On 2/27/2015 9:51 PM, Jason Edgecombe wrote:
> ** file server option to force authenticated access to use encryption

A file server cannot force authenticated access from a client to use
encryption.  The client chooses the property of the connection and uses
that to send data to the file server prior to the file server deciding
whether or not to issue an authentication challenge.

The client needs to be told the connection policy prior to connection
establishment (that is what "fs setcrypt" does).  A file server can
choose to ignore a connection but by that time the data you wish to be
secure has already been transmitted in the clear.  If the connection is
rejected by the file server and the clear retransmits the same request
using a new encryption connection, the client has now given known
plaintext to an attacker to use to determine the encryption key.

This is where AuriStor's policy framework comes into play.  It is a
mechanism by which the clients are told ahead of time which
authentication and wire privacy modes are to be used for each file
server connection.  That way if your volume is to be accessed only using
an rxgk authenticated aes256-sha1 encrypted/integrity protected
connection the client knows what to do and the file server knows what to
enforce.  Only then can there be a guarantee that there will be no
information leakage.

Jeffrey Altman


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