commit 1f0d38a7632b1861039d040089b245eba24e3318 Author: Taylor Yu catalyst@torproject.org Date: Fri Jul 20 16:56:29 2018 -0500

Clarify all-zeroes relay fingerprint behavior

The all-zeroes special case for EXTEND/EXTEND2 cells is for relay fingerprints/public keys, not cell crypto digests.

Closes ticket 26893. --- tor-spec.txt | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tor-spec.txt b/tor-spec.txt index b88befe..02bb9ae 100644 --- a/tor-spec.txt +++ b/tor-spec.txt @@ -1264,11 +1264,12 @@ see tor-design.pdf. cell to the next onion router, with the enclosed HLEN, HTYPE, and HDATA as its payload.

- As special cases, if the extend cell includes a digest of - all zeroes, or asks to extend back to the relay that sent the extend - cell, the circuit will fail and be torn down. The initiating onion - router chooses some circID not yet used on the connection between the - two onion routers. (But see section 5.1.1 above, concerning choosing + As special cases, if the EXTEND/EXTEND2 cell includes a legacy + identity, identity fingerprint, or Ed25519 identity of all zeroes, or + asks to extend back to the relay that sent the extend cell, the + circuit will fail and be torn down. The initiating onion router + chooses some circID not yet used on the connection between the two + onion routers. (But see section 5.1.1 above, concerning choosing circIDs.)

When an onion router receives a CREATE/CREATE2 cell, if it already has a