i = 0; i < inlen; i++) {
out[i >> 2] |= s[i] << ((i & 3) << 3);
}
/* PKCS#7 padding */
if (padding) {
pad = 4 - (inlen & 3);
/* make sure lenght of out >= 2 */
pad = (inlen < 4) ? pad + 4 : pad;
for (i = inlen; i < inlen + pad; i++) {
out[i >> 2] |= pad << ((i & 3) << 3);
}
}
/* Divided by 4, and then rounded up (ceil) to an integer.
* Which is the number of how many longs we've got.
*/
return ((i - 1) >> 2) + 1;
}
static int longs2bytes(unsigned int *in, int inlen, char *out, int padding)
{
int i, outlen, pad;
unsigned char *s;
s = (unsigned char *)out;
for (i = 0; i < inlen; i++) {
s[4 * i] = in[i] & 0xFF;
s[4 * i + 1] = (in[i] >> 8) & 0xFF;
s[4 * i + 2] = (in[i] >> 16) & 0xFF;
s[4 * i + 3] = (in[i] >> 24) & 0xFF;
}
outlen = inlen * 4;
/* PKCS#7 unpadding */
if (padding) {
pad = s[outlen - 1];
outlen -= pad;
if (pad < 1 || pad > 8) {
/* invalid padding */
return -1;
}
if (outlen < 0) {
return -2;
}
for (i = outlen; i < inlen * 4; i++) {
if (s[i] != pad) {
return -3;
}
}
}
s[outlen] = '\0';
/* How many bytes we've got */
return outlen;
}
/*****************************************************************************
* Module Functions ***********************************************************
****************************************************************************/
static char *keywords[] = {"data", "key", "padding", "rounds", NULL};
PyDoc_STRVAR(
xxtea_encrypt_doc,
"encrypt (data, key, padding=True, rounds=0)\n\n"
"Encrypt `data` with a 16-byte `key`, return binary bytes.");
static PyObject *xxtea_encrypt(PyObject *self, PyObject *args, PyObject *kwargs)
{
int alen, dlen, klen, padding;
PyObject *retval;
char *retbuf;
unsigned int *d, k[4], rounds;
Py_buffer data, key;
d = NULL;
retval = NULL;
k[0] = k[1] = k[2] = k[3] = 0;
padding = 1;
rounds = 0;
data.buf = data.obj = key.buf = key.obj = NULL;
if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s*s*|iI", keywords, &data, &key, &padding, &rounds)) {
return NULL;
}
padding = padding != 0 ? 1 : 0;
dlen = data.len;
klen = key.len;
if (klen != 16) {
PyErr_SetString(PyExc_ValueError, "Need a 16-byte key.");
goto cleanup;
}
if (!padding && (dlen < 8 || (dlen & 3) != 0)) {
PyErr_SetString(PyExc_ValueError, "Data length must be a multiple of 4 bytes and must not be less than 8 bytes");
goto cleanup;
}
alen = dlen < 4 ? 2 : (dlen >> 2) + padding;
d = (unsigned int *)calloc(alen, sizeof(unsigned int));
if (d == NULL) {
PyErr_NoMemory();
goto cleanup;
}
Py_BEGIN_ALLOW_THREADS
bytes2longs(data.buf, dlen, d, padding);
bytes2longs(key.buf, klen, k, 0);
btea(d, alen, k, rounds);
Py_END_ALLOW_THREADS
PyBuffer_Release(&data);
PyBuffer_Release(&key);
retval = PyString_FromStringAndSize(NULL, (alen << 2));
if (!retval) {
goto cleanup;
}
retbuf = PyString_AS_STRING(retval);
longs2bytes(d, alen, retbuf, 0);
free(d);
return retval;
cleanup:
XFREE(d);
Py_XDECREF(retval);
PyBuffer_Release(&data);
PyBuffer_Release(&key);
return NULL;
}
PyDoc_STRVAR(
xxtea_encrypt_hex_doc,
"encrypt_hex (data, key, padding=True, rounds=0)\n\n"
"Encrypt `data` with a 16-byte `key`, return hex encoded bytes.");
static PyObject *xxtea_encrypt_hex(PyObject *self, PyObject *args, PyObject *kwargs)
{
PyObject *retval, *tmp;
retval = tmp = NULL;
if (!(tmp = xxtea_encrypt(self, args, kwargs))) {
return NULL;
}
retval = PyObject_CallMethod(binascii, "hexlify", "(O)", tmp, NULL);
Py_DECREF(tmp);
return retval;
}
PyDoc_STRVAR(
xxtea_decrypt_doc,
"decrypt (data, key, padding=True, rounds=0)\n\n"
"Decrypt `data` with a 16-byte `key`, return original bytes.");
static PyObject *xxtea_decrypt(PyObject *self, PyObject *args, PyObject *kwargs)
{
int alen, dlen, klen, rc, padding;
PyObject *retval;
char *retbuf;
unsigned int *d, k[4], rounds;
Py_buffer data, key;
d = NULL;
retval = NULL;
k[0] = k[1] = k[2] = k[3] = 0;
padding = 1;
rounds = 0;
data.buf = data.obj = key.buf = key.obj = NULL;
if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s*s*|iI", keywords, &data, &key, &padding, &rounds)) {
return NULL;
}
padding = padding != 0 ? 1 : 0;
dlen = data.len;
klen = key.len;
if (klen != 16) {
PyErr_SetString(PyExc_ValueError, "Need a 16-byte key.");
goto cleanup;
}
if (!padding && (dlen < 8 || dlen & 3)) {
PyErr_SetString(PyExc_ValueError, "Data length must be a multiple of 4 bytes and must not be less than 8 bytes");
goto cleanup;
}
retval = PyString_FromStringAndSize(NULL, dlen);
if (!retval) {
goto cleanup;
}
retbuf = PyString_AS_STRING(retval);
/* not divided by 4, or length < 8 */
if (dlen & 3 || dlen < 8) {
PyErr_SetString(PyExc_ValueError, "Invalid data, data length is not a multiple of 4, or less than 8.");
goto cleanup;
}
alen = dlen / 4;
d = (unsigned int *)calloc(alen, sizeof(unsigned int));
if (d == NULL) {
PyErr_NoMemory();
goto cleanup;
}
Py_BEGIN_ALLOW_THREADS
bytes2longs(data.buf, dlen, d, 0);
bytes2longs(key.buf, klen, k, 0);
btea(d, -alen, k, rounds);
rc = longs2bytes(d, alen, retbuf, padding);
Py_END_ALLOW_THREADS
PyBuffer_Release(&data);
PyBuffer_Release(&key);
if (padding) {
if (rc >= 0) {
/* Remove PKCS#7 padded chars */
Py_SET_SIZE(retval, rc);
}
else {
/* Illegal PKCS#7 padding */
PyErr_SetString(PyExc_ValueError, "Invalid data, illegal PKCS#7 padding. Could be using a wrong key.");
goto cleanup;
}
}
free(d);
return retval;
cleanup:
XFREE(d);
Py_XDECREF(retval);
PyBuffer_Release(&data);
PyBuffer_Release(&key);
return NULL;
}
PyDoc_STRVAR(
xxtea_decrypt_hex_doc,
"decrypt_hex (data, key, padding = True)\n\n"
"Decrypt hex encoded `data` with a 16-byte `key`, return original bytes.");
static PyObject *xxtea_decrypt_hex(PyObject *self, PyObject *args, PyObject *kwargs)
{
PyObject *data, *key, *padding, *rounds, *retval, *tmp;
data = key = retval = tmp = NULL;
padding = Py_BuildValue("i", 1);
rounds = Py_BuildValue("I", 0);
if (!PyArg_ParseTupleAndKeywords(args, kwargs, "SS|OO", keywords, &data, &key, &padding, &rounds)) {
goto cleanup;
}
if (!(tmp = PyObject_CallMethod(binascii, "unhexlify", "(O)", data, NULL))) {
goto cleanup;
}
retval = PyObject_CallMethod(module, "decrypt", "(OOOO)", tmp, key, padding, rounds, NULL);
Py_DECREF(tmp);
return retval;
cleanup:
Py_DECREF(padding);
Py_DECREF(rounds);
return NULL;
}
/*****************************************************************************
* Module Init ****************************************************************
****************************************************************************/
/* ref: https://docs.python.org/2/howto/cporting.html */
static PyMethodDef methods[] = {
{"encrypt", (PyCFunction)xxtea_encrypt, METH_VARARGS | METH_KEYWORDS, xxtea_encrypt_doc},
{"decrypt", (PyCFunction)xxtea_decrypt, METH_VARARGS | METH_KEYWORDS, xxtea_decrypt_doc},
{"encrypt_hex", (PyCFunction)xxtea_encrypt_hex, METH_VARARGS | METH_KEYWORDS, xxtea_encrypt_hex_doc},
{"decrypt_hex", (PyCFunction)xxtea_decrypt_hex, METH_VARARGS | METH_KEYWORDS, xxtea_decrypt_hex_doc},
{NULL, NULL, 0, NULL}
};
static struct PyModuleDef moduledef = {
PyModuleDef_HEAD_INIT,
"xxtea",
NULL,
-1,
methods,
NULL,
NULL,
NULL,
NULL
};
PyObject *PyInit_xxtea(void)
{
module = PyModule_Create(&moduledef);
if (module == NULL) {
return NULL;
}
if (!(binascii = PyImport_ImportModule("binascii"))) {
Py_DECREF(module);
return NULL;
}
PyModule_AddStringConstant(module, "VERSION", VERSION);
return module;
}