nwztools/upgtools: rewrite keysig brute force search

The new search has two new features:
- it takes advantage of the fact that DES keys are only 56-bit long (and not 64)
- it is now multithreaded
As a proof of concept, I ran it on the A10 series firmware upgrade and was able
to find the key in a few seconds using 4 threads. The search is still limited
to ascii hex passwords (seems to work on all devices I have tried thus far).

Change-Id: Ied080286d2bbdc493a6ceaecaaadba802b429666

1 files changed, 6 insertions, 7 deletions

diff --git a/utils/nwztools/upgtools/mg.cpp b/utils/nwztools/upgtools/mg.cpp
index 21659ff..f02b673 100644
--- a/utils/nwztools/upgtools/mg.cpp
+++ b/utils/nwztools/upgtools/mg.cpp
@@ -28,24 +28,23 @@
 using namespace CryptoPP;
 namespace
 {
-    ECB_Mode< DES >::Decryption g_dec;
-    ECB_Mode< DES >::Encryption g_enc;
-
     inline int dec_des_ecb(void *in, int size, void *out, uint8_t *key)
     {
+        ECB_Mode< DES >::Decryption dec;
         if(size % 8)
             return 42;
-        g_dec.SetKey(key, 8);
-        g_dec.ProcessData((byte*)out, (byte*)in, size);
+        dec.SetKey(key, 8);
+        dec.ProcessData((byte*)out, (byte*)in, size);
         return 0;
     }
 
     inline int enc_des_ecb(void *in, int size, void *out, uint8_t *key)
     {
+        ECB_Mode< DES >::Encryption enc;
         if(size % 8)
             return 42;
-        g_enc.SetKey(key, 8);
-        g_enc.ProcessData((byte*)out, (byte*)in, size);
+        enc.SetKey(key, 8);
+        enc.ProcessData((byte*)out, (byte*)in, size);
         return 0;
     }
 }