Torne (Richard Coles) | 5821806 | 2012-11-14 11:43:16 +0000 | [diff] [blame] | 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" |
Torne (Richard Coles) | 868fa2f | 2013-06-11 10:57:03 +0100 | [diff] [blame] | 12 | #include "base/strings/string_util.h" |
Torne (Richard Coles) | 5821806 | 2012-11-14 11:43:16 +0000 | [diff] [blame] | 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 |