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KE payloads in IKE
3.2 Notation
KE is the key exchange payload which contains the public
information exchanged in a Diffie-Hellman exchange. There is no
particular encoding used for the data of a KE payload.
[...]
6.3 Third Oakley Group
[...]
The data in the KE payload when using this group is the value x from
the solution (x,y), the point on the curve chosen by taking the...
Anyone mind telling me what the format is for the MODP KE payload? I
was assuming that since IKE doesn't mention anything, the following text
from draft-ietf-ipsec-oakley-02.txt was used:
g^x and g^y are encodings of group elements, where g is a special
group element indicated in the group description (see Appendix A) and
g^x indicates that element raised to the x'th power. The type of the
encoding is either a variable precision integer
[...]
APPENDIX C Encoding a variable precision integer.
Variable precision integers will be encoded as a 32-bit length field
followed by one or more 32-bit quantities containing the
representation of the integer, aligned with the most significant bit
in the first 32-bit item.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! first value word (most significant bits) !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! !
~ additional value words ~
! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ben