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| 1 // Copyright 2014 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 #include "net/cert/ct_ev_whitelist.h" |
| 6 |
| 7 #include <set> |
| 8 |
| 9 #include "base/big_endian.h" |
| 10 #include "base/file_util.h" |
| 11 #include "base/lazy_instance.h" |
| 12 #include "base/logging.h" |
| 13 |
| 14 namespace net { |
| 15 |
| 16 namespace ct { |
| 17 |
| 18 namespace { |
| 19 base::LazyInstance<std::set<std::string> >::Leaky g_current_ev_whitelist = |
| 20 LAZY_INSTANCE_INITIALIZER; |
| 21 |
| 22 const uint8 kCertHashLengthBits = 64; // 8 bytes |
| 23 const uint64 kGolombMParameterBits = 47; // 2^47 |
| 24 } // namespace |
| 25 |
| 26 namespace internal { |
| 27 |
| 28 BitStreamReader::BitStreamReader(const char* source, size_t length) |
| 29 : source_(source), length_(length), current_byte_(0), current_bit_(7) { |
| 30 } |
| 31 |
| 32 bool BitStreamReader::ReadUnaryEncoding(uint64* out) { |
| 33 uint64 res = 0; |
| 34 if (BitsLeft() == 0) |
| 35 return false; |
| 36 |
| 37 while ((BitsLeft() > 0) && ReadBit()) |
| 38 res++; |
| 39 |
| 40 *out = res; |
| 41 return true; |
| 42 } |
| 43 |
| 44 bool BitStreamReader::ReadBits(uint8 num_bits, uint64* out) { |
| 45 if (num_bits > 64) |
| 46 return false; |
| 47 |
| 48 if (BitsLeft() < num_bits) |
| 49 return false; |
| 50 |
| 51 uint64 res = 0; |
| 52 for (uint8 i = 0; i < num_bits; ++i) |
| 53 res |= (static_cast<uint64>(ReadBit()) << (num_bits - (i + 1))); |
| 54 |
| 55 *out = res; |
| 56 return true; |
| 57 } |
| 58 |
| 59 uint64 BitStreamReader::BitsLeft() const { |
| 60 if (current_byte_ == length_) |
| 61 return 0; |
| 62 return (length_ - (current_byte_ + 1)) * 8 + current_bit_ + 1; |
| 63 } |
| 64 |
| 65 uint8 BitStreamReader::ReadBit() { |
| 66 DCHECK_GT(BitsLeft(), 0u); |
| 67 DCHECK(current_bit_ < 8 && current_bit_ >= 0); |
| 68 uint8 res = (source_[current_byte_] & (1 << current_bit_)) >> current_bit_; |
| 69 current_bit_--; |
| 70 if (current_bit_ < 0) { |
| 71 current_byte_++; |
| 72 current_bit_ = 7; |
| 73 } |
| 74 |
| 75 return res; |
| 76 } |
| 77 |
| 78 bool UncompressEVWhitelist(const std::string& compressed_whitelist, |
| 79 std::set<std::string>* uncompressed_list) { |
| 80 BitStreamReader reader(compressed_whitelist.data(), |
| 81 compressed_whitelist.size()); |
| 82 std::set<std::string> result; |
| 83 |
| 84 VLOG(1) << "Uncompressing EV whitelist of size " |
| 85 << compressed_whitelist.size(); |
| 86 uint64 curr_hash(0); |
| 87 if (!reader.ReadBits(kCertHashLengthBits, &curr_hash)) { |
| 88 VLOG(1) << "Failed reading first hash."; |
| 89 return false; |
| 90 } |
| 91 char hash_bytes[8]; |
| 92 base::WriteBigEndian(hash_bytes, curr_hash); |
| 93 result.insert(std::string(hash_bytes, 8)); |
| 94 static const uint64 M = static_cast<uint64>(1) << kGolombMParameterBits; |
| 95 |
| 96 while (reader.BitsLeft() > kGolombMParameterBits) { |
| 97 uint64 read_prefix = 0; |
| 98 if (!reader.ReadUnaryEncoding(&read_prefix)) { |
| 99 VLOG(1) << "Failed reading unary-encoded prefix."; |
| 100 return false; |
| 101 } |
| 102 |
| 103 uint64 r = 0; |
| 104 if (!reader.ReadBits(kGolombMParameterBits, &r)) { |
| 105 VLOG(1) << "Failed reading " << kGolombMParameterBits << " bits."; |
| 106 return false; |
| 107 } |
| 108 |
| 109 uint64 curr_diff = read_prefix * M + r; |
| 110 curr_hash += curr_diff; |
| 111 |
| 112 base::WriteBigEndian(hash_bytes, curr_hash); |
| 113 result.insert(std::string(hash_bytes, 8)); |
| 114 } |
| 115 |
| 116 uncompressed_list->swap(result); |
| 117 return true; |
| 118 } |
| 119 |
| 120 void SetEVWhitelistData(std::set<std::string>& ev_whitelist) { |
| 121 g_current_ev_whitelist.Get().swap(ev_whitelist); |
| 122 } |
| 123 |
| 124 } // namespace internal |
| 125 |
| 126 void SetEVWhitelistFromFile(const base::FilePath& compressed_whitelist_file) { |
| 127 VLOG(1) << "Setting EV whitelist from file: " |
| 128 << compressed_whitelist_file.value(); |
| 129 std::string compressed_list; |
| 130 if (!base::ReadFileToString(compressed_whitelist_file, &compressed_list)) { |
| 131 VLOG(1) << "Failed reading from " << compressed_whitelist_file.value(); |
| 132 return; |
| 133 } |
| 134 |
| 135 std::set<std::string> uncompressed_list; |
| 136 if (!internal::UncompressEVWhitelist(compressed_list, &uncompressed_list)) { |
| 137 VLOG(1) << "Failed uncompressing."; |
| 138 return; |
| 139 } |
| 140 VLOG(1) << "Uncompressing succeeded, hashes: " << uncompressed_list.size(); |
| 141 |
| 142 internal::SetEVWhitelistData(uncompressed_list); |
| 143 } |
| 144 |
| 145 bool IsCertificateHashInWhitelist(const std::string& certificate_hash) { |
| 146 const std::set<std::string>& current_ev_whitelist = |
| 147 g_current_ev_whitelist.Get(); |
| 148 return current_ev_whitelist.find(certificate_hash) != |
| 149 current_ev_whitelist.end(); |
| 150 } |
| 151 |
| 152 bool HasValidEVWhitelist() { |
| 153 return !g_current_ev_whitelist.Get().empty(); |
| 154 } |
| 155 |
| 156 } // namespace ct |
| 157 |
| 158 } // namespace net |
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