changelog: work on documentation of changes since ea31544cc33a

[secnet.git] / NOTES

diff --git a/NOTES b/NOTES
index 8f92f6911fa203ec97f38dbec352fabb77655895..001c118e96f9401592560ea3332583b653ac2c55 100644 (file)
--- a/NOTES
+++ b/NOTES
@@ -269,6 +269,12 @@ initial subset of the following list of items:
    abilities of the sender.
  * In MSG3/MSG4: a 16-bit integer being the sender's MTU, or zero.
    (In other messages: nothing.)  See below.
+ * In MSG2/MSG3: a list of the peer's public keys that the sender will
+   accept: (i) a 1-byte integer count (ii) that many 5-byte key ids.
+   If not present, implicitly only the special key id 0000000000.
+ * In MSG3/MSG4: an 8-bit integer being an index into the
+   receiver's public key acceptance list, with which the message
+   is signed.  If not present, implicitly the key id 00000000000.
  * More data which is yet to be defined and which must be ignored
    by receivers.
 The optional additional data after the receiver's name is not
@@ -278,14 +284,11 @@ Capability flag bits must be in one the following two categories:
 
 1. Early capability flags must be advertised in MSG1 or MSG2, as
    applicable.  If MSG3 or MSG4 advertise any "early" capability bits,
-   MSG1 or MSG3 (as applicable) must have advertised them too.  Sadly,
-   advertising an early capability flag will produce MSG1s which are
-   not understood by versions of secnet which predate the capability
-   mechanism.
-
-2. Late capability flags are advertised in MSG2 or MSG3, as
-   applicable.  They may also appear in MSG1, but this is not
-   guaranteed.  MSG4 must advertise the same set as MSG2.
+   MSG1 or MSG3 (as applicable) must have advertised them too.
+
+2. Late capability flags may be advertised only in MSG2 or MSG3, as
+   applicable.  They are only in MSG1 with newer secnets; older
+   versions omit them.  MSG4 must advertise the same set as MSG2.
 
 Currently, the low 16 bits are allocated for negotiating bulk-crypto
 transforms.  Bits 8 to 15 are used by Secnet as default capability