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fix two crypto related todos

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This commit is contained in:
Thomas Fussell 2017-04-19 16:00:33 -04:00
parent ff56701774
commit 607e069b33
3 changed files with 48 additions and 43 deletions
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46
source/detail/crypto/aes.cpp
View File

@ -1334,19 +1334,21 @@ namespace detail {
std::vector<std::uint8_t> aes_ecb_encrypt( std::vector<std::uint8_t> aes_ecb_encrypt(
const std::vector<std::uint8_t> &plaintext, const std::vector<std::uint8_t> &plaintext,
const std::vector<std::uint8_t> &key) const std::vector<std::uint8_t> &key,
const std::size_t offset)
{ {
if (plaintext.empty()) return {}; if (plaintext.empty()) return {};
if (plaintext.size() % 16 != 0) auto len = plaintext.size() - offset;
if (len % 16 != 0)
{ {
throw std::runtime_error(""); throw std::runtime_error("");
} }
auto ciphertext = std::vector<std::uint8_t>(plaintext.size()); auto ciphertext = std::vector<std::uint8_t>(len);
auto expanded_key = rijndael_setup(key); auto expanded_key = rijndael_setup(key);
auto len = plaintext.size(); auto pt = plaintext.data() + offset;
auto pt = plaintext.data();
auto ct = ciphertext.data(); auto ct = ciphertext.data();
while (len) while (len)
@ -1363,19 +1365,21 @@ std::vector<std::uint8_t> aes_ecb_encrypt(
std::vector<std::uint8_t> aes_ecb_decrypt( std::vector<std::uint8_t> aes_ecb_decrypt(
const std::vector<std::uint8_t> &ciphertext, const std::vector<std::uint8_t> &ciphertext,
const std::vector<std::uint8_t> &key) const std::vector<std::uint8_t> &key,
const std::size_t offset)
{ {
if (ciphertext.empty()) return {}; if (ciphertext.empty()) return {};
if (ciphertext.size() % 16 != 0) auto len = ciphertext.size() - offset;
if (len % 16 != 0)
{ {
throw std::runtime_error(""); throw std::runtime_error("");
} }
auto plaintext = std::vector<std::uint8_t>(ciphertext.size()); auto plaintext = std::vector<std::uint8_t>(len);
auto expanded_key = rijndael_setup(key); auto expanded_key = rijndael_setup(key);
auto len = ciphertext.size(); auto ct = ciphertext.data() + offset;
auto ct = ciphertext.data();
auto pt = plaintext.data(); auto pt = plaintext.data();
while (len) while (len)
@ -1393,20 +1397,22 @@ std::vector<std::uint8_t> aes_ecb_decrypt(
std::vector<std::uint8_t> aes_cbc_encrypt( std::vector<std::uint8_t> aes_cbc_encrypt(
const std::vector<std::uint8_t> &plaintext, const std::vector<std::uint8_t> &plaintext,
const std::vector<std::uint8_t> &key, const std::vector<std::uint8_t> &key,
const std::vector<std::uint8_t> &original_iv) const std::vector<std::uint8_t> &original_iv,
const std::size_t offset)
{ {
if (plaintext.empty()) return {}; if (plaintext.empty()) return {};
if (plaintext.size() % 16 != 0) auto len = plaintext.size() - offset;
if (len % 16 != 0)
{ {
throw std::runtime_error(""); throw std::runtime_error("");
} }
auto ciphertext = std::vector<std::uint8_t>(plaintext.size()); auto ciphertext = std::vector<std::uint8_t>(len);
auto expanded_key = rijndael_setup(key); auto expanded_key = rijndael_setup(key);
auto len = plaintext.size();
auto ct = ciphertext.data(); auto ct = ciphertext.data();
auto pt = plaintext.data(); auto pt = plaintext.data() + offset;
auto iv_vec = original_iv; auto iv_vec = original_iv;
auto iv = iv_vec.data(); auto iv = iv_vec.data();
@ -1435,10 +1441,13 @@ std::vector<std::uint8_t> aes_cbc_encrypt(
std::vector<std::uint8_t> aes_cbc_decrypt( std::vector<std::uint8_t> aes_cbc_decrypt(
const std::vector<std::uint8_t> &ciphertext, const std::vector<std::uint8_t> &ciphertext,
const std::vector<std::uint8_t> &key, const std::vector<std::uint8_t> &key,
const std::vector<std::uint8_t> &original_iv) const std::vector<std::uint8_t> &original_iv,
const std::size_t offset)
{ {
if (ciphertext.empty()) return {}; if (ciphertext.empty()) return {};
auto len = ciphertext.size() - offset;
if (ciphertext.size() % 16 != 0) if (ciphertext.size() % 16 != 0)
{ {
throw std::runtime_error(""); throw std::runtime_error("");
@ -1446,10 +1455,9 @@ std::vector<std::uint8_t> aes_cbc_decrypt(
std::array<std::uint8_t, 16> temporary{{0}}; std::array<std::uint8_t, 16> temporary{{0}};
auto plaintext = std::vector<std::uint8_t>(ciphertext.size()); auto plaintext = std::vector<std::uint8_t>(len);
auto expanded_key = rijndael_setup(key); auto expanded_key = rijndael_setup(key);
auto len = ciphertext.size(); auto ct = ciphertext.data() + offset;
auto ct = ciphertext.data();
auto pt = plaintext.data(); auto pt = plaintext.data();
auto iv_vec = original_iv; auto iv_vec = original_iv;
auto iv = iv_vec.data(); auto iv = iv_vec.data();

12
source/detail/crypto/aes.hpp
View File

@ -31,21 +31,25 @@ namespace detail {
std::vector<std::uint8_t> aes_ecb_encrypt( std::vector<std::uint8_t> aes_ecb_encrypt(
const std::vector<std::uint8_t> &input, const std::vector<std::uint8_t> &input,
const std::vector<std::uint8_t> &key); const std::vector<std::uint8_t> &key,
const std::size_t offset = 0);
std::vector<std::uint8_t> aes_ecb_decrypt( std::vector<std::uint8_t> aes_ecb_decrypt(
const std::vector<std::uint8_t> &input, const std::vector<std::uint8_t> &input,
const std::vector<std::uint8_t> &key); const std::vector<std::uint8_t> &key,
const std::size_t offset = 0);
std::vector<std::uint8_t> aes_cbc_encrypt( std::vector<std::uint8_t> aes_cbc_encrypt(
const std::vector<std::uint8_t> &input, const std::vector<std::uint8_t> &input,
const std::vector<std::uint8_t> &key, const std::vector<std::uint8_t> &key,
const std::vector<std::uint8_t> &iv); const std::vector<std::uint8_t> &iv,
const std::size_t offset = 0);
std::vector<std::uint8_t> aes_cbc_decrypt( std::vector<std::uint8_t> aes_cbc_decrypt(
const std::vector<std::uint8_t> &input, const std::vector<std::uint8_t> &input,
const std::vector<std::uint8_t> &key, const std::vector<std::uint8_t> &key,
const std::vector<std::uint8_t> &iv); const std::vector<std::uint8_t> &iv,
const std::size_t offset = 0);
} // namespace detail } // namespace detail
} // namespace xlnt } // namespace xlnt

33
source/detail/crypto/xlsx_crypto.cpp
View File

@ -240,9 +240,15 @@ std::vector<std::uint8_t> decrypt_xlsx_standard(
offset += verifier_size; offset += verifier_size;
const auto verifier_hash_size = read_int<std::uint32_t>(offset, encryption_info); const auto verifier_hash_size = read_int<std::uint32_t>(offset, encryption_info);
const auto encrypted_verifier_hash_size = std::size_t(32);
std::vector<std::uint8_t> encrypted_verifier_hash(encryption_info.begin() + static_cast<std::ptrdiff_t>(offset), std::vector<std::uint8_t> encrypted_verifier_hash(encryption_info.begin() + static_cast<std::ptrdiff_t>(offset),
encryption_info.begin() + static_cast<std::ptrdiff_t>(offset + verifier_hash_size)); encryption_info.begin() + static_cast<std::ptrdiff_t>(offset + encrypted_verifier_hash_size));
offset += verifier_hash_size; offset += encrypted_verifier_hash_size;
if (offset != encryption_info.size())
{
throw xlnt::exception("extra data after encryption info");
}
// begin key generation algorithm // begin key generation algorithm
@ -301,32 +307,19 @@ std::vector<std::uint8_t> decrypt_xlsx_standard(
auto calculated_verifier_hash = hash(info.hash, auto calculated_verifier_hash = hash(info.hash,
aes_ecb_decrypt(encrypted_verifier, key)); aes_ecb_decrypt(encrypted_verifier, key));
// TODO: I can't figure out how to pad encrypted_verifier_hash to 32 bytes
// so that it matches calculated_verifier_hash after decryption so we'll just
// compare the first block (16 bytes) for now.
calculated_verifier_hash.resize(16);
encrypted_verifier_hash.resize(16);
auto decrypted_verifier_hash = aes_ecb_decrypt( auto decrypted_verifier_hash = aes_ecb_decrypt(
encrypted_verifier_hash, key); encrypted_verifier_hash, key);
decrypted_verifier_hash.resize(verifier_hash_size);
if (calculated_verifier_hash != decrypted_verifier_hash) if (calculated_verifier_hash != decrypted_verifier_hash)
{ {
throw xlnt::exception("bad password"); throw xlnt::exception("bad password");
} }
std::size_t ignore = 0; offset = 0;
auto decrypted_size = static_cast<std::size_t>( auto decrypted_size = read_int<std::uint64_t>(offset, encrypted_package);
read_int<std::uint64_t>(ignore, encrypted_package)); auto decrypted = aes_ecb_decrypt(encrypted_package, key, offset);
decrypted.resize(static_cast<std::size_t>(decrypted_size));
// TODO: don't copy encrypted package just to cut off the first 8 bytes
auto encrypted_data = std::vector<std::uint8_t>(
encrypted_package.begin() + 8,
encrypted_package.end());
auto decrypted = aes_ecb_decrypt(encrypted_data, key);
decrypted.resize(decrypted_size);
return decrypted; return decrypted;
} }