Modify rappor parameters.

components/rappor/byte_vector_utils.cc

 // Copyright 2014 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.
 
 #include "components/rappor/byte_vector_utils.h"
 
 #include <string>
 
 #include "base/logging.h"
 #include "base/rand_util.h"
@@ skipping 60 matching lines @@
     return true;
   // 4. K = HMAC(K, V || 0x01 || provided_data)
   if (!HMAC_Rotate(*hmac2, Concat(*value, 0x01, provided_data), out_hmac))
     return false;
   // 5. V = HMAC(K, V)
   return HMAC_Rehash(*out_hmac, value);
 }
 
 }  // namespace
 
+ByteVector* ByteVectorAnd(const ByteVector& lhs, ByteVector* rhs) {
+  DCHECK_EQ(lhs.size(), rhs->size());
+  for (size_t i = 0; i < lhs.size(); ++i) {
+    (*rhs)[i] = lhs[i] & (*rhs)[i];
+  }
+  return rhs;
+}
+
 ByteVector* ByteVectorOr(const ByteVector& lhs, ByteVector* rhs) {
   DCHECK_EQ(lhs.size(), rhs->size());
-  for (size_t i = 0, len = lhs.size(); i < len; ++i) {
+  for (size_t i = 0; i < lhs.size(); ++i) {
     (*rhs)[i] = lhs[i] | (*rhs)[i];
   }
   return rhs;
 }
 
 ByteVector* ByteVectorMerge(const ByteVector& mask,
                             const ByteVector& lhs,
                             ByteVector* rhs) {
   DCHECK_EQ(lhs.size(), rhs->size());
-  for (size_t i = 0, len = lhs.size(); i < len; ++i) {
+  for (size_t i = 0; i < lhs.size(); ++i) {
     (*rhs)[i] = (lhs[i] & ~mask[i]) | ((*rhs)[i] & mask[i]);
   }
   return rhs;
 }
 
 int CountBits(const ByteVector& vector) {
   int bit_count = 0;
   for (size_t i = 0; i < vector.size(); ++i) {
     uint8_t byte = vector[i];
     for (int j = 0; j < 8 ; ++j) {
@@ skipping 16 matching lines @@
 }
 
 ByteVector ByteVectorGenerator::GetWeightedRandomByteVector(
     Probability probability) {
   ByteVector bytes = GetRandomByteVector();
   switch (probability) {
     case PROBABILITY_75:
       return *ByteVectorOr(GetRandomByteVector(), &bytes);
     case PROBABILITY_50:
       return bytes;
+    case PROBABILITY_25:
+      return *ByteVectorAnd(GetRandomByteVector(), &bytes);
   }
   NOTREACHED();
   return bytes;
 }
 
 HmacByteVectorGenerator::HmacByteVectorGenerator(
     size_t byte_count,
     const std::string& entropy_input,
     const std::string& personalization_string)
     : ByteVectorGenerator(byte_count),
@@ skipping 66 matching lines @@
     bytes_to_go -= n;
     generated_bytes_ += n;
     // Check max_number_of_bits_per_request from 10.1 Table 2
     // max_number_of_bits_per_request == 2^19 bits == 2^16 bytes
     DCHECK_LT(generated_bytes_, 1U << 16);
   }
   return bytes;
 }
 
 }  // namespace rappor