[Standards-JIG] RE: Encrypted sessions

Ian Paterson ian.paterson at clientside.co.uk
Thu Jun 8 03:18:01 UTC 2006


Jean-Louis wrote:
> The JEP-116 without "offline encryption" 
> will be even more secure, because there won't be any inter 
> session key material left to be compromised. This is what 
> real Perfect Forward Secrecy is about. 

Since the alternative is no encryption of offline messages, it could
hardly be "even more secure". ;-)

Offline messages would still benefit from Perfect Forward Secrecy,
although PFS would not start until the user came online.

> The added complexity comes in the management of crypto material
between 
> sessions (check, remove, add, etc...) just for the sake of 
> "offline encryption". Without this part, JEP-116 
> implementation is straightforward. Is the added complexity 
> worth the effort?

IMHO yes, absolutely (see above).

Note that offline encryption is already optional (MAY), so implementors
can decide for themselves.

If it makes it easier for implementors I suppose we could consider
spliting the document into two JEPs?

After all, online-only encryption is better than no encryption at all.
;-)

- Ian




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