Shorter MAC

[vors.git] / doc / proto.texi

diff --git a/doc/proto.texi b/doc/proto.texi
index 10fb381a89f09eb2dd9841a24d2473d148c44edfdecb68fda8486a6c76ca78d2..6ebaca70c9a9119ba408a490d33e844d3329e61fb856fda1e16eac1123652521 100644 (file)
--- a/doc/proto.texi
+++ b/doc/proto.texi
@@ -11,13 +11,13 @@ dropped. 24-bit counter is long enough for very long talk sessions.
 
 Each packet is encrypted with ChaCha20-Poly1305. Key is generated during
 handshake procedure with the server and is shared among other participants.
-Packet counter is used as a nonce. Stream identifier is additional
-authenticated data.
+Stream identifier with packet counter are used as a nonce. Only 64-bits
+of Poly1305 are used.
 
 It is tuned for 32Kbps bandwidth. 24Kbps should be enough, but 40B of
-IPv6 header, +16B of Poly1305 authentication tag, +4B of stream
-identifier with the counter, +8B of UDP header for 50pps means ~28Kbps
-of bandwidth only for overhead transmission.
+IPv6 header, +8B of Poly1305 authentication tag, +4B of stream
+identifier with the counter, +8B of UDP header for 50pps means also
+24Kbps of bandwidth only for overhead transmission.
 
 Each client handshakes with the server over TCP protocol using TLS 1.3
 with curve25519 key-agreement protocol. @command{vors-keygen} generates