Merge pull request #567 from wheremyfoodat/seed-crypto

Implement seed crypto

include/crypto/aes_engine.hpp

@@ -1,20 +1,29 @@
 #pragma once
 
 #include <array>
-#include <cstring>
-#include <cstdint>
 #include <climits>
+#include <cstdint>
+#include <cstring>
 #include <filesystem>
 #include <optional>
+#include <vector>
 
 #include "helpers.hpp"
+#include "io_file.hpp"
+#include "swap.hpp"
 
 namespace Crypto {
-	constexpr std::size_t AesKeySize = 0x10;
+	constexpr usize AesKeySize = 0x10;
 	using AESKey = std::array<u8, AesKeySize>;
 
-	template <std::size_t N>
+	struct Seed {
-	static std::array<u8, N> rolArray(const std::array<u8, N>& value, std::size_t bits) {
+		u64_le titleID;
+		AESKey seed;
+		std::array<u8, 8> pad;
+	};
+
+	template <usize N>
+	static std::array<u8, N> rolArray(const std::array<u8, N>& value, usize bits) {
 		const auto bitWidth = N * CHAR_BIT;
 
 		bits %= bitWidth;
@@ -24,18 +33,18 @@ namespace Crypto {
 
 		std::array<u8, N> result;
 
-		for (std::size_t i = 0; i < N; i++) {
+		for (usize i = 0; i < N; i++) {
 			result[i] = ((value[(i + byteShift) % N] << bitShift) | (value[(i + byteShift + 1) % N] >> (CHAR_BIT - bitShift))) & UINT8_MAX;
 		}
 
 		return result;
 	}
 
-	template <std::size_t N>
+	template <usize N>
 	static std::array<u8, N> addArray(const std::array<u8, N>& a, const std::array<u8, N>& b) {
 		std::array<u8, N> result;
-		std::size_t sum = 0;
+		usize sum = 0;
-		std::size_t carry = 0;
+		usize carry = 0;
 
 		for (std::int64_t i = N - 1; i >= 0; i--) {
 			sum = a[i] + b[i] + carry;
@@ -46,11 +55,11 @@ namespace Crypto {
 		return result;
 	}
 
-	template <std::size_t N>
+	template <usize N>
 	static std::array<u8, N> xorArray(const std::array<u8, N>& a, const std::array<u8, N>& b) {
 		std::array<u8, N> result;
 
-		for (std::size_t i = 0; i < N; i++) {
+		for (usize i = 0; i < N; i++) {
 			result[i] = a[i] ^ b[i];
 		}
 
@@ -63,7 +72,7 @@ namespace Crypto {
 		}
 
 		AESKey rawKey;
-		for (std::size_t i = 0; i < rawKey.size(); i++) {
+		for (usize i = 0; i < rawKey.size(); i++) {
 			rawKey[i] = static_cast<u8>(std::stoi(hex.substr(i * 2, 2), 0, 16));
 		}
 
@@ -76,7 +85,7 @@ namespace Crypto {
 		std::optional<AESKey> normalKey = std::nullopt;
 	};
 
-	enum KeySlotId : std::size_t {
+	enum KeySlotId : usize {
 		NCCHKey0 = 0x2C,
 		NCCHKey1 = 0x25,
 		NCCHKey2 = 0x18,
@@ -84,14 +93,17 @@ namespace Crypto {
 	};
 
 	class AESEngine {
-	private:
+	  private:
-		constexpr static std::size_t AesKeySlotCount = 0x40;
+		constexpr static usize AesKeySlotCount = 0x40;
 
 		std::optional<AESKey> m_generator = std::nullopt;
 		std::array<AESKeySlot, AesKeySlotCount> m_slots;
 		bool keysLoaded = false;
 
-		constexpr void updateNormalKey(std::size_t slotId) {
+		std::vector<Seed> seeds;
+		IOFile seedDatabase;
+
+		constexpr void updateNormalKey(usize slotId) {
 			if (m_generator.has_value() && hasKeyX(slotId) && hasKeyY(slotId)) {
 				auto& keySlot = m_slots.at(slotId);
 				AESKey keyX = keySlot.keyX.value();
@@ -101,13 +113,17 @@ namespace Crypto {
 			}
 		}
 
-	public:
+	  public:
 		AESEngine() {}
 		void loadKeys(const std::filesystem::path& path);
+		void setSeedPath(const std::filesystem::path& path);
+		// Returns true on success, false on failure
+		bool loadSeeds();
+
 		bool haveKeys() { return keysLoaded; }
 		bool haveGenerator() { return m_generator.has_value(); }
 
-		constexpr bool hasKeyX(std::size_t slotId) {
+		constexpr bool hasKeyX(usize slotId) {
 			if (slotId >= AesKeySlotCount) {
 				return false;
 			}
@@ -115,18 +131,16 @@ namespace Crypto {
 			return m_slots.at(slotId).keyX.has_value();
 		}
 
-		constexpr AESKey getKeyX(std::size_t slotId) {
+		constexpr AESKey getKeyX(usize slotId) { return m_slots.at(slotId).keyX.value_or(AESKey{}); }
-			return m_slots.at(slotId).keyX.value_or(AESKey{});
-		}
 
-		constexpr void setKeyX(std::size_t slotId, const AESKey &key) {
+		constexpr void setKeyX(usize slotId, const AESKey& key) {
 			if (slotId < AesKeySlotCount) {
 				m_slots.at(slotId).keyX = key;
 				updateNormalKey(slotId);
 			}
 		}
 
-		constexpr bool hasKeyY(std::size_t slotId) {
+		constexpr bool hasKeyY(usize slotId) {
 			if (slotId >= AesKeySlotCount) {
 				return false;
 			}
@@ -134,18 +148,16 @@ namespace Crypto {
 			return m_slots.at(slotId).keyY.has_value();
 		}
 
-		constexpr AESKey getKeyY(std::size_t slotId) {
+		constexpr AESKey getKeyY(usize slotId) { return m_slots.at(slotId).keyY.value_or(AESKey{}); }
-			return m_slots.at(slotId).keyY.value_or(AESKey{});
-		}
 
-		constexpr void setKeyY(std::size_t slotId, const AESKey &key) {
+		constexpr void setKeyY(usize slotId, const AESKey& key) {
 			if (slotId < AesKeySlotCount) {
 				m_slots.at(slotId).keyY = key;
 				updateNormalKey(slotId);
 			}
 		}
 
-		constexpr bool hasNormalKey(std::size_t slotId) {
+		constexpr bool hasNormalKey(usize slotId) {
 			if (slotId >= AesKeySlotCount) {
 				return false;
 			}
@@ -153,14 +165,14 @@ namespace Crypto {
 			return m_slots.at(slotId).normalKey.has_value();
 		}
 
-		constexpr AESKey getNormalKey(std::size_t slotId) {
+		constexpr AESKey getNormalKey(usize slotId) { return m_slots.at(slotId).normalKey.value_or(AESKey{}); }
-			return m_slots.at(slotId).normalKey.value_or(AESKey{});
-		}
 
-		constexpr void setNormalKey(std::size_t slotId, const AESKey &key) {
+		constexpr void setNormalKey(usize slotId, const AESKey& key) {
 			if (slotId < AesKeySlotCount) {
 				m_slots.at(slotId).normalKey = key;
 			}
 		}
+
+		std::optional<AESKey> getSeedFromDB(u64 titleID);
 	};
-}
+}  // namespace Crypto

src/core/crypto/aes_engine.cpp

@@ -1,13 +1,15 @@
-#include <iostream>
-#include <fstream>
-
 #include "crypto/aes_engine.hpp"
+
+#include <fstream>
+#include <iostream>
+#include <tuple>
+
 #include "helpers.hpp"
 
 namespace Crypto {
 	void AESEngine::loadKeys(const std::filesystem::path& path) {
 		std::ifstream file(path, std::ios::in);
-	
+
 		if (file.fail()) {
 			Helpers::warn("Keys: Couldn't read key file: %s", path.c_str());
 			return;
@@ -58,18 +60,10 @@ namespace Crypto {
 			}
 
 			switch (keyType) {
-				case 'X':
+				case 'X': setKeyX(slotId, key.value()); break;
-					setKeyX(slotId, key.value());
+				case 'Y': setKeyY(slotId, key.value()); break;
-					break;
+				case 'N': setNormalKey(slotId, key.value()); break;
-				case 'Y':
+				default: Helpers::warn("Keys: Invalid key type %c", keyType); break;
-					setKeyY(slotId, key.value());
-					break;
-				case 'N':
-					setNormalKey(slotId, key.value());
-					break;
-				default:
-					Helpers::warn("Keys: Invalid key type %c", keyType);
-					break;
 			}
 		}
 
@@ -80,4 +74,65 @@ namespace Crypto {
 
 		keysLoaded = true;
 	}
-};
+
+	void AESEngine::setSeedPath(const std::filesystem::path& path) { seedDatabase.open(path, "rb"); }
+
+	// Loads seeds from a seed file, return true on success and false on failure
+	bool AESEngine::loadSeeds() {
+		if (!seedDatabase.isOpen()) {
+			return false;
+		}
+
+		// The # of seeds is stored at offset 0
+		u32_le seedCount = 0;
+
+		if (!seedDatabase.rewind()) {
+			return false;
+		}
+
+		auto [success, size] = seedDatabase.readBytes(&seedCount, sizeof(u32));
+		if (!success || size != sizeof(u32)) {
+			return false;
+		}
+
+		// Key data starts from offset 16
+		if (!seedDatabase.seek(16)) {
+			return false;
+		}
+
+		Crypto::Seed seed;
+		for (uint i = 0; i < seedCount; i++) {
+			std::tie(success, size) = seedDatabase.readBytes(&seed, sizeof(seed));
+			if (!success || size != sizeof(seed)) {
+				return false;
+			}
+
+			seeds.push_back(seed);
+		}
+
+		return true;
+	}
+
+	std::optional<Crypto::AESKey> AESEngine::getSeedFromDB(u64 titleID) {
+		// We don't have a seed db nor any seeds loaded, return nullopt
+		if (!seedDatabase.isOpen() && seeds.empty()) {
+			return std::nullopt;
+		}
+
+		// We have a seed DB but haven't loaded the seeds yet, so load them
+		if (seedDatabase.isOpen() && seeds.empty()) {
+			bool success = loadSeeds();
+			if (!success) {
+				return std::nullopt;
+			}
+		}
+
+		for (Crypto::Seed& seed : seeds) {
+			if (seed.titleID == titleID) {
+				return seed.seed;
+			}
+		}
+
+		return std::nullopt;
+	}
+};  // namespace Crypto

src/core/loader/ncch.cpp

@@ -1,12 +1,15 @@
+#include "loader/ncch.hpp"
+
 #include <cryptopp/aes.h>
 #include <cryptopp/modes.h>
-#include <cstring>
+#include <cryptopp/sha.h>
-#include <vector>
-#include "loader/lz77.hpp"
-#include "loader/ncch.hpp"
-#include "memory.hpp"
 
+#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 +73,26 @@ bool NCCH::loadFromHeader(Crypto::AESEngine &aesEngine, IOFile& file, const FSIn
 		if (!seedCrypto) {
 			secondaryKeyY = primaryKeyY;
 		} else {
-			Helpers::warn("Seed crypto is not supported");
+			// 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
-			gotCryptoKeys = false;
+			// 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");
+				gotCryptoKeys = false;
+			}
 		}
 
 		auto primaryResult = getPrimaryKey(aesEngine, primaryKeyY);

src/emulator.cpp

@@ -220,6 +220,8 @@ bool Emulator::loadROM(const std::filesystem::path& path) {
 	const std::filesystem::path appDataPath = getAppDataRoot();
 	const std::filesystem::path dataPath = appDataPath / path.filename().stem();
 	const std::filesystem::path aesKeysPath = appDataPath / "sysdata" / "aes_keys.txt";
+	const std::filesystem::path seedDBPath = appDataPath / "sysdata" / "seeddb.bin";
+
 	IOFile::setAppDataDir(dataPath);
 
 	// Open the text file containing our AES keys if it exists. We use the std::filesystem::exists overload that takes an error code param to
@@ -229,6 +231,10 @@ bool Emulator::loadROM(const std::filesystem::path& path) {
 		aesEngine.loadKeys(aesKeysPath);
 	}
 
+	if (std::filesystem::exists(seedDBPath, ec) && !ec) {
+		aesEngine.setSeedPath(seedDBPath);
+	}
+
 	kernel.initializeFS();
 	auto extension = path.extension();
 	bool success;  // Tracks if we loaded the ROM successfully