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training/htb/challenges/rev/solve.c

@@ -0,0 +1,42 @@
+#include <stdio.h>
+
+char rolling_xor(char *key, char* encrypted_data)
+{
+  char* v0 = key;
+  int v1 = 0;
+  char *i = encrypted_data;
+  char result;
+
+  for ( ; *i; ++i )
+  {
+    result = *v0;
+    *i ^= *v0++;
+    if ( ++v1 == 8 )
+    {
+      v0 = key;
+      v1 = 0;
+    }
+  }
+  return result;
+}
+
+int main(){
+  char encrypted_data[] =
+  {
+    0x09, 0x07, 0x11, 0x48, 0x20, 0x73, 0x02, 0x68, 0x2C, 0x67, 
+    0x62, 0x02, 0x3E, 0x36, 0x7D, 0x1A, 0x1E, 0x35, 0x1F, 0x07, 
+    0x2A, 0x1D, 0x3C, 0x0B, 0x71, 0x25, 0x62, 0x57, 0x7E, 0x30, 
+    0x13, 0x3B, 0x71, 0x07, 0x2E, 0x00
+  };
+
+  char key[] =
+  {
+    0x52, 0x4A, 0x4A, 0x33, 0x44, 0x53, 0x43, 0x50, 0x00
+  };
+
+
+  rolling_xor(key, encrypted_data);
+
+  printf("decrypted: %s\n", encrypted_data);
+
+}