[pyOpenSSL] rand.bytes, rand.pseudo_bytes

[Toni A. <to...@so...>]

Hi,

i'd like to access the OpenSSL PRNG, but neither RAND_bytes() nor
RAND_pseudo_bytes() have been implemented in OpenSSL.rand, so here
is a patch which adds them.

Index: src/rand/rand.c
===================================================================
RCS file: /u/cvs/pyopenssl/pyOpenSSL/src/rand/rand.c,v
retrieving revision 1.10
diff -u -U1 -r1.10 rand.c
--- src/rand/rand.c	8 Jul 2002 11:06:01 -0000	1.10
+++ src/rand/rand.c	11 Feb 2003 03:12:11 -0000
@@ -11,2 +11,14 @@
 #include <Python.h>
+#include "../util.h"
+
+PyObject *rand_Error;
+
+#ifdef exception_from_error_queue
+#  undef exception_from_error_queue
+#endif
+#define exception_from_error_queue()    do { \
+    PyObject *errlist = error_queue_to_list(); \
+    PyErr_SetObject(rand_Error, errlist); \
+    Py_DECREF(errlist); \
+} while (0)
 
@@ -79,2 +91,88 @@
 
+/*
+       RAND_bytes() is available in all versions of SSLeay and
+       OpenSSL.  It has a return value since OpenSSL 0.9.5.
+       RAND_pseudo_bytes() was added in OpenSSL 0.9.5.
+*/
+static char rand_bytes_doc[] = "\n\
+Produce cryptographically strong pseudo-random bytes.\n\
+An error occurs if the PRNG has not been seeded with enough\n\
+randomness to ensure an unpredictable byte sequence.\n\
+\n\
+Arguments: spam - Always NULL\n\
+           args - The Python argument tuple, should be:\n\
+             num  - How many bytes to produce\n\
+Returns:   A string of pseudo-random bytes. Throws a rand.Error\n\
+           exception if there wasn't enough randomness\n\
+";
+
+static PyObject *
+rand_bytes(PyObject *spam, PyObject *args)
+{
+    int num, rc;
+    PyObject *rv;
+    unsigned char *buf;
+
+    if (!PyArg_ParseTuple(args, "i:bytes", &num))
+        return NULL;
+
+    buf = (unsigned char *) PyMem_NEW(unsigned char *, num);
+    if (!buf) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    rc = RAND_bytes(buf, num);
+    if (rc != 1) {
+        exception_from_error_queue();
+        return NULL;
+    }
+    rv = Py_BuildValue("s#", buf, num);
+    PyMem_DEL(buf);
+    return rv;
+}
+
+static char rand_pseudo_bytes_doc[] = "\n\
+Produce pseudo-random bytes.\n\
+Pseudo-random byte sequences generated by pseudo_bytes()\n\
+will be unique if they are of sufficient length, but are not\n\
+necessarily unpredictable. They can be used for non-cryptographic\n\
+purposes and for certain purposes in cryptographic protocols, but\n\
+usually not for key generation etc.\n\
+\n\
+Arguments: spam - Always NULL\n\
+           args - The Python argument tuple, should be:\n\
+             num  - How many bytes to produce\n\
+Returns:   A string of pseudo-random bytes\n\
+";
+
+static PyObject *
+rand_pseudo_bytes(PyObject *spam, PyObject *args)
+{
+    int num, rc;
+    PyObject *rv;
+    unsigned char *buf;
+
+    if (!PyArg_ParseTuple(args, "i:pseudo_bytes", &num))
+        return NULL;
+
+    buf = (unsigned char *) PyMem_NEW(unsigned char *, num);
+    if (!buf) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    rc = RAND_pseudo_bytes(buf, num);
+    /*
+        RAND_pseudo_bytes() returns 1 if the bytes generated are
+        cryptographically strong, 0 otherwise.
+
+        Maybe this should return a list in order to pass the
+        RAND_pseudo_bytes() return value.
+    */
+    rv = Py_BuildValue("s#", buf, num);
+    PyMem_DEL(buf);
+    return rv;
+}
+
 static char rand_status_doc[] = "\n\
@@ -211,2 +309,4 @@
     { "seed",      (PyCFunction)rand_seed,         METH_VARARGS, rand_seed_doc },
+    { "bytes",     (PyCFunction)rand_bytes,        METH_VARARGS, rand_bytes_doc },
+    { "pseudo_bytes", (PyCFunction)rand_pseudo_bytes, METH_VARARGS, rand_pseudo_bytes_doc },
     { "status",    (PyCFunction)rand_status,       METH_VARARGS, rand_status_doc },
@@ -238,2 +338,11 @@
         return;
+
+    rand_Error = PyErr_NewException("rand.Error", NULL, NULL);
+    if (rand_Error == NULL)
+        goto error;
+    if (PyModule_AddObject(module, "Error", rand_Error) != 0)
+        goto error;
+
+error:
+    ;
 }

-- 
Toni Andjelkovic
<to...@so...>