authentication and ESP

[Sandy Harris]

John S. Denker wrote:
> On 06/19/2003 01:49 PM, martin f krafft wrote:
>  > As far as I can tell, IPsec's ESP has the functionality of
>  > authentication and integrity built in:
> 
> It depends on what you mean by "built in".
>  1) The RFC provides for ESP+authentication but
> does not require ESP to use authentication.
>  2) Although the RFC allows ESP without
> authentication, typical implementations are
> less flexible.  In FreeS/WAN for instance, if
> you ask for ESP will get ESP+AH.
> 
> ESP without authentication may be vulnerable to
> replay attacks and/or active attacks that tamper
> with the bits in transit.  The degree of vulnerability
> depends on details (type of chaining, higher-level
> properties of payload, ...).

There's some discussion and links in the FreeS/WAN
docs:
http://www.freeswan.org/freeswan_trees/freeswan-2.00/doc/ipsec.html#encnoauth




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