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// Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <cstring> // memcpy
#include <base/stl_util.h>
#include <base/strings/string_number_conversions.h>
#include "brillo/secure_blob.h"
namespace brillo {
namespace {
bool ConvertHexToBytes(char c, uint8_t* v) {
if (c >= '0' && c <='9')
*v = c - '0';
else if (c >= 'a' && c <= 'f')
*v = c - 'a' + 10;
else if (c >= 'A' && c <= 'F')
*v = c - 'A' + 10;
else
return false;
return true;
}
} // namespace
std::string BlobToString(const Blob& blob) {
return std::string(blob.begin(), blob.end());
}
Blob BlobFromString(const std::string& bytes) {
return Blob(bytes.begin(), bytes.end());
}
Blob CombineBlobs(const std::initializer_list<Blob>& blobs) {
size_t total_size = 0;
for (const auto& blob : blobs)
total_size += blob.size();
Blob concatenation;
concatenation.reserve(total_size);
for (const auto& blob : blobs)
concatenation.insert(concatenation.end(), blob.begin(), blob.end());
return concatenation;
}
SecureBlob::SecureBlob(const Blob& blob)
: SecureBlob(blob.begin(), blob.end()) {}
SecureBlob::SecureBlob(const std::string& data)
: SecureBlob(data.begin(), data.end()) {}
SecureBlob::~SecureBlob() {
clear();
}
void SecureBlob::resize(size_type count) {
if (count < size()) {
SecureMemset(data() + count, 0, capacity() - count);
}
Blob::resize(count);
}
void SecureBlob::resize(size_type count, const value_type& value) {
if (count < size()) {
SecureMemset(data() + count, 0, capacity() - count);
}
Blob::resize(count, value);
}
void SecureBlob::clear() {
SecureMemset(data(), 0, capacity());
Blob::clear();
}
std::string SecureBlob::to_string() const {
return std::string(data(), data() + size());
}
SecureBlob SecureBlob::Combine(const SecureBlob& blob1,
const SecureBlob& blob2) {
SecureBlob result;
result.reserve(blob1.size() + blob2.size());
result.insert(result.end(), blob1.begin(), blob1.end());
result.insert(result.end(), blob2.begin(), blob2.end());
return result;
}
bool SecureBlob::HexStringToSecureBlob(const std::string& input,
SecureBlob* output) {
// TODO(jorgelo,crbug.com/728047): Consider not using an intermediate
// std::vector here at all.
std::vector<uint8_t> temp;
if (!base::HexStringToBytes(input, &temp)) {
output->clear();
return false;
}
output->assign(temp.begin(), temp.end());
SecureMemset(temp.data(), 0, temp.capacity());
return true;
}
BRILLO_DISABLE_ASAN void* SecureMemset(void* v, int c, size_t n) {
volatile uint8_t* p = reinterpret_cast<volatile uint8_t*>(v);
while (n--)
*p++ = c;
return v;
}
int SecureMemcmp(const void* s1, const void* s2, size_t n) {
const uint8_t* us1 = reinterpret_cast<const uint8_t*>(s1);
const uint8_t* us2 = reinterpret_cast<const uint8_t*>(s2);
int result = 0;
if (0 == n)
return 1;
/* Code snippet without data-dependent branch due to
* Nate Lawson (nate@root.org) of Root Labs. */
while (n--)
result |= *us1++ ^ *us2++;
return result != 0;
}
// base::HexEncode and base::HexStringToBytes use strings, which may leak
// contents. These functions are alternatives that keep all contents
// within secured memory.
SecureBlob SecureBlobToSecureHex(const SecureBlob& blob) {
std::string kHexChars("0123456789ABCDEF");
SecureBlob hex(blob.size() * 2, 0);
const char* blob_char_data = blob.char_data();
// Each input byte creates two output hex characters.
for (size_t i = 0; i < blob.size(); ++i) {
hex[(i * 2)] = kHexChars[(blob_char_data[i] >> 4) & 0xf];
hex[(i * 2) + 1] = kHexChars[blob_char_data[i] & 0xf];
}
return hex;
}
SecureBlob SecureHexToSecureBlob(const SecureBlob& hex) {
SecureBlob blob(hex.size()/2, 0);
if (hex.size() == 0 || hex.size() % 2)
return SecureBlob();
for (size_t i = 0; i < hex.size(); i++) {
uint8_t v;
// Check for invalid characters.
if (!ConvertHexToBytes(hex[i], &v))
return SecureBlob();
blob[i/2] = (blob[i/2] << 4) | (v & 0xf);
}
return blob;
}
} // namespace brillo
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