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#include "Python.h"
#ifdef MS_WINDOWS
/* The following #define is not needed on VC6 with the Platform SDK, and it
may not be needed on VC7, I'm not sure. I don't think it hurts anything.*/
#define _WIN32_WINNT 0x0400
#include <windows.h>
typedef BOOL (WINAPI *CRYPTACQUIRECONTEXTA)(HCRYPTPROV *phProv,\
LPCSTR pszContainer, LPCSTR pszProvider, DWORD dwProvType,\
DWORD dwFlags );
typedef BOOL (WINAPI *CRYPTGENRANDOM)(HCRYPTPROV hProv, DWORD dwLen,\
BYTE *pbBuffer );
typedef BOOL (WINAPI *CRYPTRELEASECONTEXT)(HCRYPTPROV hProv,\
DWORD dwFlags);
static PyObject* entropy(PyObject *self, PyObject *args)
{
int howMany = 0;
HINSTANCE hAdvAPI32 = NULL;
CRYPTACQUIRECONTEXTA pCryptAcquireContextA = NULL;
CRYPTGENRANDOM pCryptGenRandom = NULL;
CRYPTRELEASECONTEXT pCryptReleaseContext = NULL;
HCRYPTPROV hCryptProv = 0;
unsigned char* bytes = NULL;
PyObject* returnVal = NULL;
/* Read arguments */
if (!PyArg_ParseTuple(args, "i", &howMany))
return(NULL);
/* Obtain handle to the DLL containing CryptoAPI
This should not fail */
if( (hAdvAPI32 = GetModuleHandle("advapi32.dll")) == NULL) {
PyErr_Format(PyExc_SystemError,
"Advapi32.dll not found");
return NULL;
}
/* Obtain pointers to the CryptoAPI functions
This will fail on some early version of Win95 */
pCryptAcquireContextA = (CRYPTACQUIRECONTEXTA)GetProcAddress(hAdvAPI32,\
"CryptAcquireContextA");
pCryptGenRandom = (CRYPTGENRANDOM)GetProcAddress(hAdvAPI32,\
"CryptGenRandom");
pCryptReleaseContext = (CRYPTRELEASECONTEXT) GetProcAddress(hAdvAPI32,\
"CryptReleaseContext");
if (pCryptAcquireContextA == NULL || pCryptGenRandom == NULL ||
pCryptReleaseContext == NULL) {
PyErr_Format(PyExc_NotImplementedError,
"CryptoAPI not available on this version of Windows");
return NULL;
}
/* Allocate bytes */
if ((bytes = (unsigned char*)PyMem_Malloc(howMany)) == NULL)
return PyErr_NoMemory();
/* Acquire context */
if(!pCryptAcquireContextA(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT)) {
PyErr_Format(PyExc_SystemError,
"CryptAcquireContext failed, error %d", GetLastError());
PyMem_Free(bytes);
return NULL;
}
/* Get random data */
if(!pCryptGenRandom(hCryptProv, howMany, bytes)) {
PyErr_Format(PyExc_SystemError,
"CryptGenRandom failed, error %d", GetLastError());
PyMem_Free(bytes);
CryptReleaseContext(hCryptProv, 0);
return NULL;
}
/* Build return value */
returnVal = Py_BuildValue("s#", bytes, howMany);
PyMem_Free(bytes);
/* Release context */
if (!pCryptReleaseContext(hCryptProv, 0)) {
PyErr_Format(PyExc_SystemError,
"CryptReleaseContext failed, error %d", GetLastError());
return NULL;
}
return returnVal;
}
#elif defined(HAVE_UNISTD_H) && defined(HAVE_FCNTL_H)
#include <unistd.h>
#include <fcntl.h>
static PyObject* entropy(PyObject *self, PyObject *args)
{
int howMany;
int fd;
unsigned char* bytes = NULL;
PyObject* returnVal = NULL;
/* Read arguments */
if (!PyArg_ParseTuple(args, "i", &howMany))
return(NULL);
/* Allocate bytes */
if ((bytes = (unsigned char*)PyMem_Malloc(howMany)) == NULL)
return PyErr_NoMemory();
/* Open device */
if ((fd = open("/dev/urandom", O_RDONLY, 0)) == -1) {
PyErr_Format(PyExc_NotImplementedError,
"No entropy source found");
PyMem_Free(bytes);
return NULL;
}
/* Get random data */
if (read(fd, bytes, howMany) < howMany) {
PyErr_Format(PyExc_SystemError,
"Reading from /dev/urandom failed");
PyMem_Free(bytes);
close(fd);
return NULL;
}
/* Build return value */
returnVal = Py_BuildValue("s#", bytes, howMany);
PyMem_Free(bytes);
/* Close device */
close(fd);
return returnVal;
}
#else
static PyObject* entropy(PyObject *self, PyObject *args)
{
PyErr_Format(PyExc_NotImplementedError,
"Function not supported");
return NULL;
}
#endif
/* List of functions exported by this module */
static struct PyMethodDef entropy_functions[] = {
{"entropy", (PyCFunction)entropy, METH_VARARGS, "Return a string of random bytes produced by a platform-specific\nentropy source."},
{NULL, NULL} /* Sentinel */
};
/* Initialize this module. */
PyMODINIT_FUNC initentropy(void)
{
Py_InitModule("entropy", entropy_functions);
}
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