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klassert merged 2 commits into from
Jun 25, 2025
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WIP eesp.org AAD changes. #6

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eesp.org AAD changes.
antonyantony Feb 24, 2025
7da7f9e
mandatory-to-implement refer to rfc 8221
antonyantony Jun 24, 2025
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136 changes: 120 additions & 16 deletions eesp.org
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Original file line number Diff line number Diff line change
Expand Up @@ -526,10 +526,112 @@ padding, this too MUST be specified in that RFC.
** Integrity Check Value (ICV)

The Integrity Check Value is a variable-length field computed over
the EESP header, and Payload. The length of the field is
specified by the algorithm selected and associated with the
SA. The algorithm specification MUST specify the length of
the ICV and the comparison rules and processing steps for validation.
the Encrypted Payload and Additional Authenticated Data, as defined
in [ADD Construction]. The length of the field is specified by the
algorithm selected and associated with the SA. The algorithm
specification MUST specify the length of the ICV and the comparison
rules and processing steps for validation.


** AAD Construction
Additional Authenticated Data (AAD) includes the Base
Header, any Optional Headers and Peer Header.

#+caption: EESP AAD
#+name: eesp-aad
#+begin_src
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
| | |
~ Base Header ~ |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Int
| | egr
~ Peer Header (variable) ~ ity
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Pro
| | tec
~ Encrypted Payload Data (variable) ~ ted
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
~ Integrity Check Value-ICV (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
#+end_src

Additionally, if a Crypt Offset is used, the AAD includes the
associated data exposed due to the offset. Payload Data covered
by the Crypt Offset is transmitted in the clear, but is still
included in the AAD.

#+caption: EESP Tunnel Mode AAD with Crypt Offset
#+name: eesp-aad-crypt-offset
#+begin_src
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
| | |
| Base Header ~ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++|
| Crypt Offset Optional Header | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++| Int
| | egr
~ Peer Header (variable) ~ ity
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++| Pro
| Plaintext Payload Data (variable) | tec
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++| ted
| | |
~ Encrypted Payload Data (variable) ~ |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+++--+
~ Integrity Check Value-ICV (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++
#+end_src

As an example consider a Tunnel mode SA, with replay protection
enabled and 8 bytes explicit IV carrying an IPv4 UDP packet with
crypto offset 8 (8x4 = 32 bytes). [eesp-aad-crypt-offset-example]

#+begin_src
#+caption: EESP Tunnel Mode AAD with Crypt Offset example
#+name: eesp-aad-crypt-offset-example
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|1|Version|Flags| Opt Len (4) | Session ID | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| SPI | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Crypt Offset(2) |Opt Len (4)|POffset (7)|CryptOff(8)| F | R | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Int
| Sequence number 63-32 | egr
| Sequence number 31-0 | ity
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| IV 63-32 | Pro
| IV 31-0 | tec
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ted
| Payload Info Header (Next header 4) Plain text) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| IP + UDP Headers 28 bytes Plain text | |
+---------------------------------------------------------------+ |
| Remaining Encrypted Payload Data | |
~ ~ |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
| |
~ Integrity Check Value-ICV (variable) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
#+end_src

The AAD specifications apply to all EESP cipher suites used with
EESP. This document updates [[RFC4106]] to define EESP-specific
handling of Additional Authenticated Data (AAD) when using
AES-GCM. For AES-GMAC [[RFC4543]], the AAD includes all headers,
i.e. the entire EESP payload except the Integrity Check Value (ICV).
This document also updates AAD processing for the
ENCR_CHACHA20_POLY1305 cipher suite, as specified in [[RFC7634]].

** Full and Optimized Packet Formats

Expand Down Expand Up @@ -936,7 +1038,8 @@ intermediate devices.

*** EESP Crypt Offset Option
This option is typically used for within one Datacenter use case
such as [[PSP]].
such as [[PSP]]. When enabled full packet format, with Payload Info
Header MUST be used; for the intermediate router to have Next Header.

NOTE: This is for the use in Datacenters ONLY. It might be moved to
a separate document that defines the 'EESP use for Datacenters'.
Expand Down Expand Up @@ -1178,7 +1281,7 @@ packets.
** Algorithms

# :NOTE: Not all AEAD algorithms provide both services, e.g.
# ENCR_NULL_AUTH_AES_GMAC (RFC 4543) does not provide confidentiality
# ENCR_NULL_AUTH_AES_GMAC [[RFC4543]] does not provide confidentiality

EESP version 0 specifies combined mode algorithms only. Separate
confidentiality and integrity algorithms MUST NOT be used with
Expand All @@ -1190,9 +1293,10 @@ using separate confidentiality and integrity algorithms becomes
necessary, a new version of EESP MUST be defined.

The mandatory-to-implement algorithms for use with EESP described
in a separate RFC (TBD), to facilitate updating the algorithm requirements
independently from the protocol per se. Additional algorithms,
beyond those mandated for EESP, MAY be supported.
in a separate RFC, for e.g. RFC8221bis or another I.D., to facilitate
updating the algorithm requirements independently from the protocol
per se. Additional algorithms, beyond those mandated for EESP, MAY
be supported.

*** Combined Mode Algorithms

Expand Down Expand Up @@ -1716,12 +1820,11 @@ overflow were imminent. Thus, a compliant implementation SHOULD NOT
provide anti-replay service in conjunction with SAs that are manually
keyed.

The mandatory-to-implement algorithms for use with EESP are described
in a separate document RFC (TBD),
# [[RFC4305]] is for ESP
to facilitate updating the algorithm
requirements independently from the protocol per se. Additional
algorithms, beyond those mandated for EESP, MAY be supported.
The mandatory-to-implement algorithms for use with EESP described
in a separate RFC, for e.g. RFC8221bis or another I.D., to facilitate
updating the algorithm requirements independently from the protocol
per se. Additional algorithms, beyond those mandated for EESP, MAY
be supported.

#Because use of encryption in EESP is optional, support for the "NULL"
#encryption algorithm also is required to maintain consistency with
Expand Down Expand Up @@ -1835,7 +1938,6 @@ TBD
** RFC2119
** RFC4301
** RFC4303
** RFC4305
** RFC4494
** RFC7296
** RFC8200
Expand All @@ -1851,6 +1953,8 @@ TBD
** RFC3948
** RFC4106
** RFC8750
** RFC4543
** RFC7634
** PSP
:PROPERTIES:
:REF_TARGET: https://github.com/google/psp/blob/main/doc/PSP_Arch_Spec.pdf
Expand Down