[tor-commits] [stem/master] Move get_subcredential() into HiddenServiceDescriptorV3

[atagar at torproject.org]

commit 1a7040063df5cd4ec030f3498ea3601e44e92e69
Author: Damian Johnson <atagar at torproject.org>
Date:   Tue Oct 15 13:46:15 2019 -0700

    Move get_subcredential() into HiddenServiceDescriptorV3
    
    I'm not entirely sure yet if we need a helper for this, but for the moment
    moving it alongside _public_key_from_address().
---
 stem/descriptor/hidden_service.py | 13 ++++++++++---
 stem/descriptor/hsv3_crypto.py    | 18 ------------------
 2 files changed, 10 insertions(+), 21 deletions(-)

diff --git a/stem/descriptor/hidden_service.py b/stem/descriptor/hidden_service.py
index 9885fe7a..daae516b 100644
--- a/stem/descriptor/hidden_service.py
+++ b/stem/descriptor/hidden_service.py
@@ -1003,7 +1003,7 @@ class HiddenServiceDescriptorV3(BaseHiddenServiceDescriptor):
 
     # Get the main encrypted descriptor body
     revision_counter_int = int(time.time())
-    subcredential = hsv3_crypto.get_subcredential(public_identity_key_bytes, blinded_pubkey_bytes)
+    subcredential = HiddenServiceDescriptorV3._subcredential(public_identity_key_bytes, blinded_pubkey_bytes)
 
     # XXX It would be more elegant to have all the above variables attached to
     # this descriptor object so that we don't have to carry them around
@@ -1099,8 +1099,7 @@ class HiddenServiceDescriptorV3(BaseHiddenServiceDescriptor):
         raise ValueError('No signing key is present')
 
       identity_public_key = HiddenServiceDescriptorV3._public_key_from_address(onion_address)
-
-      subcredential = hsv3_crypto.get_subcredential(identity_public_key, blinded_key)
+      subcredential = HiddenServiceDescriptorV3._subcredential(identity_public_key, blinded_key)
 
       outer_layer = OuterLayer._decrypt(self.superencrypted, self.revision_counter, subcredential, blinded_key)
       self._inner_layer = InnerLayer._decrypt(outer_layer, self.revision_counter, subcredential, blinded_key)
@@ -1136,6 +1135,14 @@ class HiddenServiceDescriptorV3(BaseHiddenServiceDescriptor):
 
     return pubkey
 
+  @staticmethod
+  def _subcredential(public_key, blinded_key):
+    # credential = H('credential' | public-identity-key)
+    # subcredential = H('subcredential' | credential | blinded-public-key)
+
+    credential = hashlib.sha3_256(b'credential%s' % public_key).digest()
+    return hashlib.sha3_256(b'subcredential%s%s' % (credential, blinded_key)).digest()
+
 
 class OuterLayer(Descriptor):
   """
diff --git a/stem/descriptor/hsv3_crypto.py b/stem/descriptor/hsv3_crypto.py
index 71f76e9c..2b99f030 100644
--- a/stem/descriptor/hsv3_crypto.py
+++ b/stem/descriptor/hsv3_crypto.py
@@ -75,24 +75,6 @@ class HSv3PublicBlindedKey(object):
 
 
 """
-subcredential
-
-       subcredential = H("subcredential" | credential | blinded-public-ke
-       credential = H("credential" | public-identity-key)
-"""
-
-
-def get_subcredential(public_identity_key, blinded_key):
-  cred_bytes_constant = 'credential'.encode()
-  subcred_bytes_constant = 'subcredential'.encode()
-
-  credential = hashlib.sha3_256(b'%s%s' % (cred_bytes_constant, public_identity_key)).digest()
-  subcredential = hashlib.sha3_256(b'%s%s%s' % (subcred_bytes_constant, credential, blinded_key)).digest()
-
-  return subcredential
-
-
-"""
 Onion address
 
      onion_address = base32(PUBKEY | CHECKSUM | VERSION) + ".onion"