prop224: Hash time period length wherever we use period_num.

See review point:
    https://gitlab.com/dgoulet/tor/merge_requests/27#note_27696937

1 files changed, 11 insertions, 7 deletions

diff --git a/proposals/224-rend-spec-ng.txt b/proposals/224-rend-spec-ng.txt
index 8945239..2156f39 100644
--- a/proposals/224-rend-spec-ng.txt
+++ b/proposals/224-rend-spec-ng.txt
@@ -784,17 +784,20 @@ Table of contents:
             hs_index(replicanum) = H("store-at-idx" |
                                      blinded_public_key |
                                      INT_8(replicanum) |
+                                     INT_8(period_length) |
                                      INT_8(period_num) )
 
-   where blinded_public_key is specified in section [KEYBLIND], and period_num
-   is calculated using the current consensus "valid-after" as specified in
-   section [TIME-PERIODS].
+   where blinded_public_key is specified in section [KEYBLIND], period_length
+   is the length of the time period in minutes, and period_num is calculated
+   using the current consensus "valid-after" as specified in section
+   [TIME-PERIODS].
 
    Then, for each node listed in the current consensus with the HSDirV3 flag,
    we compute a directory index for that node as:
 
            hsdir_index(node) = H("node-idx" | node_identity |
                                  shared_random_value |
+                                 INT_8(period_length) |
                                  INT_8(period_num) )
 
    where shared_random_value is the shared value generated by the authorities
@@ -903,10 +906,11 @@ Table of contents:
 
    To do so, Tor clients and services use:
 
-     SRV = H("shared-random-disaster" | INT_8(period_num))
+     SRV = H("shared-random-disaster" | INT_8(period_length) | INT_8(period_num))
 
-   where period_num is calculated as specified in [TIME-PERIODS] for the
-   wanted shared random value that could not be found originally.
+   where period_length is the length of a time period in minutes, period_num is
+   calculated as specified in [TIME-PERIODS] for the wanted shared random value
+   that could not be found originally.
 
 2.3.2. Hidden services and changing shared random values
 
@@ -2052,7 +2056,7 @@ Appendix A. Signature scheme with key blinding [KEYBLIND]
   proof of this scheme.
 
   (To use this with Tor, set N = "key-blind" | INT_8(period-number) |
-  INT_8(Start of period in seconds since epoch).)
+  INT_8(period_length).)
 
 Appendix B. Selecting nodes [PICKNODES]