[rc5] The unknown message is...

[Lutz Donnerhacke]

David McNett wrote:
> It is a great privilege and we are excited to announce that at 13:25
> GMT on 19-Oct-1997, we found the correct solution for RSA Labs’ RC5-
> 32/12/7 56-bit secret-key challenge.  Confirmed by RSA Labs, the key
> 0x532B744CC20999 presented us with the plaintext message for which we
> have been searching these past 250 days.
> 
> The unknown message is: It’s time to move to a longer key length

By coincidence, I happened to be surfing through some old CPUNX
archives today, and came across the following:

> From: Tim May
> Date: Wed, 22 Jan 1990 16:14:52 -0500
> To: cypherpunks at toad.com
>
> I bet if there was ever an RC5-32/12/7 56-bit secret key challenge,
> that the unknown message would be: "It's time to move to a longer
> key length."
>
> Tim May
> "The Cypherpunks have shown their hand: They are going to start 
>  a mailing list."

How does he _do_ that?