[Swan-dev] what key-lengths to propose for IKEv2 ike=aes-... and esp=aes-...

Andrew Cagney andrew.cagney at gmail.com
Mon Nov 28 16:59:01 UTC 2016


Given IKEv2 config lines like:

    ike=aes-...
    esp=aes-...

i.e., when no key length was explicitly specified, then pluto will propose:

   ike: aes_256 then aes_128
   esp: aes_128 then aes_256

i.e., ike and esp have key-lengths in the opposite order

The behaviour is long standing - tests require this - but I'm left
wondering how much of this still makes sense.

Details:

For the case when there is no explicit key length, and it isn't 3DES,
IKEv2 will propose one (same) or both (different) of:
  - keydeflen
  - keymaxlen (aka max(encrypt->key_bit_lengths[]))
with the order being determined by IKE vs ESP.

Andrew


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