X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/f9520103d3b3a1a36fdb30a46aa4f6c1cd3f1c9e..b62348ce5b869bfc2427c2d4b0eb57d7f3e1f3b2:/windows/winnoise.c

diff --git a/windows/winnoise.c b/windows/winnoise.c
index affb1a52..31364546 100644
--- a/windows/winnoise.c
+++ b/windows/winnoise.c
@@ -9,10 +9,18 @@
 #include "ssh.h"
 #include "storage.h"
 
+#include <wincrypt.h>
+
+DECL_WINDOWS_FUNCTION(static, BOOL, CryptAcquireContextA,
+                      (HCRYPTPROV *, LPCTSTR, LPCTSTR, DWORD, DWORD));
+DECL_WINDOWS_FUNCTION(static, BOOL, CryptGenRandom,
+                      (HCRYPTPROV, DWORD, BYTE *));
+DECL_WINDOWS_FUNCTION(static, BOOL, CryptReleaseContext,
+                      (HCRYPTPROV, DWORD));
+static HMODULE wincrypt_module = NULL;
+
 /*
- * This function is called once, at PuTTY startup, and will do some
- * seriously silly things like listing directories and getting disk
- * free space and a process snapshot.
+ * This function is called once, at PuTTY startup.
  */
 
 void noise_get_heavy(void (*func) (void *, int))
@@ -20,6 +28,7 @@ void noise_get_heavy(void (*func) (void *, int))
     HANDLE srch;
     WIN32_FIND_DATA finddata;
     DWORD pid;
+    HCRYPTPROV crypt_provider;
     char winpath[MAX_PATH + 3];
 
     GetWindowsDirectory(winpath, sizeof(winpath));
@@ -35,6 +44,24 @@ void noise_get_heavy(void (*func) (void *, int))
     pid = GetCurrentProcessId();
     func(&pid, sizeof(pid));
 
+    if (!wincrypt_module) {
+        wincrypt_module = load_system32_dll("advapi32.dll");
+        GET_WINDOWS_FUNCTION(wincrypt_module, CryptAcquireContextA);
+        GET_WINDOWS_FUNCTION(wincrypt_module, CryptGenRandom);
+        GET_WINDOWS_FUNCTION(wincrypt_module, CryptReleaseContext);
+    }
+
+    if (wincrypt_module && p_CryptAcquireContextA &&
+        p_CryptGenRandom && p_CryptReleaseContext &&
+        p_CryptAcquireContextA(&crypt_provider, NULL, NULL, PROV_RSA_FULL,
+                               CRYPT_VERIFYCONTEXT)) {
+        BYTE buf[32];
+        if (p_CryptGenRandom(crypt_provider, 32, buf)) {
+            func(buf, sizeof(buf));
+        }
+        p_CryptReleaseContext(crypt_provider, 0);
+    }
+
     read_random_seed(func);
     /* Update the seed immediately, in case another instance uses it. */
     random_save_seed();