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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/platform/privacy_budget/identifiability_digest_helpers.h"
#include "third_party/blink/public/common/privacy_budget/identifiable_token_builder.h"
#include "third_party/blink/renderer/platform/wtf/shared_buffer.h"
#include "third_party/blink/renderer/platform/wtf/text/case_folding_hash.h"
#include "third_party/blink/renderer/platform/wtf/text/string_hash.h"
#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
namespace blink {
// Arbitrary value chosen to represent null strings.
constexpr uint64_t kNullStringDigest = 6554271438612835841L;
IdentifiableToken IdentifiabilityBenignStringToken(const String& in) {
if (in.IsNull())
return kNullStringDigest;
// Return the precomputed hash for the string. This makes this method O(1)
// instead of O(n), at the cost of only using the lower 32 bits of the hash.
return IdentifiableToken(WTF::GetHash(in));
}
IdentifiableToken IdentifiabilitySensitiveStringToken(const String& in) {
if (in.IsNull())
return IdentifiableToken(kNullStringDigest);
// Take the precomputed 32-bit hash, and xor the top and bottom halves to
// produce a 16-bit hash.
const uint32_t original_hash = WTF::GetHash(in);
return IdentifiableToken(((original_hash & 0xFFFF0000) >> 16) ^
(original_hash & 0xFFFF));
}
IdentifiableToken IdentifiabilityBenignCaseFoldingStringToken(
const String& in) {
if (in.IsNull())
return kNullStringDigest;
return IdentifiableToken(CaseFoldingHash::GetHash(in));
}
IdentifiableToken IdentifiabilitySensitiveCaseFoldingStringToken(
const String& in) {
if (in.IsNull())
return IdentifiableToken(kNullStringDigest);
// Take the 32-bit hash, and xor the top and bottom halves to produce a 16-bit
// hash.
const uint32_t original_hash = CaseFoldingHash::GetHash(in);
return IdentifiableToken(((original_hash & 0xFFFF0000) >> 16) ^
(original_hash & 0xFFFF));
}
IdentifiableToken IdentifiabilityBenignStringVectorToken(
const Vector<String>& in) {
IdentifiableTokenBuilder builder;
builder.AddValue(in.size());
for (const String& elem : in) {
builder.AddToken(IdentifiabilityBenignStringToken(elem));
}
return builder.GetToken();
}
} // namespace blink
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