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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/unguessable_token.h"
#include <ostream>
#include <string_view>
#include "base/check.h"
#include "base/format_macros.h"
#include "base/rand_util.h"
#include "build/build_config.h"
#if !BUILDFLAG(IS_NACL)
#include "third_party/boringssl/src/include/openssl/mem.h"
#endif
namespace base {
UnguessableToken::UnguessableToken(const base::Token& token) : token_(token) {}
// static
UnguessableToken UnguessableToken::Create() {
Token token = Token::CreateRandom();
DCHECK(!token.is_zero());
return UnguessableToken(token);
}
// static
const UnguessableToken& UnguessableToken::Null() {
static const UnguessableToken null_token{};
return null_token;
}
// static
std::optional<UnguessableToken> UnguessableToken::Deserialize(uint64_t high,
uint64_t low) {
// Receiving a zeroed out UnguessableToken from another process means that it
// was never initialized via Create(). Since this method might also be used to
// create an UnguessableToken from data on disk, we will handle this case more
// gracefully since data could have been corrupted.
if (high == 0 && low == 0) {
return std::nullopt;
}
return UnguessableToken(Token{high, low});
}
// static
std::optional<UnguessableToken> UnguessableToken::DeserializeFromString(
std::string_view string_representation) {
auto token = Token::FromString(string_representation);
// A zeroed out token means that it's not initialized via Create().
if (!token.has_value() || token.value().is_zero()) {
return std::nullopt;
}
return UnguessableToken(token.value());
}
bool operator==(const UnguessableToken& lhs, const UnguessableToken& rhs) {
#if BUILDFLAG(IS_NACL)
// BoringSSL is unavailable for NaCl builds so it remains timing dependent.
return lhs.token_ == rhs.token_;
#else
auto bytes = lhs.token_.AsBytes();
auto other_bytes = rhs.token_.AsBytes();
return CRYPTO_memcmp(bytes.data(), other_bytes.data(), bytes.size()) == 0;
#endif
}
std::ostream& operator<<(std::ostream& out, const UnguessableToken& token) {
return out << "(" << token.ToString() << ")";
}
} // namespace base
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