diff --git a/src/tools/gethash.c b/src/tools/gethash.c
new file mode 100644
index 000000000..65fc1ef76
--- /dev/null
+++ b/src/tools/gethash.c
@@ -0,0 +1,23 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+int main(int argc, char ** argv)
+{
+  char key[4];
+  char code[4];
+  char result[4];
+  int a, i, rot;
+  for (a=1;a<argc;++a) {
+    const char * str = argv[a];
+    size_t len = strlen(str);
+    str = str+len-6;
+    memcpy(key, str, 3);
+    memcpy(code, str+3, 3);
+    result[3] = key[3] = code[3] = 0;
+    rot=atoi(key);
+    for(i=0;i!=3;++i) result[(i+rot)%3] = ((code[i]+10-key[i])%10)+'0';
+    printf("%s %s\n", argv[a], result);
+  }
+  return 0;
+}