Re: Key Usage in ISO 15782

["Simonetti David" <simonetti_david@xxxxxxx>]

Hans,

You make good points...

Hans Nilsson wrote:
> 
> Blake,
> 
> Now that I have looked up "ephemeral" in a dictionary (it means short-lived,
> "only for a day", just like those beautiful insects), I think that the
> definitions a) and b) are good.
> 
> However, I can then not understand why the document later states that "When
> the nonRepudiation bit is set, the digitalSignature bit shall always be set"

I agree that this is inconsistent, and perhaps is exactly reversed.  

> 
> Of course, one should be allowed to specify that a key ONLY should be used
> for long-term signatures (non-repudiation) and not anything else. When both
> bits are set, as required in 15782, it means that the key always may be used
> for ephemeral data also.

I agree that 15782 is inconsistent.

> 
> And the statement above is also in conflict with the new table 8, where ANY
> combination is allowed for the two bits in combinations 1 and 2 (and I can
> see no difference between combination 1 and 2!)

Agreed.

> 
> I think this should be changed in 15782 (and consequently in the German
> spec), by
> - deleting the sentence above
> - allowing just one bit in each of combinations 1 and 2 (digSignature and
> nonRepudiation respectively)
> 
> Hans

If I recall the requirements and the consensus of the Banking WG
correctly, then nonRepudiation may be set independently of any other
usage, but when digitalSignature is set then nonRepudiation should also
be set absent conflicting business requirements (because financial
transactions always implement some action for sake of non-repudiation).

-- 
David Simonetti, Booz·Allen & Hamilton Inc.