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AES: Implement seed crypto

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wheremyfoodat 2024-07-30 14:29:18 +03:00
parent 908222f26f
commit f572373fc1
4 changed files with 151 additions and 57 deletions
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34
src/core/loader/ncch.cpp
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@ -1,12 +1,15 @@
#include "loader/ncch.hpp"
#include <cryptopp/aes.h>
#include <cryptopp/modes.h>
#include <cstring>
#include <vector>
#include "loader/lz77.hpp"
#include "loader/ncch.hpp"
#include "memory.hpp"
#include <cryptopp/sha.h>
#include <cstring>
#include <iostream>
#include <vector>
#include "loader/lz77.hpp"
#include "memory.hpp"
bool NCCH::loadFromHeader(Crypto::AESEngine &aesEngine, IOFile& file, const FSInfo &info) {
// 0x200 bytes for the NCCH header
@ -70,8 +73,25 @@ bool NCCH::loadFromHeader(Crypto::AESEngine &aesEngine, IOFile& file, const FSIn
if (!seedCrypto) {
secondaryKeyY = primaryKeyY;
} else {
Helpers::warn("Seed crypto is not supported");
gotCryptoKeys = false;
// In seed crypto mode, the secondary key is computed through a SHA256 hash of the primary key and a title-specific seed, which we fetch
// from seeddb.bin
std::optional<Crypto::AESKey> seedOptional = aesEngine.getSeedFromDB(programID);
if (seedOptional.has_value()) {
auto seed = *seedOptional;
CryptoPP::SHA256 shaEngine;
std::array<u8, 32> data;
std::array<u8, CryptoPP::SHA256::DIGESTSIZE> hash;
std::memcpy(&data[0], primaryKeyY.data(), primaryKeyY.size());
std::memcpy(&data[16], seed.data(), seed.size());
shaEngine.CalculateDigest(hash.data(), data.data(), data.size());
// Note that SHA256 will produce a 256-bit hash, while we only need 128 bits cause this is an AES key
// So the latter 16 bytes of the SHA256 are thrown out.
std::memcpy(secondaryKeyY.data(), hash.data(), secondaryKeyY.size());
} else {
Helpers::warn("Couldn't find a seed value for this title. Make sure you have a seeddb.bin file alongside your aes_keys.txt");
}
}
auto primaryResult = getPrimaryKey(aesEngine, primaryKeyY);