ESP
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... In transport mode, the IPsec Encapsulating Security Payload (ESP) or
Authentication Header (AH ...
... receiver first applies
the IPsec transform (e.g., ESP) and then matches the packet against
the Security Parameter Index (SPI ...
... receiver first applies the IPsec transform (e.g.,
ESP) and then matches the packet against the SPI and the inbound
selectors associated with the SA ...
...
For the purposes of this document, where the confidentiality of ESP
[RFC4303] is not required, AH ...
... AH [RFC4302] can be used as an alternative
to ESP. The main difference is that AH is able to provide integrity
protection for certain fields in the outer IPv4 ...
... confidentiality without integrity is
discouraged. ESP furthermore provides limited traffic flow
confidentiality.
...
... Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M. Stenberg, "UDP Encapsulation of IPsec ESP Packets", RFC 3948prop, January 2005. ...