Hey,
The following is a quick patch for secure pseudorandom number generator on
windows. I split the functionality with a brutal ifdef macro. Feedback on the
code and suggestions for a nicer implementation is appreciated :).
diff --git a/lib/entropy.c b/lib/entropy.c
index 02f56e0..ec9d95c 100644
--- a/lib/entropy.c
+++ b/lib/entropy.c
@@ -20,6 +20,9 @@
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
+#ifdef _WIN32
+#include <Wincrypt.h>
+#endif
#include "socket-util.h"
#include "vlog.h"
@@ -33,6 +36,7 @@ static const char urandom[] = "/dev/urandom";
int
get_entropy(void *buffer, size_t n)
{
+#ifndef _WIN32
size_t bytes_read;
int error;
int fd;
@@ -49,6 +53,20 @@ get_entropy(void *buffer, size_t n)
if (error) {
VLOG_ERR("%s: read error (%s)", urandom, ovs_retval_to_string(error));
}
+#else
+ int error = 1;
+ HCRYPTPROV crypt_prov = 0;
+ CryptAcquireContext(&crypt_prov, NULL, NULL, PROV_RSA_FULL, 0);
+
Microsoft documentation suggests using CRYPT_VERIFYCONTEXT. Although, I haven't
tested to see what sort of an impact this will have.
http://msdn.microsoft.com/en-us/library/windows/desktop/aa379886(v=vs.85).aspx
For performance reasons, we recommend that you set the pszContainer parameter
to NULL and the dwFlags parameter to CRYPT_VERIFYCONTEXT in all situations
where you do not require a persisted key. In particular, consider setting the
pszContainer parameter to NULL and the dwFlags parameter to CRYPT_VERIFYCONTEXT
for the following scenarios:
+ if (CryptGenRandom(crypt_prov, n, buffer)) {
+ error = 0;
+ }
+
+ if (error) {
+ VLOG_ERR("CryptGenRandom: read error (%s)", urandom,
ovs_retval_to_string(error));
+ }
How about doing instead -
int error = 0;
If (! CryptGetRandom(crypt_prov, n, buffer)) {
error = GetLastError();
VLOG_ERR("CryptGenRandom: read error (%s)", urandom,
ovs_retval_to_string(error));
}
+ CryptReleaseContext(crypt_prov, 0);
+#endif
return error;
}
Kind Regards,
Alin.
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