commit 6d0b14fea3c2cf96c625203debb4416c6b7896d7 Author: George Kadianakis desnacked@riseup.net Date: Thu May 25 16:03:46 2017 +0300

prop224: Specify blinding factor clamping. --- proposals/224-rend-spec-ng.txt | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)

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