Changeset 5 for src/nextrand.c

Timestamp:

10/17/12 19:52:34 (12 years ago)

Author:

tmorgan

Message:

made nextrand more user friendly

File:

• src/nextrand.c (modified) (3 diffs)

src/nextrand.c

@@ -5 +5 @@
 Copyright (C) 2012 Virtual Security Research, LLC
 Author: Dan J. Rosenberg
+Updates by: Timothy D. Morgan
 
  This program is free software: you can redistribute it and/or modify
@@ -30 +31 @@
 int nextInt()
 {
-
-        seed = (seed * MULTIPLIER + ADDEND) & MASK;
-        return (int) (seed >> 16);
-
+  seed = (seed * MULTIPLIER + ADDEND) & MASK;
+  return (int) (seed >> 16);
 }
 
@@ -39 +38 @@
 int main(int argc, char **argv)
 {
-
-        int i, num;
-        unsigned long long r1, r2;
-
-
-        if (argc != 4) {
-                printf("[-] Usage: %s rand1 rand2 num\n", argv[0]);
-                return 1;
-        }
-
-        r1 = atoi(argv[1]);
-        r2 = atoi(argv[2]);
-        num = atoi(argv[3]);
-
-        for (i = 0; i < 65536; i++) {
-                seed = (r1 << 16) + i;
-                if ((unsigned int)(((seed * MULTIPLIER + ADDEND) & MASK) >> 16) == (unsigned int)r2) {
-                        break;
-                }
-                seed = 0;
-        }
-
-        if (!seed) {
-                printf("[-] Seed not found.\n");
-                return 1;
-        }
-
-        /* Uncomment to print the first two values, which were already provided */
-//      printf("%d\n", (int)r1);
-//      printf("%d\n", nextInt());
-
-        for (i = 0; i < num; i++) {
-                printf("%d\n", nextInt());
-        }
-
-        return 0;
-
+  int i, num;
+  unsigned long long r1, r2;
+  
+  if (argc != 4) 
+  {
+    fprintf(stderr, "[-] Usage: %s rand1 rand2 num\n", argv[0]);
+    fprintf(stderr, 
+            "[-] Note that rand1 and rand2 must be signed integers returned in sequence\n"
+            "    from a single Java Random instance.  Values provided must be generated\n"
+            "    by Random.nextInt() which was called with no arguments.\n");
+    return 1;
+  }
+  
+  r1 = atoi(argv[1]);
+  r2 = atoi(argv[2]);
+  num = atoi(argv[3]);
+  
+  for (i = 0; i < 65536; i++) 
+  {
+    seed = (r1 << 16) + i;
+    if ((unsigned int)(((seed * MULTIPLIER + ADDEND) & MASK) >> 16) == (unsigned int)r2) 
+      break;
+    
+    seed = 0;
+  }
+  
+  if (!seed) {
+    fprintf(stderr, "[-] Seed not found.\n");
+    return 1;
+  }
+  
+  fprintf(stderr, "[+] Seed %.12llX found based on provided values: ", seed);
+  fprintf(stderr, "%d %d\n", (int)r1, nextInt());
+  fprintf(stderr, "[+] Next %d values:\n", num);
+  
+  for (i = 0; i < num; i++) 
+    printf("%d\n", nextInt());
+  
+  return 0;
 }