Switch to the new client-side phishing model that uses Murmurhash for word hashes.

chrome/common/safe_browsing/client_model.proto

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // This proto represents a machine learning model which is used to compute
 // the probability that a particular page visited by Chrome is phishing.
 //
 // Note: sine the machine learning model is trained on the server-side and then
 // downloaded onto the client it is important that this proto file stays in
 // sync with the server-side copy.  Otherwise, the client may not be able to
@@ skipping 42 matching lines @@
   }
 
   // List of rules which make up the model
   repeated Rule rule = 2;
 
   // List of indexes that point to the hashed page terms that appear in
   // the model.  The hashes are computed over page terms that are encoded
   // as lowercase UTF-8 strings.
   repeated int32 page_term = 3;
 
-  // List of indexes that point to the hashed page words.  The page words
-  // correspond to all words that appear in page terms.  If the term
-  // "one two" is in the list of page terms then "one" and "two" will be
-  // in the list of page words.
-  repeated int32 page_word = 4;
+  // List of hashed page words.  The page words correspond to all words that
+  // appear in page terms.  If the term "one two" is in the list of page terms
+  // then "one" and "two" will be in the list of page words.  For page words
+  // we don't use SHA256 because it is too expensive.  We use MurmurHash3
+  // instead.  See: http://code.google.com/p/smhasher.
+  repeated fixed32 page_word = 4;
 
   // Page terms in page_term contain at most this many page words.
   required int32 max_words_per_term = 5;
 
   // Model version number.  Every model that we train should have a different
   // version number and it should always be larger than the previous model
   // version.
   optional int32 version = 6;
 
   // List of known bad IP subnets.
   message IPSubnet {
     // The subnet prefix is a valid 16-byte IPv6 address (in network order) that
     // is hashed using sha256.
     required bytes prefix = 1;
 
     // Network prefix size in bits.  Default is an exact-host match.
     optional int32 size = 2 [default = 128];
   };
   repeated IPSubnet bad_subnet = 7;
+
+  // Murmur hash seed that was used to hash the page words.
+  optional fixed32 murmur_hash_seed = 8;
 }