Re: SSH1 key recovery patch

[Pavel Machek <pavel () UCW CZ>]

Hi!

>  --- rsaglue.c   Wed Jan 17 11:42:52 2001
> +++ rsaglue.c   Tue Feb 13 16:05:33 2001
> @@ -264,8 +264,10 @@
>    mpz_clear(&aux);
>
>    if (value[0] != 0 || value[1] != 2)
> +  {
> +    kill(getppid(),SIGALRM);
>      fatal("Bad result from rsa_private_decrypt");
> -
> +  }
>    for (i = 2; i < len && value[i]; i++)
>      ;
>
> --- sshd.c      Wed Jan 17 11:42:53 2001
> +++ sshd.c      Tue Feb 13 16:05:15 2001
> @@ -757,9 +757,11 @@
>
>  RETSIGTYPE key_regeneration_alarm(int sig)
>  {
> +  static time_t last_keygen_time=0;
>    /* Check if we should generate a new key. */
> -  if (key_used)
> -    {
> +  if (key_used &&  (time(NULL) - last_keygen_time > 60))
> +   {
> +      last_keygen_time = time(NULL);
>        /* This should really be done in the background. */
>        log_msg("Generating new %d bit RSA key.", options.server_key_bits);
>
> random_acquire_light_environmental_noise(&sensitive_data.random_state);

This is still not good.

You changed time from hour to minute+time it takes for signal to be
delivered. That only means faster server is needed for this to be
exploitable.
                                                                Pavel
--
I'm pavel () ucw cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at discuss () linmodems org