[ntpwg] Stonger symmetric NTP authentication

[Bhatia, Manav (Manav)]

Hi David,

> As I said previously, the encoding format supports 20-octet digests 
> should somebody choose to implement it and preserve backward 
> compatibility. You cannot use an extension fielf do specify 
> the digest 
> algorithm without imposing a deadly circularity.

So, are you suggesting that we *cannot* use any hashing algorithm that
goes beyond 20 bytes? If we think there can be some backward
compatibility issues then we need to sort those out.

Cheers, Manav

> 
> There is no need to specify an additional sequence number as that 
> function is provided by the transmit timestamp and the 
> loopback check. 
> See the protocol specification for justification.
> 
> Bhatia, Manav (Manav) wrote:
> 
> > Hi,
> >
> > Is there any plan underway to use
> > HMAC-SHA-1/HMAC-SHA-256/HMAC-SHA-384/etc for NTPv4? We could use the
> > extension field header to encode the new hash digest, or it could be
> > prepared in such a way that its generic enough to support any crypto
> > algorithm. The new extension field header could also include a
> > monotonically increasing sequence number that could help 
> prevent replay
> > attacks.
> >
> > Cheers, Manav
> >
> > _______________________________________________
> > ntpwg mailing list
> > ntpwg at lists.ntp.org
> > https://lists.ntp.org/mailman/listinfo/ntpwg
> 
> 
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