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Import release 0.1.0
[secnet.git]
/
NOTES
diff --git
a/NOTES
b/NOTES
index a815905c425423818fc0f6d2c10c8363ee1a4ece..8e53ac71a5b44e4cb99140a8579180e467b7420f 100644
(file)
--- a/
NOTES
+++ b/
NOTES
@@
-77,14
+77,14
@@
is always fresh.
Messages:
Messages:
-1) A->B: *,iA,msg1,A,B,nA
+1) A->B: *,iA,msg1,A,B,
protorange-A,
nA
-2) B->A: iA,iB,msg2,B,A,nB,nA
+2) B->A: iA,iB,msg2,B,A,
chosen-protocol,
nB,nA
(The order of B and A reverses in alternate messages so that the same
code can be used to construct them...)
(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,nA,nB,g^x mod m}_PK_A^-1
+3) A->B: {iB,iA,msg3,A,B,
protorange-A,chosen-protocol,
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.
If message 1 was a replay then A will not generate message 3, because
it doesn't recognise nA.
@@
-92,11
+92,18
@@
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 message 2 was from an attacker then B will not generate message 4,
because it doesn't recognise nB.
-4) B->A: {iA,iB,msg4,B,A,nB,nA,g^y mod m}_PK_B^-1
+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
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.
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
5) A: iB,iA,msg5,(ping/msg5)_k
6) B: iA,iB,msg6,(pong/msg6)_k