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593 lines
24 KiB
C++
593 lines
24 KiB
C++
// Copyright (c) 2014-2016 Thomas Fussell
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, WRISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE
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//
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// @license: http://www.opensource.org/licenses/mit-license.php
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// @author: see AUTHORS file
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#include <array>
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#include <pole.h>
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#include <botan_all.h>
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#include <include_libstudxml.hpp>
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#include <detail/vector_streambuf.hpp>
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#include <detail/xlsx_consumer.hpp>
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#include <xlnt/utils/exceptions.hpp>
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#include <xlnt/workbook/workbook.hpp>
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namespace xlnt {
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namespace detail {
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struct crypto_helper
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{
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static const std::size_t segment_length = 4096;
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enum class cipher_algorithm
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{
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aes,
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rc2,
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rc4,
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des,
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desx,
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triple_des,
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triple_des_112
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};
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enum class cipher_chaining
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{
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ecb, // electronic code book
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cbc, // cipher block chaining
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cfb // cipher feedback chaining
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};
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enum class cipher_direction
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{
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encryption,
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decryption
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};
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enum class hash_algorithm
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{
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sha1,
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sha256,
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sha384,
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sha512,
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md5,
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md4,
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md2,
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ripemd128,
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ripemd160,
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whirlpool
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};
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static std::vector<std::uint8_t> aes(const std::vector<std::uint8_t> &key,
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const std::vector<std::uint8_t> &iv,
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const std::vector<std::uint8_t> &encrypted,
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cipher_chaining chaining, cipher_direction direction)
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{
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std::string cipher_name("AES-");
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cipher_name.append(std::to_string(key.size() * 8));
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cipher_name.append(chaining == cipher_chaining::ecb
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? "/ECB/NoPadding" : "/CBC/NoPadding");
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auto botan_direction = direction == cipher_direction::decryption
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? Botan::DECRYPTION : Botan::ENCRYPTION;
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Botan::Pipe pipe(Botan::get_cipher(cipher_name, key, iv, botan_direction));
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pipe.process_msg(encrypted);
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auto decrypted = pipe.read_all();
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return std::vector<std::uint8_t>(decrypted.begin(), decrypted.end());
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}
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static std::vector<std::uint8_t> decode_base64(const std::string &encoded)
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{
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Botan::Pipe pipe(new Botan::Base64_Decoder);
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pipe.process_msg(encoded);
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auto decoded = pipe.read_all();
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return std::vector<std::uint8_t>(decoded.begin(), decoded.end());
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};
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static std::vector<std::uint8_t> hash(hash_algorithm algorithm,
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const std::vector<std::uint8_t> &input)
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{
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Botan::Pipe pipe(new Botan::Hash_Filter(
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algorithm == hash_algorithm::sha512 ? "SHA-512" : "SHA-1"));
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pipe.process_msg(input);
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auto hash = pipe.read_all();
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return std::vector<std::uint8_t>(hash.begin(), hash.end());
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};
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static std::vector<std::uint8_t> get_file(POLE::Storage &storage, const std::string &name)
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{
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POLE::Stream stream(&storage, name.c_str());
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if (stream.fail()) return {};
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std::vector<std::uint8_t> bytes(stream.size(), 0);
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stream.read(bytes.data(), static_cast<unsigned long>(bytes.size()));
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return bytes;
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}
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template<typename T>
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static auto read_int(std::size_t &index, const std::vector<std::uint8_t> &raw_data)
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{
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auto result = *reinterpret_cast<const T *>(&raw_data[index]);
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index += sizeof(T);
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return result;
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};
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struct standard_encryption_info
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{
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const std::size_t spin_count = 50000;
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std::size_t block_size;
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std::size_t key_bits;
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std::size_t key_bytes;
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std::size_t hash_size;
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cipher_algorithm cipher;
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cipher_chaining chaining;
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const hash_algorithm hash = hash_algorithm::sha1;
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std::vector<std::uint8_t> salt_value;
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std::vector<std::uint8_t> verifier_hash_input;
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std::vector<std::uint8_t> verifier_hash_value;
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std::vector<std::uint8_t> encrypted_key_value;
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};
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static std::vector<std::uint8_t> decrypt_xlsx_standard(const std::vector<std::uint8_t> &encryption_info,
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const std::string &password, const std::vector<std::uint8_t> &encrypted_package)
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{
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std::size_t offset = 0;
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standard_encryption_info info;
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auto header_length = read_int<std::uint32_t>(offset, encryption_info);
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auto index_at_start = offset;
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/*auto skip_flags = */read_int<std::uint32_t>(offset, encryption_info);
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/*auto size_extra = */read_int<std::uint32_t>(offset, encryption_info);
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auto alg_id = read_int<std::uint32_t>(offset, encryption_info);
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if (alg_id == 0 || alg_id == 0x0000660E || alg_id == 0x0000660F || alg_id == 0x00006610)
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{
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info.cipher = cipher_algorithm::aes;
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}
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else
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{
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throw xlnt::exception("invalid cipher algorithm");
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}
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auto alg_id_hash = read_int<std::uint32_t>(offset, encryption_info);
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if (alg_id_hash != 0x00008004 && alg_id_hash == 0)
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{
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throw xlnt::exception("invalid hash algorithm");
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}
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info.key_bits = read_int<std::uint32_t>(offset, encryption_info);
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info.key_bytes = info.key_bits / 8;
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auto provider_type = read_int<std::uint32_t>(offset, encryption_info);
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if (provider_type != 0 && provider_type != 0x00000018)
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{
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throw xlnt::exception("invalid provider type");
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}
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read_int<std::uint32_t>(offset, encryption_info); // reserved 1
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if (read_int<std::uint32_t>(offset, encryption_info) != 0) // reserved 2
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{
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throw xlnt::exception("invalid header");
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}
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const auto csp_name_length = header_length - (offset - index_at_start);
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std::vector<std::uint16_t> csp_name_wide(
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reinterpret_cast<const std::uint16_t *>(&*(encryption_info.begin() + static_cast<std::ptrdiff_t>(offset))),
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reinterpret_cast<const std::uint16_t *>(&*(encryption_info.begin() + static_cast<std::ptrdiff_t>(offset + csp_name_length))));
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std::string csp_name(csp_name_wide.begin(), csp_name_wide.end() - 1); // without trailing null
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if (csp_name != "Microsoft Enhanced RSA and AES Cryptographic Provider (Prototype)"
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&& csp_name != "Microsoft Enhanced RSA and AES Cryptographic Provider")
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{
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throw xlnt::exception("invalid cryptographic provider");
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}
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offset += csp_name_length;
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const auto salt_size = read_int<std::uint32_t>(offset, encryption_info);
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std::vector<std::uint8_t> salt(encryption_info.begin() + static_cast<std::ptrdiff_t>(offset),
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encryption_info.begin() + static_cast<std::ptrdiff_t>(offset + salt_size));
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offset += salt_size;
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static const auto verifier_size = std::size_t(16);
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std::vector<std::uint8_t> verifier_hash_input(encryption_info.begin() + static_cast<std::ptrdiff_t>(offset),
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encryption_info.begin() + static_cast<std::ptrdiff_t>(offset + verifier_size));
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offset += verifier_size;
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const auto verifier_hash_size = read_int<std::uint32_t>(offset, encryption_info);
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std::vector<std::uint8_t> verifier_hash_value(encryption_info.begin() + static_cast<std::ptrdiff_t>(offset),
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encryption_info.begin() + static_cast<std::ptrdiff_t>(offset + verifier_hash_size));
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offset += verifier_hash_size;
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// begin key generation algorithm
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// H_0 = H(salt + password)
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auto salt_plus_password = salt;
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std::vector<std::uint16_t> password_wide(password.begin(), password.end());
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std::for_each(password_wide.begin(), password_wide.end(),
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[&salt_plus_password](std::uint16_t c)
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{
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salt_plus_password.insert(salt_plus_password.end(),
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reinterpret_cast<char *>(&c),
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reinterpret_cast<char *>(&c) + sizeof(std::uint16_t));
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});
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std::vector<std::uint8_t> h_0 = hash(info.hash, salt_plus_password);
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// H_n = H(iterator + H_n-1)
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std::vector<std::uint8_t> iterator_plus_h_n(4, 0);
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iterator_plus_h_n.insert(iterator_plus_h_n.end(), h_0.begin(), h_0.end());
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std::uint32_t &iterator = *reinterpret_cast<std::uint32_t *>(iterator_plus_h_n.data());
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std::vector<std::uint8_t> h_n;
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for (iterator = 0; iterator < info.spin_count; ++iterator)
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{
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h_n = hash(info.hash, iterator_plus_h_n);
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std::copy(h_n.begin(), h_n.end(), iterator_plus_h_n.begin() + 4);
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}
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// H_final = H(H_n + block)
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auto h_n_plus_block = h_n;
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const std::uint32_t block_number = 0;
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h_n_plus_block.insert(h_n_plus_block.end(),
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reinterpret_cast<const std::uint8_t *>(&block_number),
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reinterpret_cast<const std::uint8_t *>(&block_number) + sizeof(std::uint32_t));
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auto h_final = hash(info.hash, h_n_plus_block);
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// X1 = H(h_final ^ 0x36)
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std::vector<std::uint8_t> buffer(64, 0x36);
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for (std::size_t i = 0; i < h_final.size(); ++i)
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{
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buffer[i] = static_cast<std::uint8_t>(0x36 ^ h_final[i]);
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}
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auto X1 = hash(info.hash, buffer);
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// X2 = H(h_final ^ 0x5C)
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buffer.assign(64, 0x5c);
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for (std::size_t i = 0; i < h_final.size(); ++i)
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{
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buffer[i] = static_cast<std::uint8_t>(0x5c ^ h_final[i]);
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}
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auto X2 = hash(info.hash, buffer);
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auto X3 = X1;
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X3.insert(X3.end(), X2.begin(), X2.end());
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auto key_derived = std::vector<std::uint8_t>(X3.begin(), X3.begin() + static_cast<std::ptrdiff_t>(info.key_bytes));
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//todo: verify here
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std::size_t package_offset = 0;
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auto decrypted_size = read_int<std::uint64_t>(package_offset, encrypted_package);
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auto decrypted = aes(key_derived, {}, std::vector<std::uint8_t>(
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encrypted_package.begin() + 8, encrypted_package.end()),
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cipher_chaining::ecb, cipher_direction::decryption);
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decrypted.resize(decrypted_size);
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return decrypted;
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}
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struct agile_encryption_info
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{
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// key data
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struct
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{
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std::size_t salt_size;
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std::size_t block_size;
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std::size_t key_bits;
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std::size_t hash_size;
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std::string cipher_algorithm;
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std::string cipher_chaining;
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std::string hash_algorithm;
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std::vector<std::uint8_t> salt_value;
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} key_data;
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struct
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{
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std::vector<std::uint8_t> hmac_key;
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std::vector<std::uint8_t> hmac_value;
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} data_integrity;
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struct
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{
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std::size_t spin_count;
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std::size_t salt_size;
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std::size_t block_size;
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std::size_t key_bits;
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std::size_t hash_size;
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std::string cipher_algorithm;
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std::string cipher_chaining;
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hash_algorithm hash;
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std::vector<std::uint8_t> salt_value;
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std::vector<std::uint8_t> verifier_hash_input;
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std::vector<std::uint8_t> verifier_hash_value;
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std::vector<std::uint8_t> encrypted_key_value;
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} key_encryptor;
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};
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static std::vector<std::uint8_t> decrypt_xlsx_agile(const std::vector<std::uint8_t> &encryption_info,
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const std::string &password, const std::vector<std::uint8_t> &encrypted_package)
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{
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static const auto xmlns = std::string("http://schemas.microsoft.com/office/2006/encryption");
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static const auto xmlns_p = std::string("http://schemas.microsoft.com/office/2006/keyEncryptor/password");
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static const auto xmlns_c = std::string("http://schemas.microsoft.com/office/2006/keyEncryptor/certificate");
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agile_encryption_info result;
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xml::parser parser(encryption_info.data(), encryption_info.size(), "EncryptionInfo");
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parser.next_expect(xml::parser::event_type::start_element, xmlns, "encryption");
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parser.next_expect(xml::parser::event_type::start_element, xmlns, "keyData");
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result.key_data.salt_size = parser.attribute<std::size_t>("saltSize");
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result.key_data.block_size = parser.attribute<std::size_t>("blockSize");
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result.key_data.key_bits = parser.attribute<std::size_t>("keyBits");
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result.key_data.hash_size = parser.attribute<std::size_t>("hashSize");
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result.key_data.cipher_algorithm = parser.attribute("cipherAlgorithm");
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result.key_data.cipher_chaining = parser.attribute("cipherChaining");
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result.key_data.hash_algorithm = parser.attribute("hashAlgorithm");
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result.key_data.salt_value = decode_base64(parser.attribute("saltValue"));
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parser.next_expect(xml::parser::event_type::end_element, xmlns, "keyData");
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parser.next_expect(xml::parser::event_type::start_element, xmlns, "dataIntegrity");
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result.data_integrity.hmac_key = decode_base64(parser.attribute("encryptedHmacKey"));
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result.data_integrity.hmac_value = decode_base64(parser.attribute("encryptedHmacValue"));
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parser.next_expect(xml::parser::event_type::end_element, xmlns, "dataIntegrity");
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parser.next_expect(xml::parser::event_type::start_element, xmlns, "keyEncryptors");
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parser.next_expect(xml::parser::event_type::start_element, xmlns, "keyEncryptor");
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parser.attribute("uri");
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bool any_password_key = false;
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while (parser.peek() != xml::parser::event_type::end_element)
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{
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parser.next_expect(xml::parser::event_type::start_element);
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if (parser.namespace_() == xmlns_p && parser.name() == "encryptedKey")
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{
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any_password_key = true;
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result.key_encryptor.spin_count = parser.attribute<std::size_t>("spinCount");
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result.key_encryptor.salt_size = parser.attribute<std::size_t>("saltSize");
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result.key_encryptor.block_size = parser.attribute<std::size_t>("blockSize");
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result.key_encryptor.key_bits = parser.attribute<std::size_t>("keyBits");
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result.key_encryptor.hash_size = parser.attribute<std::size_t>("hashSize");
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result.key_encryptor.cipher_algorithm = parser.attribute("cipherAlgorithm");
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result.key_encryptor.cipher_chaining = parser.attribute("cipherChaining");
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auto hash_algorithm_string = parser.attribute("hashAlgorithm");
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if (hash_algorithm_string == "SHA512")
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{
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result.key_encryptor.hash = hash_algorithm::sha512;
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}
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else if (hash_algorithm_string == "SHA1")
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{
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result.key_encryptor.hash = hash_algorithm::sha1;
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}
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else if (hash_algorithm_string == "SHA256")
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{
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result.key_encryptor.hash = hash_algorithm::sha256;
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}
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else if (hash_algorithm_string == "SHA384")
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{
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result.key_encryptor.hash = hash_algorithm::sha384;
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}
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result.key_encryptor.salt_value = decode_base64(parser.attribute("saltValue"));
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result.key_encryptor.verifier_hash_input = decode_base64(parser.attribute("encryptedVerifierHashInput"));
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result.key_encryptor.verifier_hash_value = decode_base64(parser.attribute("encryptedVerifierHashValue"));
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result.key_encryptor.encrypted_key_value = decode_base64(parser.attribute("encryptedKeyValue"));
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}
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else
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{
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throw xlnt::unsupported("other encryption key types not supported");
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}
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parser.next_expect(xml::parser::event_type::end_element);
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}
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if (!any_password_key)
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{
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throw "no password key in keyEncryptors";
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}
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parser.next_expect(xml::parser::event_type::end_element, xmlns, "keyEncryptor");
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parser.next_expect(xml::parser::event_type::end_element, xmlns, "keyEncryptors");
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parser.next_expect(xml::parser::event_type::end_element, xmlns, "encryption");
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// begin key generation algorithm
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// H_0 = H(salt + password)
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auto salt_plus_password = result.key_encryptor.salt_value;
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std::vector<std::uint16_t> password_wide(password.begin(), password.end());
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std::for_each(password_wide.begin(), password_wide.end(),
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[&salt_plus_password](std::uint16_t c)
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{
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salt_plus_password.insert(salt_plus_password.end(),
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reinterpret_cast<char *>(&c),
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reinterpret_cast<char *>(&c) + sizeof(std::uint16_t));
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});
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auto h_0 = hash(result.key_encryptor.hash, salt_plus_password);
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// H_n = H(iterator + H_n-1)
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std::vector<std::uint8_t> iterator_plus_h_n(4, 0);
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iterator_plus_h_n.insert(iterator_plus_h_n.end(), h_0.begin(), h_0.end());
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std::uint32_t &iterator = *reinterpret_cast<std::uint32_t *>(iterator_plus_h_n.data());
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std::vector<std::uint8_t> h_n;
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|
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for (iterator = 0; iterator < result.key_encryptor.spin_count; ++iterator)
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|
{
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|
h_n = hash(result.key_encryptor.hash, iterator_plus_h_n);
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std::copy(h_n.begin(), h_n.end(), iterator_plus_h_n.begin() + 4);
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|
}
|
|
|
|
static const std::size_t block_size = 8;
|
|
|
|
auto calculate_block = [&result](
|
|
const std::vector<std::uint8_t> &raw_key,
|
|
const std::array<std::uint8_t, block_size> &block,
|
|
const std::vector<std::uint8_t> &encrypted)
|
|
{
|
|
auto combined = raw_key;
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|
combined.insert(combined.end(), block.begin(), block.end());
|
|
auto key = hash(result.key_encryptor.hash, combined);
|
|
key.resize(result.key_encryptor.key_bits / 8);
|
|
return aes(key, result.key_encryptor.salt_value, encrypted,
|
|
cipher_chaining::cbc, cipher_direction::decryption);
|
|
};
|
|
|
|
const std::array<std::uint8_t, block_size> input_block_key
|
|
= { {0xfe, 0xa7, 0xd2, 0x76, 0x3b, 0x4b, 0x9e, 0x79} };
|
|
auto hash_input = calculate_block(h_n, input_block_key,
|
|
result.key_encryptor.verifier_hash_input);
|
|
auto calculated_verifier = hash(result.key_encryptor.hash, hash_input);
|
|
|
|
const std::array<std::uint8_t, block_size> verifier_block_key
|
|
= { {0xd7, 0xaa, 0x0f, 0x6d, 0x30, 0x61, 0x34, 0x4e} };
|
|
auto expected_verifier = calculate_block(h_n, verifier_block_key,
|
|
result.key_encryptor.verifier_hash_value);
|
|
|
|
if (calculated_verifier.size() != expected_verifier.size()
|
|
|| std::mismatch(calculated_verifier.begin(), calculated_verifier.end(),
|
|
expected_verifier.begin(), expected_verifier.end())
|
|
!= std::make_pair(calculated_verifier.end(), expected_verifier.end()))
|
|
{
|
|
throw xlnt::exception("bad password");
|
|
}
|
|
|
|
const std::array<std::uint8_t, block_size> key_value_block_key
|
|
= { {0x14, 0x6e, 0x0b, 0xe7, 0xab, 0xac, 0xd0, 0xd6} };
|
|
auto key = calculate_block(h_n, key_value_block_key,
|
|
result.key_encryptor.encrypted_key_value);
|
|
|
|
auto salt_size = result.key_data.salt_size;
|
|
auto salt_with_block_key = result.key_data.salt_value;
|
|
salt_with_block_key.resize(salt_size + sizeof(std::uint32_t), 0);
|
|
|
|
auto &segment = *reinterpret_cast<std::uint32_t *>(salt_with_block_key.data() + salt_size);
|
|
auto total_size = static_cast<std::size_t>(*reinterpret_cast<const std::uint64_t *>(encrypted_package.data()));
|
|
|
|
std::vector<std::uint8_t> encrypted_segment(segment_length, 0);
|
|
std::vector<std::uint8_t> decrypted_package;
|
|
decrypted_package.reserve(encrypted_package.size() - 8);
|
|
|
|
for (std::size_t i = 8; i < encrypted_package.size(); i += segment_length)
|
|
{
|
|
auto iv = hash(result.key_encryptor.hash, salt_with_block_key);
|
|
iv.resize(16);
|
|
|
|
auto decrypted_segment = aes(key, iv, std::vector<std::uint8_t>(
|
|
encrypted_package.begin() + static_cast<std::ptrdiff_t>(i),
|
|
encrypted_package.begin() + static_cast<std::ptrdiff_t>(i) + segment_length),
|
|
cipher_chaining::cbc, cipher_direction::decryption);
|
|
|
|
decrypted_package.insert(decrypted_package.end(),
|
|
decrypted_segment.begin(), decrypted_segment.end());
|
|
|
|
++segment;
|
|
}
|
|
|
|
decrypted_package.resize(total_size);
|
|
|
|
return decrypted_package;
|
|
}
|
|
|
|
static std::vector<std::uint8_t> decrypt_xlsx(const std::vector<std::uint8_t> &bytes, const std::string &password)
|
|
{
|
|
if (bytes.empty())
|
|
{
|
|
throw xlnt::exception("empty file");
|
|
}
|
|
|
|
std::vector<char> as_chars(bytes.begin(), bytes.end());
|
|
POLE::Storage storage(as_chars.data(), static_cast<unsigned long>(bytes.size()));
|
|
|
|
if (!storage.open())
|
|
{
|
|
throw xlnt::exception("not an ole compound file");
|
|
}
|
|
|
|
auto encrypted_package = get_file(storage, "EncryptedPackage");
|
|
auto encryption_info = get_file(storage, "EncryptionInfo");
|
|
|
|
std::size_t index = 0;
|
|
|
|
auto version_major = read_int<std::uint16_t>(index, encryption_info);
|
|
auto version_minor = read_int<std::uint16_t>(index, encryption_info);
|
|
auto encryption_flags = read_int<std::uint32_t>(index, encryption_info);
|
|
|
|
// get rid of header
|
|
encryption_info.erase(encryption_info.begin(),
|
|
encryption_info.begin() + static_cast<std::ptrdiff_t>(index));
|
|
|
|
// version 4.4 is agile
|
|
if (version_major == 4 && version_minor == 4)
|
|
{
|
|
if (encryption_flags != 0x40)
|
|
{
|
|
throw xlnt::exception("bad header");
|
|
}
|
|
|
|
return decrypt_xlsx_agile(encryption_info, password, encrypted_package);
|
|
}
|
|
|
|
// not agile, only try to decrypt versions 3.2 and 4.2
|
|
if (version_minor != 2
|
|
|| (version_major != 2 && version_major != 3 && version_major != 4))
|
|
{
|
|
throw xlnt::exception("unsupported encryption version");
|
|
}
|
|
|
|
if ((encryption_flags & 0b00000011) != 0) // Reserved1 and Reserved2, MUST be 0
|
|
{
|
|
throw xlnt::exception("bad header");
|
|
}
|
|
|
|
if ((encryption_flags & 0b00000100) == 0 // fCryptoAPI
|
|
|| (encryption_flags & 0b00010000) != 0) // fExternal
|
|
{
|
|
throw xlnt::exception("extensible encryption is not supported");
|
|
}
|
|
|
|
if ((encryption_flags & 0b00100000) == 0) // fAES
|
|
{
|
|
throw xlnt::exception("not an OOXML document");
|
|
}
|
|
|
|
return decrypt_xlsx_standard(encryption_info, password, encrypted_package);
|
|
}
|
|
};
|
|
|
|
void xlsx_consumer::read(std::istream &source, const std::string &password)
|
|
{
|
|
std::vector<std::uint8_t> data((std::istreambuf_iterator<char>(source)),
|
|
(std::istreambuf_iterator<char>()));
|
|
const auto decrypted = crypto_helper::decrypt_xlsx(data, password);
|
|
vector_istreambuf decrypted_buffer(decrypted);
|
|
std::istream decrypted_stream(&decrypted_buffer);
|
|
read(decrypted_stream);
|
|
}
|
|
|
|
} // namespace detail
|
|
} // namespace xlnt
|