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// Copyright (c) 2012 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.
#ifndef QUICHE_QUIC_CORE_CRYPTO_QUIC_DECRYPTER_H_
#define QUICHE_QUIC_CORE_CRYPTO_QUIC_DECRYPTER_H_
#include <cstddef>
#include <cstdint>
#include <memory>
#include <string>
#include "absl/strings/string_view.h"
#include "quiche/quic/core/crypto/quic_crypter.h"
#include "quiche/quic/core/quic_data_reader.h"
#include "quiche/quic/core/quic_packets.h"
#include "quiche/quic/platform/api/quic_export.h"
namespace quic {
class QUIC_EXPORT_PRIVATE QuicDecrypter : public QuicCrypter {
public:
virtual ~QuicDecrypter() {}
static std::unique_ptr<QuicDecrypter> Create(const ParsedQuicVersion& version,
QuicTag algorithm);
// Creates an IETF QuicDecrypter based on |cipher_suite| which must be an id
// returned by SSL_CIPHER_get_id. The caller is responsible for taking
// ownership of the new QuicDecrypter.
static std::unique_ptr<QuicDecrypter> CreateFromCipherSuite(
uint32_t cipher_suite);
// Sets the encryption key. Returns true on success, false on failure.
// |DecryptPacket| may not be called until |SetDiversificationNonce| is
// called and the preliminary keying material will be combined with that
// nonce in order to create the actual key and nonce-prefix.
//
// If this function is called, neither |SetKey| nor |SetNoncePrefix| may be
// called.
virtual bool SetPreliminaryKey(absl::string_view key) = 0;
// SetDiversificationNonce uses |nonce| to derive final keys based on the
// input keying material given by calling |SetPreliminaryKey|.
//
// Calling this function is a no-op if |SetPreliminaryKey| hasn't been
// called.
virtual bool SetDiversificationNonce(const DiversificationNonce& nonce) = 0;
// Populates |output| with the decrypted |ciphertext| and populates
// |output_length| with the length. Returns 0 if there is an error.
// |output| size is specified by |max_output_length| and must be
// at least as large as the ciphertext. |packet_number| is
// appended to the |nonce_prefix| value provided in SetNoncePrefix()
// to form the nonce.
// TODO(wtc): add a way for DecryptPacket to report decryption failure due
// to non-authentic inputs, as opposed to other reasons for failure.
virtual bool DecryptPacket(uint64_t packet_number,
absl::string_view associated_data,
absl::string_view ciphertext, char* output,
size_t* output_length,
size_t max_output_length) = 0;
// Reads a sample of ciphertext from |sample_reader| and uses the header
// protection key to generate a mask to use for header protection. If
// successful, this function returns this mask, which is at least 5 bytes
// long. Callers can detect failure by checking if the output string is empty.
virtual std::string GenerateHeaderProtectionMask(
QuicDataReader* sample_reader) = 0;
// The ID of the cipher. Return 0x03000000 ORed with the 'cryptographic suite
// selector'.
virtual uint32_t cipher_id() const = 0;
// Returns the maximum number of packets that can safely fail decryption with
// this decrypter.
virtual QuicPacketCount GetIntegrityLimit() const = 0;
// For use by unit tests only.
virtual absl::string_view GetKey() const = 0;
virtual absl::string_view GetNoncePrefix() const = 0;
static void DiversifyPreliminaryKey(absl::string_view preliminary_key,
absl::string_view nonce_prefix,
const DiversificationNonce& nonce,
size_t key_size, size_t nonce_prefix_size,
std::string* out_key,
std::string* out_nonce_prefix);
};
} // namespace quic
#endif // QUICHE_QUIC_CORE_CRYPTO_QUIC_DECRYPTER_H_
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