suyu/src/core/crypto/aes_util.cpp
Zach Hilman 10e5356e9a aes_util: Make XTSTranscode stricter about sizes
XTS with Nintendo Tweak will fail mysteriously if the sector size is not 0x4000. Upgrade the critical log to an assert to prevent undefined behavior.
2018-08-23 11:52:44 -04:00

112 lines
4.3 KiB
C++

// Copyright 2018 yuzu emulator team
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <mbedtls/cipher.h>
#include "common/assert.h"
#include "common/logging/log.h"
#include "core/crypto/aes_util.h"
#include "core/crypto/key_manager.h"
namespace Core::Crypto {
namespace {
std::vector<u8> CalculateNintendoTweak(size_t sector_id) {
std::vector<u8> out(0x10);
for (size_t i = 0xF; i <= 0xF; --i) {
out[i] = sector_id & 0xFF;
sector_id >>= 8;
}
return out;
}
} // Anonymous namespace
static_assert(static_cast<size_t>(Mode::CTR) == static_cast<size_t>(MBEDTLS_CIPHER_AES_128_CTR),
"CTR has incorrect value.");
static_assert(static_cast<size_t>(Mode::ECB) == static_cast<size_t>(MBEDTLS_CIPHER_AES_128_ECB),
"ECB has incorrect value.");
static_assert(static_cast<size_t>(Mode::XTS) == static_cast<size_t>(MBEDTLS_CIPHER_AES_128_XTS),
"XTS has incorrect value.");
// Structure to hide mbedtls types from header file
struct CipherContext {
mbedtls_cipher_context_t encryption_context;
mbedtls_cipher_context_t decryption_context;
};
template <typename Key, size_t KeySize>
Crypto::AESCipher<Key, KeySize>::AESCipher(Key key, Mode mode)
: ctx(std::make_unique<CipherContext>()) {
mbedtls_cipher_init(&ctx->encryption_context);
mbedtls_cipher_init(&ctx->decryption_context);
ASSERT_MSG((mbedtls_cipher_setup(
&ctx->encryption_context,
mbedtls_cipher_info_from_type(static_cast<mbedtls_cipher_type_t>(mode))) ||
mbedtls_cipher_setup(
&ctx->decryption_context,
mbedtls_cipher_info_from_type(static_cast<mbedtls_cipher_type_t>(mode)))) == 0,
"Failed to initialize mbedtls ciphers.");
ASSERT(
!mbedtls_cipher_setkey(&ctx->encryption_context, key.data(), KeySize * 8, MBEDTLS_ENCRYPT));
ASSERT(
!mbedtls_cipher_setkey(&ctx->decryption_context, key.data(), KeySize * 8, MBEDTLS_DECRYPT));
//"Failed to set key on mbedtls ciphers.");
}
template <typename Key, size_t KeySize>
AESCipher<Key, KeySize>::~AESCipher() {
mbedtls_cipher_free(&ctx->encryption_context);
mbedtls_cipher_free(&ctx->decryption_context);
}
template <typename Key, size_t KeySize>
void AESCipher<Key, KeySize>::SetIV(std::vector<u8> iv) {
ASSERT_MSG((mbedtls_cipher_set_iv(&ctx->encryption_context, iv.data(), iv.size()) ||
mbedtls_cipher_set_iv(&ctx->decryption_context, iv.data(), iv.size())) == 0,
"Failed to set IV on mbedtls ciphers.");
}
template <typename Key, size_t KeySize>
void AESCipher<Key, KeySize>::Transcode(const u8* src, size_t size, u8* dest, Op op) const {
auto* const context = op == Op::Encrypt ? &ctx->encryption_context : &ctx->decryption_context;
mbedtls_cipher_reset(context);
size_t written = 0;
if (mbedtls_cipher_get_cipher_mode(context) == MBEDTLS_MODE_XTS) {
mbedtls_cipher_update(context, src, size, dest, &written);
if (written != size) {
LOG_WARNING(Crypto, "Not all data was decrypted requested={:016X}, actual={:016X}.",
size, written);
}
} else {
const auto block_size = mbedtls_cipher_get_block_size(context);
for (size_t offset = 0; offset < size; offset += block_size) {
auto length = std::min<size_t>(block_size, size - offset);
mbedtls_cipher_update(context, src + offset, length, dest + offset, &written);
if (written != length) {
LOG_WARNING(Crypto, "Not all data was decrypted requested={:016X}, actual={:016X}.",
length, written);
}
}
}
mbedtls_cipher_finish(context, nullptr, nullptr);
}
template <typename Key, size_t KeySize>
void AESCipher<Key, KeySize>::XTSTranscode(const u8* src, size_t size, u8* dest, size_t sector_id,
size_t sector_size, Op op) {
ASSERT_MSG(size % sector_size == 0, "XTS decryption size must be a multiple of sector size.");
for (size_t i = 0; i < size; i += sector_size) {
SetIV(CalculateNintendoTweak(sector_id++));
Transcode<u8, u8>(src + i, sector_size, dest + i, op);
}
}
template class AESCipher<Key128>;
template class AESCipher<Key256>;
} // namespace Core::Crypto