oox/source/crypto/Standard2007Engine.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  */
  10
  11 #include <oox/crypto/Standard2007Engine.hxx>
  12
  13 #include <oox/crypto/CryptTools.hxx>
  14 #include <oox/helper/binaryinputstream.hxx>
  15 #include <oox/helper/binaryoutputstream.hxx>
  16 #include <rtl/random.h>
  17
  18 #include <comphelper/hash.hxx>
  19
  20 namespace oox::crypto {
  21
  22 /* =========================================================================== */
  23 /*  Kudos to Caolan McNamara who provided the core decryption implementations. */
  24 /* =========================================================================== */
  25 namespace
  26 {
  27
  28 void lclRandomGenerateValues(sal_uInt8* aArray, sal_uInt32 aSize)
  29 {
  30     rtlRandomPool aRandomPool = rtl_random_createPool();
  31     rtl_random_getBytes(aRandomPool, aArray, aSize);
  32     rtl_random_destroyPool(aRandomPool);
  33 }
  34
  35 constexpr OUStringLiteral lclCspName = u"Microsoft Enhanced RSA and AES Cryptographic Provider";
  36 constexpr const sal_uInt32 AES128Size = 16;
  37
  38 } // end anonymous namespace
  39
  40 bool Standard2007Engine::generateVerifier()
  41 {
  42     // only support key of size 128 bit (16 byte)
  43     if (mKey.size() != 16)
  44         return false;
  45
  46     std::vector<sal_uInt8> verifier(msfilter::ENCRYPTED_VERIFIER_LENGTH);
  47     std::vector<sal_uInt8> encryptedVerifier(msfilter::ENCRYPTED_VERIFIER_LENGTH);
  48
  49     lclRandomGenerateValues(verifier.data(), verifier.size());
  50
  51     std::vector<sal_uInt8> iv;
  52     Encrypt aEncryptorVerifier(mKey, iv, Crypto::AES_128_ECB);
  53     if (aEncryptorVerifier.update(encryptedVerifier, verifier) != msfilter::ENCRYPTED_VERIFIER_LENGTH)
  54         return false;
  55     std::copy(encryptedVerifier.begin(), encryptedVerifier.end(), mInfo.verifier.encryptedVerifier);
  56
  57     mInfo.verifier.encryptedVerifierHashSize = comphelper::SHA1_HASH_LENGTH;
  58     std::vector<sal_uInt8> hash = comphelper::Hash::calculateHash(verifier.data(), verifier.size(), comphelper::HashType::SHA1);
  59     hash.resize(comphelper::SHA256_HASH_LENGTH, 0);
  60
  61     std::vector<sal_uInt8> encryptedHash(comphelper::SHA256_HASH_LENGTH, 0);
  62
  63     Encrypt aEncryptorHash(mKey, iv, Crypto::AES_128_ECB);
  64     aEncryptorHash.update(encryptedHash, hash, hash.size());
  65     std::copy(encryptedHash.begin(), encryptedHash.end(), mInfo.verifier.encryptedVerifierHash);
  66
  67     return true;
  68 }
  69
  70 bool Standard2007Engine::calculateEncryptionKey(std::u16string_view rPassword)
  71 {
  72     sal_uInt32 saltSize = mInfo.verifier.saltSize;
  73     size_t passwordByteLength = rPassword.size() * 2;
  74     const sal_uInt8* saltArray = mInfo.verifier.salt;
  75
  76     // Prepare initial data -> salt + password (in 16-bit chars)
  77     std::vector<sal_uInt8> initialData(saltSize + passwordByteLength);
  78     std::copy(saltArray, saltArray + saltSize, initialData.begin());
  79
  80     auto p = initialData.begin() + saltSize;
  81     for (size_t i = 0; i != rPassword.size(); ++i) {
  82         auto c = rPassword[i];
  83         *p++ = c & 0xFF;
  84         *p++ = c >> 8;
  85     }
  86
  87     // use "hash" vector for result of sha1 hashing
  88     // calculate SHA1 hash of initialData
  89     std::vector<sal_uInt8> hash = comphelper::Hash::calculateHash(initialData.data(), initialData.size(), comphelper::HashType::SHA1);
  90
  91     // data = iterator (4bytes) + hash
  92     std::vector<sal_uInt8> data(comphelper::SHA1_HASH_LENGTH + 4, 0);
  93
  94     for (sal_Int32 i = 0; i < 50000; ++i)
  95     {
  96         ByteOrderConverter::writeLittleEndian(data.data(), i);
  97         std::copy(hash.begin(), hash.end(), data.begin() + 4);
  98         hash = comphelper::Hash::calculateHash(data.data(), data.size(), comphelper::HashType::SHA1);
  99     }
 100     std::copy(hash.begin(), hash.end(), data.begin() );
 101     std::fill(data.begin() + comphelper::SHA1_HASH_LENGTH, data.end(), 0 );
 102
 103     hash = comphelper::Hash::calculateHash(data.data(), data.size(), comphelper::HashType::SHA1);
 104
 105     // derive key
 106     std::vector<sal_uInt8> buffer(64, 0x36);
 107     for (size_t i = 0; i < hash.size(); ++i)
 108         buffer[i] ^= hash[i];
 109
 110     hash = comphelper::Hash::calculateHash(buffer.data(), buffer.size(), comphelper::HashType::SHA1);
 111     if (mKey.size() > hash.size())
 112         return false;
 113     std::copy(hash.begin(), hash.begin() + mKey.size(), mKey.begin());
 114
 115     return true;
 116 }
 117
 118 bool Standard2007Engine::generateEncryptionKey(const OUString& password)
 119 {
 120     mKey.clear();
 121     /*
 122         KeySize (4 bytes): An unsigned integer that specifies the number of bits in the encryption key.
 123         MUST be a multiple of 8. MUST be one of the values in the following table:
 124         Algorithm   Value                               Comment
 125         Any         0x00000000                          Determined by Flags
 126         RC4         0x00000028 – 0x00000080             (inclusive) 8-bit increments.
 127         AES         0x00000080, 0x000000C0, 0x00000100  128, 192 or 256-bit
 128     */
 129     if (mInfo.header.keyBits > 8192) // should we strictly enforce the above 256 bit limit ?
 130         return false;
 131     mKey.resize(mInfo.header.keyBits / 8, 0);
 132     if (mKey.empty())
 133         return false;
 134
 135     calculateEncryptionKey(password);
 136
 137     std::vector<sal_uInt8> encryptedVerifier(msfilter::ENCRYPTED_VERIFIER_LENGTH);
 138     std::copy(
 139         mInfo.verifier.encryptedVerifier,
 140         mInfo.verifier.encryptedVerifier + msfilter::ENCRYPTED_VERIFIER_LENGTH,
 141         encryptedVerifier.begin());
 142
 143     std::vector<sal_uInt8> encryptedHash(comphelper::SHA256_HASH_LENGTH);
 144     std::copy(
 145         mInfo.verifier.encryptedVerifierHash,
 146         mInfo.verifier.encryptedVerifierHash + comphelper::SHA256_HASH_LENGTH,
 147         encryptedHash.begin());
 148
 149     std::vector<sal_uInt8> verifier(encryptedVerifier.size(), 0);
 150     Decrypt::aes128ecb(verifier, encryptedVerifier, mKey);
 151
 152     std::vector<sal_uInt8> verifierHash(encryptedHash.size(), 0);
 153     Decrypt::aes128ecb(verifierHash, encryptedHash, mKey);
 154
 155     std::vector<sal_uInt8> hash = comphelper::Hash::calculateHash(verifier.data(), verifier.size(), comphelper::HashType::SHA1);
 156
 157     return std::equal(hash.begin(), hash.end(), verifierHash.begin());
 158 }
 159
 160 bool Standard2007Engine::decrypt(BinaryXInputStream& aInputStream,
 161                                  BinaryXOutputStream& aOutputStream)
 162 {
 163     sal_uInt32 totalSize = aInputStream.readuInt32(); // Document unencrypted size - 4 bytes
 164     aInputStream.skip(4); // Reserved 4 Bytes
 165
 166     std::vector<sal_uInt8> iv;
 167     Decrypt aDecryptor(mKey, iv, Crypto::AES_128_ECB);
 168     std::vector<sal_uInt8> inputBuffer (4096);
 169     std::vector<sal_uInt8> outputBuffer(4096);
 170     sal_uInt32 inputLength;
 171     sal_uInt32 outputLength;
 172     sal_uInt32 remaining = totalSize;
 173
 174     while ((inputLength = aInputStream.readMemory(inputBuffer.data(), inputBuffer.size())) > 0)
 175     {
 176         outputLength = aDecryptor.update(outputBuffer, inputBuffer, inputLength);
 177         sal_uInt32 writeLength = std::min(outputLength, remaining);
 178         aOutputStream.writeMemory(outputBuffer.data(), writeLength);
 179         remaining -= outputLength;
 180     }
 181     return true;
 182 }
 183
 184 bool Standard2007Engine::checkDataIntegrity()
 185 {
 186     return true;
 187 }
 188
 189 bool Standard2007Engine::setupEncryption(OUString const & password)
 190 {
 191     mInfo.header.flags        = msfilter::ENCRYPTINFO_AES | msfilter::ENCRYPTINFO_CRYPTOAPI;
 192     mInfo.header.algId        = msfilter::ENCRYPT_ALGO_AES128;
 193     mInfo.header.algIdHash    = msfilter::ENCRYPT_HASH_SHA1;
 194     mInfo.header.keyBits      = msfilter::ENCRYPT_KEY_SIZE_AES_128;
 195     mInfo.header.providedType = msfilter::ENCRYPT_PROVIDER_TYPE_AES;
 196
 197     lclRandomGenerateValues(mInfo.verifier.salt, mInfo.verifier.saltSize);
 198     const sal_Int32 keyLength = mInfo.header.keyBits / 8;
 199
 200     mKey.clear();
 201     mKey.resize(keyLength, 0);
 202
 203     if (!calculateEncryptionKey(password))
 204         return false;
 205
 206     if (!generateVerifier())
 207         return false;
 208
 209     return true;
 210 }
 211
 212 void Standard2007Engine::writeEncryptionInfo(BinaryXOutputStream& rStream)
 213 {
 214     rStream.WriteUInt32(msfilter::VERSION_INFO_2007_FORMAT);
 215
 216     sal_uInt32 cspNameSize = (lclCspName.getLength() * 2) + 2;
 217
 218     sal_uInt32 encryptionHeaderSize = static_cast<sal_uInt32>(sizeof(msfilter::EncryptionStandardHeader));
 219
 220     rStream.WriteUInt32(mInfo.header.flags);
 221     sal_uInt32 headerSize = encryptionHeaderSize + cspNameSize;
 222     rStream.WriteUInt32(headerSize);
 223
 224     rStream.WriteUInt32(mInfo.header.flags);
 225     rStream.WriteUInt32(mInfo.header.sizeExtra);
 226     rStream.WriteUInt32(mInfo.header.algId);
 227     rStream.WriteUInt32(mInfo.header.algIdHash);
 228     rStream.WriteUInt32(mInfo.header.keyBits);
 229     rStream.WriteUInt32(mInfo.header.providedType);
 230     rStream.WriteUInt32(mInfo.header.reserved1);
 231     rStream.WriteUInt32(mInfo.header.reserved2);
 232     rStream.writeUnicodeArray(lclCspName);
 233     rStream.WriteUInt16(0);
 234
 235     rStream.WriteUInt32(mInfo.verifier.saltSize);
 236     rStream.writeMemory(&mInfo.verifier.salt, sizeof mInfo.verifier.salt);
 237     rStream.writeMemory(&mInfo.verifier.encryptedVerifier, sizeof mInfo.verifier.encryptedVerifier);
 238     rStream.WriteUInt32(mInfo.verifier.encryptedVerifierHashSize);
 239     rStream.writeMemory(
 240         &mInfo.verifier.encryptedVerifierHash, sizeof mInfo.verifier.encryptedVerifierHash);
 241 }
 242
 243 void Standard2007Engine::encrypt(const css::uno::Reference<css::io::XInputStream> &  rxInputStream,
 244                                  css::uno::Reference<css::io::XOutputStream> & rxOutputStream,
 245                                  sal_uInt32 nSize)
 246 {
 247     if (mKey.empty())
 248         return;
 249
 250     BinaryXOutputStream aBinaryOutputStream(rxOutputStream, false);
 251     BinaryXInputStream aBinaryInputStream(rxInputStream, false);
 252
 253     aBinaryOutputStream.WriteUInt32(nSize); // size
 254     aBinaryOutputStream.WriteUInt32(0U);    // reserved
 255
 256     std::vector<sal_uInt8> inputBuffer(1024);
 257     std::vector<sal_uInt8> outputBuffer(1024);
 258
 259     sal_uInt32 inputLength;
 260     sal_uInt32 outputLength;
 261
 262     std::vector<sal_uInt8> iv;
 263     Encrypt aEncryptor(mKey, iv, Crypto::AES_128_ECB);
 264
 265     while ((inputLength = aBinaryInputStream.readMemory(inputBuffer.data(), inputBuffer.size())) > 0)
 266     {
 267         // increase size to multiple of 16 (size of mKey) if necessary
 268         inputLength = inputLength % AES128Size == 0 ?
 269                             inputLength : roundUp(inputLength, AES128Size);
 270         outputLength = aEncryptor.update(outputBuffer, inputBuffer, inputLength);
 271         aBinaryOutputStream.writeMemory(outputBuffer.data(), outputLength);
 272     }
 273 }
 274
 275 bool Standard2007Engine::readEncryptionInfo(css::uno::Reference<css::io::XInputStream> & rxInputStream)
 276 {
 277     BinaryXInputStream aBinaryStream(rxInputStream, false);
 278
 279     mInfo.header.flags = aBinaryStream.readuInt32();
 280     if (getFlag(mInfo.header.flags, msfilter::ENCRYPTINFO_EXTERNAL))
 281         return false;
 282
 283     sal_uInt32 nHeaderSize = aBinaryStream.readuInt32();
 284
 285     sal_uInt32 actualHeaderSize = sizeof(mInfo.header);
 286
 287     if (nHeaderSize < actualHeaderSize)
 288         return false;
 289
 290     mInfo.header.flags = aBinaryStream.readuInt32();
 291     mInfo.header.sizeExtra = aBinaryStream.readuInt32();
 292     mInfo.header.algId = aBinaryStream.readuInt32();
 293     mInfo.header.algIdHash = aBinaryStream.readuInt32();
 294     mInfo.header.keyBits = aBinaryStream.readuInt32();
 295     mInfo.header.providedType = aBinaryStream.readuInt32();
 296     mInfo.header.reserved1 = aBinaryStream.readuInt32();
 297     mInfo.header.reserved2 = aBinaryStream.readuInt32();
 298
 299     aBinaryStream.skip(nHeaderSize - actualHeaderSize);
 300
 301     mInfo.verifier.saltSize = aBinaryStream.readuInt32();
 302     aBinaryStream.readArray(mInfo.verifier.salt, SAL_N_ELEMENTS(mInfo.verifier.salt));
 303     aBinaryStream.readArray(mInfo.verifier.encryptedVerifier, SAL_N_ELEMENTS(mInfo.verifier.encryptedVerifier));
 304     mInfo.verifier.encryptedVerifierHashSize = aBinaryStream.readuInt32();
 305     aBinaryStream.readArray(mInfo.verifier.encryptedVerifierHash, SAL_N_ELEMENTS(mInfo.verifier.encryptedVerifierHash));
 306
 307     if (mInfo.verifier.saltSize != 16)
 308         return false;
 309
 310     // check flags and algorithm IDs, required are AES128 and SHA-1
 311     if (!getFlag(mInfo.header.flags, msfilter::ENCRYPTINFO_CRYPTOAPI))
 312         return false;
 313
 314     if (!getFlag(mInfo.header.flags, msfilter::ENCRYPTINFO_AES))
 315         return false;
 316
 317     // algorithm ID 0 defaults to AES128 too, if ENCRYPTINFO_AES flag is set
 318     if (mInfo.header.algId != 0 && mInfo.header.algId != msfilter::ENCRYPT_ALGO_AES128)
 319         return false;
 320
 321     // hash algorithm ID 0 defaults to SHA-1 too
 322     if (mInfo.header.algIdHash != 0 && mInfo.header.algIdHash != msfilter::ENCRYPT_HASH_SHA1)
 323         return false;
 324
 325     if (mInfo.verifier.encryptedVerifierHashSize != 20)
 326         return false;
 327
 328     return !aBinaryStream.isEof();
 329 }
 330
 331 } // namespace oox::crypto
 332
 333 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */