1// Copyright (c) 2013 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef NET_QUIC_CRYPTO_CERT_COMPRESSOR_H_
6#define NET_QUIC_CRYPTO_CERT_COMPRESSOR_H_
7
8#include <string>
9#include <vector>
10
11#include "base/basictypes.h"
12#include "base/strings/string_piece.h"
13#include "net/base/net_export.h"
14#include "net/quic/crypto/common_cert_set.h"
15#include "net/quic/crypto/crypto_protocol.h"
16
17namespace net {
18
19// CertCompressor provides functions for compressing and decompressing
20// certificate chains using three techniquies:
21//   1) The peer may provide a list of a 64-bit, FNV-1a hashes of certificates
22//      that they already have. In the event that one of them is to be
23//      compressed, it can be replaced with just the hash.
24//   2) The peer may provide a number of hashes that represent sets of
25//      pre-shared certificates (CommonCertSets). If one of those certificates
26//      is to be compressed, and it's known to the given CommonCertSets, then it
27//      can be replaced with a set hash and certificate index.
28//   3) Otherwise the certificates are compressed with zlib using a pre-shared
29//      dictionary that consists of the certificates handled with the above
30//      methods and a small chunk of common substrings.
31class NET_EXPORT_PRIVATE CertCompressor {
32 public:
33  // CompressChain compresses the certificates in |certs| and returns a
34  // compressed representation. |common_sets| contains the common certificate
35  // sets known locally and |client_common_set_hashes| contains the hashes of
36  // the common sets known to the peer. |client_cached_cert_hashes| contains
37  // 64-bit, FNV-1a hashes of certificates that the peer already possesses.
38  static std::string CompressChain(const std::vector<std::string>& certs,
39                                   base::StringPiece client_common_set_hashes,
40                                   base::StringPiece client_cached_cert_hashes,
41                                   const CommonCertSets* common_sets);
42
43  // DecompressChain decompresses the result of |CompressChain|, given in |in|,
44  // into a series of certificates that are written to |out_certs|.
45  // |cached_certs| contains certificates that the peer may have omitted and
46  // |common_sets| contains the common certificate sets known locally.
47  static bool DecompressChain(base::StringPiece in,
48                              const std::vector<std::string>& cached_certs,
49                              const CommonCertSets* common_sets,
50                              std::vector<std::string>* out_certs);
51
52 private:
53  DISALLOW_COPY_AND_ASSIGN(CertCompressor);
54};
55
56}  // namespace net
57
58#endif  // NET_QUIC_CRYPTO_CERT_COMPRESSOR_H_
59