From ddc1d9e0ad064de11d8bd735f7c86ab56555330e Mon Sep 17 00:00:00 2001 From: Ian Jackson Date: Thu, 25 Jul 2013 18:30:51 +0100 Subject: [PATCH] NOTES: Remove unimplemented protocol negotiation The protocol negotiation mechanism documented in NOTES is not implemented. Remove it from the document. Signed-off-by: Ian Jackson --- NOTES | 20 +++++--------------- 1 file changed, 5 insertions(+), 15 deletions(-) diff --git a/NOTES b/NOTES index 09c083e..33c010e 100644 --- a/NOTES +++ b/NOTES @@ -193,21 +193,18 @@ i? is appropriate index for receiver Note that 'i' may be re-used from one session to the next, whereas 'n' is always fresh. -The protocol version selection stuff is not yet implemented: I'm not -yet convinced it's a good idea. Instead, the initiator could try -using its preferred protocol (which starts with a different magic -number) and fall back if there's no reply. +The protocol version selection stuff is not yet implemented. Messages: -1) A->B: *,iA,msg1,A,B,protorange-A,nA +1) A->B: *,iA,msg1,A,B,nA -2) B->A: iA,iB,msg2,B,A,chosen-protocol,nB,nA +2) B->A: iA,iB,msg2,B,A,nB,nA (The order of B and A reverses in alternate messages so that the same code can be used to construct them...) -3) A->B: {iB,iA,msg3,A,B,protorange-A,chosen-protocol,nA,nB,g^x mod m}_PK_A^-1 +3) A->B: {iB,iA,msg3,A,B,nA,nB,g^x mod m}_PK_A^-1 If message 1 was a replay then A will not generate message 3, because it doesn't recognise nA. @@ -215,18 +212,11 @@ it doesn't recognise nA. If message 2 was from an attacker then B will not generate message 4, because it doesn't recognise nB. -If an attacker is trying to manipulate the chosen protocol, B can spot -this when it sees A's message 3. - -4) B->A: {iA,iB,msg4,B,A,protorange-B,chosen-protocol,nB,nA,g^y mod m}_PK_B^-1 +4) B->A: {iA,iB,msg4,B,A,nB,nA,g^y mod m}_PK_B^-1 At this point, A and B share a key, k. B must keep retransmitting message 4 until it receives a packet encrypted using key k. -A can abandon the exchange if the chosen protocol is not the one that -it would have chosen knowing the acceptable protocol ranges of A and -B. - 5) A: iB,iA,msg5,(ping/msg5)_k 6) B: iA,iB,msg6,(pong/msg6)_k -- 2.30.2