From 6d0b14fea3c2cf96c625203debb4416c6b7896d7 Mon Sep 17 00:00:00 2001 From: George Kadianakis Date: Thu, 25 May 2017 16:03:46 +0300 Subject: prop224: Specify blinding factor clamping. --- proposals/224-rend-spec-ng.txt | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'proposals/224-rend-spec-ng.txt') diff --git a/proposals/224-rend-spec-ng.txt b/proposals/224-rend-spec-ng.txt index 6f16fce..247af87 100644 --- a/proposals/224-rend-spec-ng.txt +++ b/proposals/224-rend-spec-ng.txt @@ -2043,7 +2043,13 @@ A.2. Tor's key derivation scheme BLIND_STRING = "Derive temporary signing key" N = "key-blind" | INT_8(period-number) | INT_8(period_length) - and then do the following: + then clamp the blinding factor 'h' according to the ed25519 spec: + + h[0] &= 248; + h[31] &= 127; + h[31] |= 64; + + and do the key derivation as follows: private key for the period: a' = h a public key for the period: A' = h A = (ha)B -- cgit v1.2.3-54-g00ecf