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Date: Thu, 18 Oct 2012 00:38:24 +0200
From: magnum <>
To: "" <>
Subject: Re: long-running program on bull (was: council)

On 14 Oct, 2012, at 10:54 , Dhiru Kholia <> wrote:
> This program guarantees decryption of office documents which are using RC4 40-bit encryption. Its priority can be lowered if required.
> For some reason, this program doesn't run on Solar's 8-core Xeon machine when OMP is enabled.

It crashed for me too, until I moved the #pragma up a couple of levels:

diff --git a/RC4-40-brute.c b/RC4-40-brute.c
index 30071e0..d1fcd42 100755
--- a/RC4-40-brute.c
+++ b/RC4-40-brute.c
@@ -102,7 +102,7 @@ void keyspace_search()
        struct timeval tv;
        time_t curtime;
-       int i, j, k, l, m;
+       int i, j, k;
        /* 69a3aea22c is key for test.doc */
        int is = 0x00;
        int js = 0x00;
@@ -124,11 +124,12 @@ void keyspace_search()
                        printf("%d %d @ ", i, j);
                        strftime(buffer,30,"%m-%d-%Y  %T.",localtime(&curtime));
-                       printf("%s%ld\n",buffer,tv.tv_usec);
+                       printf("%s%ld\n", buffer, (long)tv.tv_usec);
+#pragma omp parallel for
                        for(k = ks; k <= 255; k++) {
+                               int l, m;
                                for(l = ls; l <= 255; l++) {
-#pragma omp parallel for
                                        for(m = ms; m <= 255; m++) {
                                                unsigned char hashBuf[9] = { 0 };
                                                hashBuf[0] = (char)i;

Not sure why really. Anyway, the try_key() would be trivial to implement in OpenCL. I wonder how fast it would be on a good GPU? A couple of minutes on average? Only the two outermost loops in host code then. I think I'll do this soon just for phun.

So what would you do with a cracked key? Is there any free program that can use this RC4 key to unlock a document?


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