389 lines
12 KiB
C++
389 lines
12 KiB
C++
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "crypto/rsa_private_key.h"
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#include <stddef.h>
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#include <stdint.h>
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#include <algorithm>
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#include "base/logging.h"
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#include "base/memory/scoped_ptr.h"
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#include "base/strings/string_util.h"
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// This file manually encodes and decodes RSA private keys using PrivateKeyInfo
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// from PKCS #8 and RSAPrivateKey from PKCS #1. These structures are:
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//
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// PrivateKeyInfo ::= SEQUENCE {
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// version Version,
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// privateKeyAlgorithm PrivateKeyAlgorithmIdentifier,
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// privateKey PrivateKey,
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// attributes [0] IMPLICIT Attributes OPTIONAL
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// }
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//
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// RSAPrivateKey ::= SEQUENCE {
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// version Version,
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// modulus INTEGER,
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// publicExponent INTEGER,
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// privateExponent INTEGER,
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// prime1 INTEGER,
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// prime2 INTEGER,
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// exponent1 INTEGER,
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// exponent2 INTEGER,
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// coefficient INTEGER
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// }
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namespace {
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// Helper for error handling during key import.
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#define READ_ASSERT(truth) \
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if (!(truth)) { \
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NOTREACHED(); \
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return false; \
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}
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} // namespace
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namespace crypto {
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const uint8_t PrivateKeyInfoCodec::kRsaAlgorithmIdentifier[] = {
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0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86,
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0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00};
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PrivateKeyInfoCodec::PrivateKeyInfoCodec(bool big_endian)
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: big_endian_(big_endian) {}
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PrivateKeyInfoCodec::~PrivateKeyInfoCodec() {}
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bool PrivateKeyInfoCodec::Export(std::vector<uint8_t>* output) {
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std::list<uint8_t> content;
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// Version (always zero)
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uint8_t version = 0;
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PrependInteger(coefficient_, &content);
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PrependInteger(exponent2_, &content);
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PrependInteger(exponent1_, &content);
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PrependInteger(prime2_, &content);
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PrependInteger(prime1_, &content);
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PrependInteger(private_exponent_, &content);
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PrependInteger(public_exponent_, &content);
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PrependInteger(modulus_, &content);
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PrependInteger(&version, 1, &content);
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PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content);
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PrependTypeHeaderAndLength(kOctetStringTag, content.size(), &content);
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// RSA algorithm OID
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for (size_t i = sizeof(kRsaAlgorithmIdentifier); i > 0; --i)
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content.push_front(kRsaAlgorithmIdentifier[i - 1]);
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PrependInteger(&version, 1, &content);
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PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content);
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// Copy everying into the output.
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output->reserve(content.size());
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output->assign(content.begin(), content.end());
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return true;
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}
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bool PrivateKeyInfoCodec::ExportPublicKeyInfo(std::vector<uint8_t>* output) {
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// Create a sequence with the modulus (n) and public exponent (e).
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std::vector<uint8_t> bit_string;
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if (!ExportPublicKey(&bit_string))
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return false;
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// Add the sequence as the contents of a bit string.
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std::list<uint8_t> content;
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PrependBitString(&bit_string[0], static_cast<int>(bit_string.size()),
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&content);
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// Add the RSA algorithm OID.
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for (size_t i = sizeof(kRsaAlgorithmIdentifier); i > 0; --i)
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content.push_front(kRsaAlgorithmIdentifier[i - 1]);
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// Finally, wrap everything in a sequence.
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PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content);
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// Copy everything into the output.
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output->reserve(content.size());
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output->assign(content.begin(), content.end());
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return true;
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}
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bool PrivateKeyInfoCodec::ExportPublicKey(std::vector<uint8_t>* output) {
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// Create a sequence with the modulus (n) and public exponent (e).
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std::list<uint8_t> content;
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PrependInteger(&public_exponent_[0],
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static_cast<int>(public_exponent_.size()),
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&content);
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PrependInteger(&modulus_[0], static_cast<int>(modulus_.size()), &content);
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PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content);
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// Copy everything into the output.
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output->reserve(content.size());
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output->assign(content.begin(), content.end());
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return true;
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}
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bool PrivateKeyInfoCodec::Import(const std::vector<uint8_t>& input) {
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if (input.empty()) {
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return false;
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}
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// Parse the private key info up to the public key values, ignoring
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// the subsequent private key values.
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uint8_t* src = const_cast<uint8_t*>(&input.front());
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uint8_t* end = src + input.size();
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if (!ReadSequence(&src, end) ||
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!ReadVersion(&src, end) ||
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!ReadAlgorithmIdentifier(&src, end) ||
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!ReadTypeHeaderAndLength(&src, end, kOctetStringTag, NULL) ||
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!ReadSequence(&src, end) ||
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!ReadVersion(&src, end) ||
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!ReadInteger(&src, end, &modulus_))
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return false;
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int mod_size = modulus_.size();
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READ_ASSERT(mod_size % 2 == 0);
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int primes_size = mod_size / 2;
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if (!ReadIntegerWithExpectedSize(&src, end, 4, &public_exponent_) ||
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!ReadIntegerWithExpectedSize(&src, end, mod_size, &private_exponent_) ||
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!ReadIntegerWithExpectedSize(&src, end, primes_size, &prime1_) ||
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!ReadIntegerWithExpectedSize(&src, end, primes_size, &prime2_) ||
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!ReadIntegerWithExpectedSize(&src, end, primes_size, &exponent1_) ||
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!ReadIntegerWithExpectedSize(&src, end, primes_size, &exponent2_) ||
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!ReadIntegerWithExpectedSize(&src, end, primes_size, &coefficient_))
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return false;
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READ_ASSERT(src == end);
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return true;
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}
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void PrivateKeyInfoCodec::PrependInteger(const std::vector<uint8_t>& in,
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std::list<uint8_t>* out) {
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uint8_t* ptr = const_cast<uint8_t*>(&in.front());
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PrependIntegerImpl(ptr, in.size(), out, big_endian_);
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}
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// Helper to prepend an ASN.1 integer.
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void PrivateKeyInfoCodec::PrependInteger(uint8_t* val,
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int num_bytes,
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std::list<uint8_t>* data) {
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PrependIntegerImpl(val, num_bytes, data, big_endian_);
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}
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void PrivateKeyInfoCodec::PrependIntegerImpl(uint8_t* val,
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int num_bytes,
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std::list<uint8_t>* data,
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bool big_endian) {
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// Reverse input if little-endian.
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std::vector<uint8_t> tmp;
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if (!big_endian) {
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tmp.assign(val, val + num_bytes);
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std::reverse(tmp.begin(), tmp.end());
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val = &tmp.front();
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}
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// ASN.1 integers are unpadded byte arrays, so skip any null padding bytes
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// from the most-significant end of the integer.
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int start = 0;
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while (start < (num_bytes - 1) && val[start] == 0x00) {
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start++;
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num_bytes--;
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}
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PrependBytes(val, start, num_bytes, data);
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// ASN.1 integers are signed. To encode a positive integer whose sign bit
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// (the most significant bit) would otherwise be set and make the number
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// negative, ASN.1 requires a leading null byte to force the integer to be
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// positive.
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uint8_t front = data->front();
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if ((front & 0x80) != 0) {
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data->push_front(0x00);
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num_bytes++;
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}
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PrependTypeHeaderAndLength(kIntegerTag, num_bytes, data);
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}
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bool PrivateKeyInfoCodec::ReadInteger(uint8_t** pos,
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uint8_t* end,
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std::vector<uint8_t>* out) {
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return ReadIntegerImpl(pos, end, out, big_endian_);
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}
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bool PrivateKeyInfoCodec::ReadIntegerWithExpectedSize(
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uint8_t** pos,
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uint8_t* end,
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size_t expected_size,
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std::vector<uint8_t>* out) {
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std::vector<uint8_t> temp;
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if (!ReadIntegerImpl(pos, end, &temp, true)) // Big-Endian
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return false;
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int pad = expected_size - temp.size();
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int index = 0;
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if (out->size() == expected_size + 1) {
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READ_ASSERT(out->front() == 0x00);
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pad++;
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index++;
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} else {
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READ_ASSERT(out->size() <= expected_size);
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}
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out->insert(out->end(), pad, 0x00);
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out->insert(out->end(), temp.begin(), temp.end());
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// Reverse output if little-endian.
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if (!big_endian_)
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std::reverse(out->begin(), out->end());
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return true;
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}
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bool PrivateKeyInfoCodec::ReadIntegerImpl(uint8_t** pos,
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uint8_t* end,
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std::vector<uint8_t>* out,
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bool big_endian) {
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uint32_t length = 0;
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if (!ReadTypeHeaderAndLength(pos, end, kIntegerTag, &length) || !length)
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return false;
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// The first byte can be zero to force positiveness. We can ignore this.
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if (**pos == 0x00) {
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++(*pos);
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--length;
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}
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if (length)
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out->insert(out->end(), *pos, (*pos) + length);
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(*pos) += length;
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// Reverse output if little-endian.
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if (!big_endian)
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std::reverse(out->begin(), out->end());
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return true;
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}
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void PrivateKeyInfoCodec::PrependBytes(uint8_t* val,
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int start,
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int num_bytes,
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std::list<uint8_t>* data) {
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while (num_bytes > 0) {
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--num_bytes;
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data->push_front(val[start + num_bytes]);
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}
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}
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void PrivateKeyInfoCodec::PrependLength(size_t size, std::list<uint8_t>* data) {
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// The high bit is used to indicate whether additional octets are needed to
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// represent the length.
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if (size < 0x80) {
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data->push_front(static_cast<uint8_t>(size));
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} else {
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uint8_t num_bytes = 0;
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while (size > 0) {
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data->push_front(static_cast<uint8_t>(size & 0xFF));
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size >>= 8;
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num_bytes++;
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}
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CHECK_LE(num_bytes, 4);
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data->push_front(0x80 | num_bytes);
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}
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}
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void PrivateKeyInfoCodec::PrependTypeHeaderAndLength(
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uint8_t type,
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uint32_t length,
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std::list<uint8_t>* output) {
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PrependLength(length, output);
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output->push_front(type);
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}
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void PrivateKeyInfoCodec::PrependBitString(uint8_t* val,
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int num_bytes,
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std::list<uint8_t>* output) {
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// Start with the data.
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PrependBytes(val, 0, num_bytes, output);
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// Zero unused bits.
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output->push_front(0);
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// Add the length.
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PrependLength(num_bytes + 1, output);
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// Finally, add the bit string tag.
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output->push_front((uint8_t)kBitStringTag);
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}
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bool PrivateKeyInfoCodec::ReadLength(uint8_t** pos,
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uint8_t* end,
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uint32_t* result) {
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READ_ASSERT(*pos < end);
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int length = 0;
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// If the MSB is not set, the length is just the byte itself.
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if (!(**pos & 0x80)) {
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length = **pos;
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(*pos)++;
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} else {
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// Otherwise, the lower 7 indicate the length of the length.
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int length_of_length = **pos & 0x7F;
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READ_ASSERT(length_of_length <= 4);
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(*pos)++;
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READ_ASSERT(*pos + length_of_length < end);
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length = 0;
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for (int i = 0; i < length_of_length; ++i) {
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length <<= 8;
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length |= **pos;
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(*pos)++;
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}
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}
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READ_ASSERT(*pos + length <= end);
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if (result) *result = length;
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return true;
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}
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bool PrivateKeyInfoCodec::ReadTypeHeaderAndLength(uint8_t** pos,
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uint8_t* end,
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uint8_t expected_tag,
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uint32_t* length) {
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READ_ASSERT(*pos < end);
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READ_ASSERT(**pos == expected_tag);
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(*pos)++;
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return ReadLength(pos, end, length);
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}
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bool PrivateKeyInfoCodec::ReadSequence(uint8_t** pos, uint8_t* end) {
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return ReadTypeHeaderAndLength(pos, end, kSequenceTag, NULL);
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}
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bool PrivateKeyInfoCodec::ReadAlgorithmIdentifier(uint8_t** pos, uint8_t* end) {
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READ_ASSERT(*pos + sizeof(kRsaAlgorithmIdentifier) < end);
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READ_ASSERT(memcmp(*pos, kRsaAlgorithmIdentifier,
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sizeof(kRsaAlgorithmIdentifier)) == 0);
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(*pos) += sizeof(kRsaAlgorithmIdentifier);
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return true;
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}
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bool PrivateKeyInfoCodec::ReadVersion(uint8_t** pos, uint8_t* end) {
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uint32_t length = 0;
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if (!ReadTypeHeaderAndLength(pos, end, kIntegerTag, &length))
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return false;
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// The version should be zero.
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for (uint32_t i = 0; i < length; ++i) {
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READ_ASSERT(**pos == 0x00);
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(*pos)++;
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}
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return true;
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}
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} // namespace crypto
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