[tor-commits] [stem/master] Drop get_subcredential() helper

[atagar at torproject.org]

commit 1402f448dd60cfebccee81d574b56afe46aa2b5e
Author: Damian Johnson <atagar at torproject.org>
Date:   Wed Oct 2 14:42:53 2019 -0700

    Drop get_subcredential() helper
    
    This particular helper is just an alias for two lines. Too small to add
    clarity.
---
 stem/descriptor/hidden_service.py | 15 ++++++++++-----
 stem/descriptor/hsv3_crypto.py    | 20 --------------------
 2 files changed, 10 insertions(+), 25 deletions(-)

diff --git a/stem/descriptor/hidden_service.py b/stem/descriptor/hidden_service.py
index 29fc838a..dc282202 100644
--- a/stem/descriptor/hidden_service.py
+++ b/stem/descriptor/hidden_service.py
@@ -566,23 +566,28 @@ class HiddenServiceDescriptorV3(BaseHiddenServiceDescriptor):
 
     for extension in desc_signing_cert.extensions:
       if extension.type == ExtensionType.HAS_SIGNING_KEY:
-        blinded_key_bytes = extension.data
+        blinded_key = extension.data
         break
 
-    if not blinded_key_bytes:
+    if not blinded_key:
       raise ValueError('No signing key extension present')
 
     identity_public_key = HiddenServiceDescriptorV3._public_key_from_address(onion_address)
-    subcredential_bytes = stem.descriptor.hsv3_crypto.get_subcredential(identity_public_key, blinded_key_bytes)
 
-    outter_layer_plaintext = stem.descriptor.hsv3_crypto.decrypt_outter_layer(self.superencrypted, self.revision_counter, identity_public_key, blinded_key_bytes, subcredential_bytes)
+    # credential = H('credential' | public-identity-key)
+    # subcredential = H('subcredential' | credential | blinded-public-key)
+
+    credential = hashlib.sha3_256(b'credential%s' % (identity_public_key)).digest()
+    subcredential = hashlib.sha3_256(b'subcredential%s%s' % (credential, blinded_key)).digest()
+
+    outter_layer_plaintext = stem.descriptor.hsv3_crypto.decrypt_outter_layer(self.superencrypted, self.revision_counter, identity_public_key, blinded_key, subcredential)
 
     if outer_layer:
       return outter_layer_plaintext
 
     inner_layer_ciphertext = stem.descriptor.hsv3_crypto.parse_superencrypted_plaintext(outter_layer_plaintext)
 
-    inner_layer_plaintext = stem.descriptor.hsv3_crypto.decrypt_inner_layer(inner_layer_ciphertext, self.revision_counter, identity_public_key, blinded_key_bytes, subcredential_bytes)
+    inner_layer_plaintext = stem.descriptor.hsv3_crypto.decrypt_inner_layer(inner_layer_ciphertext, self.revision_counter, identity_public_key, blinded_key, subcredential)
 
     return inner_layer_plaintext
 
diff --git a/stem/descriptor/hsv3_crypto.py b/stem/descriptor/hsv3_crypto.py
index e6e8c03e..2f9f2d66 100644
--- a/stem/descriptor/hsv3_crypto.py
+++ b/stem/descriptor/hsv3_crypto.py
@@ -27,26 +27,6 @@ Blinded key stuff
 pass
 
 """
-Subcredential:
-
-  subcredential = H('subcredential' | credential | blinded-public-key
-  credential = H('credential' | public-identity-key)
-
-Both keys are in bytes
-"""
-
-
-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
-
-
-"""
 Basic descriptor logic:
 
   SALT = 16 bytes from H(random), changes each time we rebuld the