[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
[tor-commits] [torspec] 08/14: Name and clarify a few more objects.
This is an automated email from the git hooks/post-receive script.
nickm pushed a commit to branch main
in repository torspec.
commit d44927c39e16bca7c95f60fee1a2ff33f0e39500
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
AuthorDate: Tue Feb 7 15:07:57 2023 -0500
Name and clarify a few more objects.
---
rend-spec-v3.txt | 52 +++++++++++++++++++++++++++++++++++-----------------
1 file changed, 35 insertions(+), 17 deletions(-)
diff --git a/rend-spec-v3.txt b/rend-spec-v3.txt
index 76d02cf..c9928e5 100644
--- a/rend-spec-v3.txt
+++ b/rend-spec-v3.txt
@@ -603,8 +603,8 @@ Table of contents:
KP_hs_desc_sign, KS_hs_desc_sign.
Introduction point authentication key -- A short-term signing
- keypair used to identify a hidden service to a given
- introduction point. A fresh keypair is made for each
+ keypair used to identify a hidden service's session at a given
+ introduction point. The service makes a fresh keypair is made for each
introduction point; these are used to sign the request that a
hidden service host makes when establishing an introduction
point, so that clients who know the public component of this key
@@ -612,14 +612,20 @@ Table of contents:
service. No keypair is ever used with more than one introduction
point. (previously called a "service key" in rend-spec.txt)
KP_hs_ipt_sid, KS_hs_ipt_sid
- ("hidden service introduction point temporary id").
+ ("hidden service introduction point session id").
Introduction point encryption key -- A short-term encryption
keypair used when establishing connections via an introduction
- point. Plays a role analogous to Tor nodes' onion keys. A fresh
- keypair is made for each introduction point.
+ point. Plays a role analogous to Tor nodes' onion keys. The service
+ makes a fresh keypair is made for each introduction point.
KP_hss_ntor, KS_hss_ntor.
+ Ephemeral descriptor encryption key -- A short-lived encryption
+ keypair made by the service, and used to encrypt the inner layer
+ of hidden service descriptors when client authentication is in
+ use.
+ KP_hss_desc_enc, KS_hss_desc_enc
+
Symmetric keys defined in this document:
Descriptor encryption keys -- A symmetric encryption key used to
@@ -627,6 +633,12 @@ Table of contents:
current period and the hidden service credential.
K_desc_enc.
+ Nonces defined in this document:
+
+ N_hs_desc_enc -- a nonce used to derive keys to decrypt the inner
+ encryption layer of hidden service descriptors. This is
+ sometimes also called a "descriptor cookie".
+
Public/private keypairs defined elsewhere:
Onion key -- Short-term encryption keypair (KS_ntor, KP_ntor).
@@ -651,7 +663,8 @@ Table of contents:
Specifically, each authorized client possesses:
- An x25519 keypair used to compute decryption keys that allow the client to
- decrypt the hidden service descriptor. See [HS-DESC-ENC].
+ decrypt the hidden service descriptor. See [HS-DESC-ENC]. This is
+ the client's counterpart to KP_hss_desc_enc.
KP_hsc_desc_enc, KS_hsd_desc_enc.
- An ed25519 keypair which allows the client to compute signatures which
@@ -1187,10 +1200,11 @@ Table of contents:
"encrypted" field.
If client auth is enabled, the hidden service generates a fresh
- descriptor_cookie key (32 random bytes) and encrypts it using each
- authorized client's identity x25519 key. Authorized clients can use the
- descriptor cookie to decrypt the second layer of encryption. Our encryption
- scheme requires the hidden service to also generate an ephemeral x25519
+ descriptor_cookie key (`N_hs_desc_enc`, 32 random bytes) and encrypts
+ it using each authorized client's identity x25519 key. Authorized
+ clients can use the descriptor cookie (`N_hs_desc_enc`) to decrypt
+ the second (inner) layer of encryption. Our encryption scheme
+ requires the hidden service to also generate an ephemeral x25519
keypair for each new descriptor.
If client auth is disabled, fake data is placed in each of the fields below
@@ -1212,9 +1226,9 @@ Table of contents:
[Exactly once]
- This field contains an ephemeral x25519 public key generated by the
- hidden service and encoded in base64. The key is used by the encryption
- scheme below.
+ This field contains `KP_hss_desc_enc`, an ephemeral x25519 public
+ key generated by the hidden service and encoded in base64. The key
+ is used by the encryption scheme below.
If client authorization is disabled, the value here should be a fresh
x25519 pubkey that will remain unused.
@@ -1229,18 +1243,22 @@ Table of contents:
data of the right size (that's 8 bytes for 'client-id', 16 bytes for 'iv'
and 16 bytes for 'encrypted-cookie' all encoded with base64).
- When client authorization is enabled, each "auth-client" line contains
- the descriptor cookie encrypted to each individual client. We assume that
- each authorized client possesses a pre-shared x25519 keypair which is
- used to decrypt the descriptor cookie.
+ When client authorization is enabled, each "auth-client" line
+ contains the descriptor cookie `N_hs_desc_enc` encrypted to each
+ individual client. We assume that each authorized client possesses
+ a pre-shared x25519 keypair (`KP_hsc_desc_enc`) which is used to
+ decrypt the descriptor cookie.
We now describe the descriptor cookie encryption scheme. Here are the
relevant keys:
+ # KS/KP_hsc_desc_enc
client_x = private x25519 key of authorized client
client_X = public x25519 key of authorized client
+ # KS/KP_hss_desc_enc
hs_y = private key of ephemeral x25519 keypair of hidden service
hs_Y = public key of ephemeral x25519 keypair of hidden service
+ # N_hs_desc_enc
descriptor_cookie = descriptor cookie used to encrypt the descriptor
And here is what the hidden service computes:
--
To stop receiving notification emails like this one, please contact
the administrator of this repository.
_______________________________________________
tor-commits mailing list
tor-commits@xxxxxxxxxxxxxxxxxxxx
https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-commits