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| 1 // Copyright (c) 2011 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 "crypto/rsa_private_key.h" |
| 6 |
| 7 #include <algorithm> |
| 8 #include <list> |
| 9 |
| 10 #include "base/logging.h" |
| 11 #include "base/memory/scoped_ptr.h" |
| 12 #include "base/strings/string_util.h" |
| 13 |
| 14 // This file manually encodes and decodes RSA private keys using PrivateKeyInfo |
| 15 // from PKCS #8 and RSAPrivateKey from PKCS #1. These structures are: |
| 16 // |
| 17 // PrivateKeyInfo ::= SEQUENCE { |
| 18 // version Version, |
| 19 // privateKeyAlgorithm PrivateKeyAlgorithmIdentifier, |
| 20 // privateKey PrivateKey, |
| 21 // attributes [0] IMPLICIT Attributes OPTIONAL |
| 22 // } |
| 23 // |
| 24 // RSAPrivateKey ::= SEQUENCE { |
| 25 // version Version, |
| 26 // modulus INTEGER, |
| 27 // publicExponent INTEGER, |
| 28 // privateExponent INTEGER, |
| 29 // prime1 INTEGER, |
| 30 // prime2 INTEGER, |
| 31 // exponent1 INTEGER, |
| 32 // exponent2 INTEGER, |
| 33 // coefficient INTEGER |
| 34 // } |
| 35 |
| 36 namespace { |
| 37 // Helper for error handling during key import. |
| 38 #define READ_ASSERT(truth) \ |
| 39 if (!(truth)) { \ |
| 40 NOTREACHED(); \ |
| 41 return false; \ |
| 42 } |
| 43 } // namespace |
| 44 |
| 45 namespace crypto { |
| 46 |
| 47 const uint8 PrivateKeyInfoCodec::kRsaAlgorithmIdentifier[] = { |
| 48 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, |
| 49 0x05, 0x00 |
| 50 }; |
| 51 |
| 52 PrivateKeyInfoCodec::PrivateKeyInfoCodec(bool big_endian) |
| 53 : big_endian_(big_endian) {} |
| 54 |
| 55 PrivateKeyInfoCodec::~PrivateKeyInfoCodec() {} |
| 56 |
| 57 bool PrivateKeyInfoCodec::Export(std::vector<uint8>* output) { |
| 58 std::list<uint8> content; |
| 59 |
| 60 // Version (always zero) |
| 61 uint8 version = 0; |
| 62 |
| 63 PrependInteger(coefficient_, &content); |
| 64 PrependInteger(exponent2_, &content); |
| 65 PrependInteger(exponent1_, &content); |
| 66 PrependInteger(prime2_, &content); |
| 67 PrependInteger(prime1_, &content); |
| 68 PrependInteger(private_exponent_, &content); |
| 69 PrependInteger(public_exponent_, &content); |
| 70 PrependInteger(modulus_, &content); |
| 71 PrependInteger(&version, 1, &content); |
| 72 PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content); |
| 73 PrependTypeHeaderAndLength(kOctetStringTag, content.size(), &content); |
| 74 |
| 75 // RSA algorithm OID |
| 76 for (size_t i = sizeof(kRsaAlgorithmIdentifier); i > 0; --i) |
| 77 content.push_front(kRsaAlgorithmIdentifier[i - 1]); |
| 78 |
| 79 PrependInteger(&version, 1, &content); |
| 80 PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content); |
| 81 |
| 82 // Copy everying into the output. |
| 83 output->reserve(content.size()); |
| 84 output->assign(content.begin(), content.end()); |
| 85 |
| 86 return true; |
| 87 } |
| 88 |
| 89 bool PrivateKeyInfoCodec::ExportPublicKeyInfo(std::vector<uint8>* output) { |
| 90 // Create a sequence with the modulus (n) and public exponent (e). |
| 91 std::vector<uint8> bit_string; |
| 92 if (!ExportPublicKey(&bit_string)) |
| 93 return false; |
| 94 |
| 95 // Add the sequence as the contents of a bit string. |
| 96 std::list<uint8> content; |
| 97 PrependBitString(&bit_string[0], static_cast<int>(bit_string.size()), |
| 98 &content); |
| 99 |
| 100 // Add the RSA algorithm OID. |
| 101 for (size_t i = sizeof(kRsaAlgorithmIdentifier); i > 0; --i) |
| 102 content.push_front(kRsaAlgorithmIdentifier[i - 1]); |
| 103 |
| 104 // Finally, wrap everything in a sequence. |
| 105 PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content); |
| 106 |
| 107 // Copy everything into the output. |
| 108 output->reserve(content.size()); |
| 109 output->assign(content.begin(), content.end()); |
| 110 |
| 111 return true; |
| 112 } |
| 113 |
| 114 bool PrivateKeyInfoCodec::ExportPublicKey(std::vector<uint8>* output) { |
| 115 // Create a sequence with the modulus (n) and public exponent (e). |
| 116 std::list<uint8> content; |
| 117 PrependInteger(&public_exponent_[0], |
| 118 static_cast<int>(public_exponent_.size()), |
| 119 &content); |
| 120 PrependInteger(&modulus_[0], static_cast<int>(modulus_.size()), &content); |
| 121 PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content); |
| 122 |
| 123 // Copy everything into the output. |
| 124 output->reserve(content.size()); |
| 125 output->assign(content.begin(), content.end()); |
| 126 |
| 127 return true; |
| 128 } |
| 129 |
| 130 bool PrivateKeyInfoCodec::Import(const std::vector<uint8>& input) { |
| 131 if (input.empty()) { |
| 132 return false; |
| 133 } |
| 134 |
| 135 // Parse the private key info up to the public key values, ignoring |
| 136 // the subsequent private key values. |
| 137 uint8* src = const_cast<uint8*>(&input.front()); |
| 138 uint8* end = src + input.size(); |
| 139 if (!ReadSequence(&src, end) || |
| 140 !ReadVersion(&src, end) || |
| 141 !ReadAlgorithmIdentifier(&src, end) || |
| 142 !ReadTypeHeaderAndLength(&src, end, kOctetStringTag, NULL) || |
| 143 !ReadSequence(&src, end) || |
| 144 !ReadVersion(&src, end) || |
| 145 !ReadInteger(&src, end, &modulus_)) |
| 146 return false; |
| 147 |
| 148 int mod_size = modulus_.size(); |
| 149 READ_ASSERT(mod_size % 2 == 0); |
| 150 int primes_size = mod_size / 2; |
| 151 |
| 152 if (!ReadIntegerWithExpectedSize(&src, end, 4, &public_exponent_) || |
| 153 !ReadIntegerWithExpectedSize(&src, end, mod_size, &private_exponent_) || |
| 154 !ReadIntegerWithExpectedSize(&src, end, primes_size, &prime1_) || |
| 155 !ReadIntegerWithExpectedSize(&src, end, primes_size, &prime2_) || |
| 156 !ReadIntegerWithExpectedSize(&src, end, primes_size, &exponent1_) || |
| 157 !ReadIntegerWithExpectedSize(&src, end, primes_size, &exponent2_) || |
| 158 !ReadIntegerWithExpectedSize(&src, end, primes_size, &coefficient_)) |
| 159 return false; |
| 160 |
| 161 READ_ASSERT(src == end); |
| 162 |
| 163 |
| 164 return true; |
| 165 } |
| 166 |
| 167 void PrivateKeyInfoCodec::PrependInteger(const std::vector<uint8>& in, |
| 168 std::list<uint8>* out) { |
| 169 uint8* ptr = const_cast<uint8*>(&in.front()); |
| 170 PrependIntegerImpl(ptr, in.size(), out, big_endian_); |
| 171 } |
| 172 |
| 173 // Helper to prepend an ASN.1 integer. |
| 174 void PrivateKeyInfoCodec::PrependInteger(uint8* val, |
| 175 int num_bytes, |
| 176 std::list<uint8>* data) { |
| 177 PrependIntegerImpl(val, num_bytes, data, big_endian_); |
| 178 } |
| 179 |
| 180 void PrivateKeyInfoCodec::PrependIntegerImpl(uint8* val, |
| 181 int num_bytes, |
| 182 std::list<uint8>* data, |
| 183 bool big_endian) { |
| 184 // Reverse input if little-endian. |
| 185 std::vector<uint8> tmp; |
| 186 if (!big_endian) { |
| 187 tmp.assign(val, val + num_bytes); |
| 188 std::reverse(tmp.begin(), tmp.end()); |
| 189 val = &tmp.front(); |
| 190 } |
| 191 |
| 192 // ASN.1 integers are unpadded byte arrays, so skip any null padding bytes |
| 193 // from the most-significant end of the integer. |
| 194 int start = 0; |
| 195 while (start < (num_bytes - 1) && val[start] == 0x00) { |
| 196 start++; |
| 197 num_bytes--; |
| 198 } |
| 199 PrependBytes(val, start, num_bytes, data); |
| 200 |
| 201 // ASN.1 integers are signed. To encode a positive integer whose sign bit |
| 202 // (the most significant bit) would otherwise be set and make the number |
| 203 // negative, ASN.1 requires a leading null byte to force the integer to be |
| 204 // positive. |
| 205 uint8 front = data->front(); |
| 206 if ((front & 0x80) != 0) { |
| 207 data->push_front(0x00); |
| 208 num_bytes++; |
| 209 } |
| 210 |
| 211 PrependTypeHeaderAndLength(kIntegerTag, num_bytes, data); |
| 212 } |
| 213 |
| 214 bool PrivateKeyInfoCodec::ReadInteger(uint8** pos, |
| 215 uint8* end, |
| 216 std::vector<uint8>* out) { |
| 217 return ReadIntegerImpl(pos, end, out, big_endian_); |
| 218 } |
| 219 |
| 220 bool PrivateKeyInfoCodec::ReadIntegerWithExpectedSize(uint8** pos, |
| 221 uint8* end, |
| 222 size_t expected_size, |
| 223 std::vector<uint8>* out) { |
| 224 std::vector<uint8> temp; |
| 225 if (!ReadIntegerImpl(pos, end, &temp, true)) // Big-Endian |
| 226 return false; |
| 227 |
| 228 int pad = expected_size - temp.size(); |
| 229 int index = 0; |
| 230 if (out->size() == expected_size + 1) { |
| 231 READ_ASSERT(out->front() == 0x00); |
| 232 pad++; |
| 233 index++; |
| 234 } else { |
| 235 READ_ASSERT(out->size() <= expected_size); |
| 236 } |
| 237 |
| 238 out->insert(out->end(), pad, 0x00); |
| 239 out->insert(out->end(), temp.begin(), temp.end()); |
| 240 |
| 241 // Reverse output if little-endian. |
| 242 if (!big_endian_) |
| 243 std::reverse(out->begin(), out->end()); |
| 244 return true; |
| 245 } |
| 246 |
| 247 bool PrivateKeyInfoCodec::ReadIntegerImpl(uint8** pos, |
| 248 uint8* end, |
| 249 std::vector<uint8>* out, |
| 250 bool big_endian) { |
| 251 uint32 length = 0; |
| 252 if (!ReadTypeHeaderAndLength(pos, end, kIntegerTag, &length) || !length) |
| 253 return false; |
| 254 |
| 255 // The first byte can be zero to force positiveness. We can ignore this. |
| 256 if (**pos == 0x00) { |
| 257 ++(*pos); |
| 258 --length; |
| 259 } |
| 260 |
| 261 if (length) |
| 262 out->insert(out->end(), *pos, (*pos) + length); |
| 263 |
| 264 (*pos) += length; |
| 265 |
| 266 // Reverse output if little-endian. |
| 267 if (!big_endian) |
| 268 std::reverse(out->begin(), out->end()); |
| 269 return true; |
| 270 } |
| 271 |
| 272 void PrivateKeyInfoCodec::PrependBytes(uint8* val, |
| 273 int start, |
| 274 int num_bytes, |
| 275 std::list<uint8>* data) { |
| 276 while (num_bytes > 0) { |
| 277 --num_bytes; |
| 278 data->push_front(val[start + num_bytes]); |
| 279 } |
| 280 } |
| 281 |
| 282 void PrivateKeyInfoCodec::PrependLength(size_t size, std::list<uint8>* data) { |
| 283 // The high bit is used to indicate whether additional octets are needed to |
| 284 // represent the length. |
| 285 if (size < 0x80) { |
| 286 data->push_front(static_cast<uint8>(size)); |
| 287 } else { |
| 288 uint8 num_bytes = 0; |
| 289 while (size > 0) { |
| 290 data->push_front(static_cast<uint8>(size & 0xFF)); |
| 291 size >>= 8; |
| 292 num_bytes++; |
| 293 } |
| 294 CHECK_LE(num_bytes, 4); |
| 295 data->push_front(0x80 | num_bytes); |
| 296 } |
| 297 } |
| 298 |
| 299 void PrivateKeyInfoCodec::PrependTypeHeaderAndLength(uint8 type, |
| 300 uint32 length, |
| 301 std::list<uint8>* output) { |
| 302 PrependLength(length, output); |
| 303 output->push_front(type); |
| 304 } |
| 305 |
| 306 void PrivateKeyInfoCodec::PrependBitString(uint8* val, |
| 307 int num_bytes, |
| 308 std::list<uint8>* output) { |
| 309 // Start with the data. |
| 310 PrependBytes(val, 0, num_bytes, output); |
| 311 // Zero unused bits. |
| 312 output->push_front(0); |
| 313 // Add the length. |
| 314 PrependLength(num_bytes + 1, output); |
| 315 // Finally, add the bit string tag. |
| 316 output->push_front((uint8) kBitStringTag); |
| 317 } |
| 318 |
| 319 bool PrivateKeyInfoCodec::ReadLength(uint8** pos, uint8* end, uint32* result) { |
| 320 READ_ASSERT(*pos < end); |
| 321 int length = 0; |
| 322 |
| 323 // If the MSB is not set, the length is just the byte itself. |
| 324 if (!(**pos & 0x80)) { |
| 325 length = **pos; |
| 326 (*pos)++; |
| 327 } else { |
| 328 // Otherwise, the lower 7 indicate the length of the length. |
| 329 int length_of_length = **pos & 0x7F; |
| 330 READ_ASSERT(length_of_length <= 4); |
| 331 (*pos)++; |
| 332 READ_ASSERT(*pos + length_of_length < end); |
| 333 |
| 334 length = 0; |
| 335 for (int i = 0; i < length_of_length; ++i) { |
| 336 length <<= 8; |
| 337 length |= **pos; |
| 338 (*pos)++; |
| 339 } |
| 340 } |
| 341 |
| 342 READ_ASSERT(*pos + length <= end); |
| 343 if (result) *result = length; |
| 344 return true; |
| 345 } |
| 346 |
| 347 bool PrivateKeyInfoCodec::ReadTypeHeaderAndLength(uint8** pos, |
| 348 uint8* end, |
| 349 uint8 expected_tag, |
| 350 uint32* length) { |
| 351 READ_ASSERT(*pos < end); |
| 352 READ_ASSERT(**pos == expected_tag); |
| 353 (*pos)++; |
| 354 |
| 355 return ReadLength(pos, end, length); |
| 356 } |
| 357 |
| 358 bool PrivateKeyInfoCodec::ReadSequence(uint8** pos, uint8* end) { |
| 359 return ReadTypeHeaderAndLength(pos, end, kSequenceTag, NULL); |
| 360 } |
| 361 |
| 362 bool PrivateKeyInfoCodec::ReadAlgorithmIdentifier(uint8** pos, uint8* end) { |
| 363 READ_ASSERT(*pos + sizeof(kRsaAlgorithmIdentifier) < end); |
| 364 READ_ASSERT(memcmp(*pos, kRsaAlgorithmIdentifier, |
| 365 sizeof(kRsaAlgorithmIdentifier)) == 0); |
| 366 (*pos) += sizeof(kRsaAlgorithmIdentifier); |
| 367 return true; |
| 368 } |
| 369 |
| 370 bool PrivateKeyInfoCodec::ReadVersion(uint8** pos, uint8* end) { |
| 371 uint32 length = 0; |
| 372 if (!ReadTypeHeaderAndLength(pos, end, kIntegerTag, &length)) |
| 373 return false; |
| 374 |
| 375 // The version should be zero. |
| 376 for (uint32 i = 0; i < length; ++i) { |
| 377 READ_ASSERT(**pos == 0x00); |
| 378 (*pos)++; |
| 379 } |
| 380 |
| 381 return true; |
| 382 } |
| 383 |
| 384 } // namespace crypto |
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