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// Copyright 2014 The Chromium 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 "components/os_crypt/ie7_password_win.h"
#include <stddef.h>
#include <stdint.h>
#include <string>
#include <vector>
#include "base/sha1.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "crypto/wincrypt_shim.h"
namespace {
// Structures that IE7/IE8 use to store a username/password.
// Some of the fields might have been incorrectly reverse engineered.
struct PreHeader {
DWORD pre_header_size; // Size of this header structure. Always 12.
DWORD header_size; // Size of the real Header: sizeof(Header) +
// item_count * sizeof(Entry);
DWORD data_size; // Size of the data referenced by the entries.
};
struct Header {
char wick[4]; // The string "WICK". I don't know what it means.
DWORD fixed_header_size; // The size of this structure without the entries:
// sizeof(Header).
DWORD item_count; // Number of entries. Should be even.
wchar_t two_letters[2]; // Two unknown bytes.
DWORD unknown[2]; // Two unknown DWORDs.
};
struct Entry {
DWORD offset; // Offset where the data referenced by this entry is
// located.
FILETIME time_stamp; // Timestamp when the password got added.
DWORD string_length; // The length of the data string.
};
// Main data structure.
struct PasswordEntry {
PreHeader pre_header; // Contains the size of the different sections.
Header header; // Contains the number of items.
Entry entry[1]; // List of entries containing a string. Even-indexed
// are usernames, odd are passwords. There may be
// several sets saved for a single url hash.
};
} // namespace
IE7PasswordInfo::IE7PasswordInfo() {
}
IE7PasswordInfo::IE7PasswordInfo(const IE7PasswordInfo& other) = default;
IE7PasswordInfo::~IE7PasswordInfo() {
}
namespace ie7_password {
bool GetUserPassFromData(const std::vector<unsigned char>& data,
std::vector<DecryptedCredentials>* credentials) {
const PasswordEntry* information =
reinterpret_cast<const PasswordEntry*>(&data.front());
// Some expected values. If it's not what we expect we don't even try to
// understand the data.
if (information->pre_header.pre_header_size != sizeof(PreHeader))
return false;
const int entry_count = information->header.item_count;
if (entry_count % 2) // Usernames and Passwords
return false;
if (information->header.fixed_header_size != sizeof(Header))
return false;
const uint8_t* offset_to_data = &data[0] +
information->pre_header.header_size +
information->pre_header.pre_header_size;
for (int i = 0; i < entry_count / 2; ++i) {
const Entry* user_entry = &information->entry[2*i];
const Entry* pass_entry = user_entry+1;
DecryptedCredentials c;
c.username = reinterpret_cast<const wchar_t*>(offset_to_data +
user_entry->offset);
c.password = reinterpret_cast<const wchar_t*>(offset_to_data +
pass_entry->offset);
credentials->push_back(c);
}
return true;
}
std::wstring GetUrlHash(const std::wstring& url) {
std::wstring lower_case_url = base::ToLowerASCII(url);
// Get a data buffer out of our std::wstring to pass to SHA1HashString.
std::string url_buffer(
reinterpret_cast<const char*>(lower_case_url.c_str()),
(lower_case_url.size() + 1) * sizeof(wchar_t));
std::string hash_bin = base::SHA1HashString(url_buffer);
std::wstring url_hash;
// Transform the buffer to an hexadecimal string.
unsigned char checksum = 0;
for (size_t i = 0; i < hash_bin.size(); ++i) {
// std::string gives signed chars, which mess with StringPrintf and
// check_sum.
unsigned char hash_byte = static_cast<unsigned char>(hash_bin[i]);
checksum += hash_byte;
url_hash += base::StringPrintf(L"%2.2X", static_cast<unsigned>(hash_byte));
}
url_hash += base::StringPrintf(L"%2.2X", checksum);
return url_hash;
}
bool DecryptPasswords(const std::wstring& url,
const std::vector<unsigned char>& data,
std::vector<DecryptedCredentials>* credentials) {
std::wstring lower_case_url = base::ToLowerASCII(url);
DATA_BLOB input = {0};
DATA_BLOB output = {0};
DATA_BLOB url_key = {0};
input.pbData = const_cast<unsigned char*>(&data.front());
input.cbData = static_cast<DWORD>((data.size()) *
sizeof(std::string::value_type));
url_key.pbData = reinterpret_cast<unsigned char*>(
const_cast<wchar_t*>(lower_case_url.data()));
url_key.cbData = static_cast<DWORD>((lower_case_url.size() + 1) *
sizeof(std::wstring::value_type));
if (CryptUnprotectData(&input, NULL, &url_key, NULL, NULL,
CRYPTPROTECT_UI_FORBIDDEN, &output)) {
// Now that we have the decrypted information, we need to understand it.
std::vector<unsigned char> decrypted_data;
decrypted_data.resize(output.cbData);
memcpy(&decrypted_data.front(), output.pbData, output.cbData);
GetUserPassFromData(decrypted_data, credentials);
LocalFree(output.pbData);
return true;
}
return false;
}
} // namespace ie7_password
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