Is 80 bits enough? [Re: Advantages and disadvantages of using CB64 type of identifiers]

Christian Huitema wrote:
...
> 
> Everybody should be convinced that, when it comes to cryptography, 2^64
> is actually a small number. SEND alleviates this risk by
> cryptographically link a public key to the entire 128 bits of the
> address. This is NOT overkill.

But is 2^80 big enough? Omitting the /48 prefix from the crypto would
avoid the hash changing when rehoming to a different prefix.

    Brian