KeyChainUtilities.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
// HEADER_UNIT_UNSUPPORTED - Includes JsonSerializer.h which is not in Core module
 
#include "Base64.h"
#include "CoreDelegates.h"
#include "CoreMinimal.h"
#include "HAL/FileManager.h"
#include "IEngineCrypto.h"
#include "NamedAESKey.h"
#include "RSA.h"
#include "Serialization/Archive.h"
#include "Serialization/JsonSerializer.h"
 
struct FKeyChain
{
public:
 
    FKeyChain() = default;
 
    FKeyChain(const FKeyChain& Other)
    {
        SetSigningKey(Other.GetSigningKey());
        SetEncryptionKeys(Other.GetEncryptionKeys());
 
        if (Other.GetPrincipalEncryptionKey())
        {
            SetPrincipalEncryptionKey(GetEncryptionKeys().Find(Other.GetPrincipalEncryptionKey()->Guid));
        }
    }
    
    FKeyChain(FKeyChain&& Other)
    {
        SetSigningKey(Other.GetSigningKey());
        SetEncryptionKeys(MoveTemp(Other.GetEncryptionKeys()));
 
        if (Other.GetPrincipalEncryptionKey())
        {
            SetPrincipalEncryptionKey(GetEncryptionKeys().Find(Other.GetPrincipalEncryptionKey()->Guid));
        }
        
        Other.SetSigningKey(InvalidRSAKeyHandle);
        Other.SetPrincipalEncryptionKey(nullptr);
        Other.SetEncryptionKeys(TMap<FGuid, FNamedAESKey>());
    }
 
    FKeyChain& operator=(const FKeyChain& Other)
    {
        SetSigningKey(Other.GetSigningKey());
        SetEncryptionKeys(Other.GetEncryptionKeys());
        
        if (Other.GetPrincipalEncryptionKey())
        {
            SetPrincipalEncryptionKey(GetEncryptionKeys().Find(Other.GetPrincipalEncryptionKey()->Guid));
        }
        else
        {
            SetPrincipalEncryptionKey(nullptr);
        }
 
        return *this;
    }
 
    FKeyChain& operator=(FKeyChain&& Other)
    {
        SetSigningKey(Other.GetSigningKey());
        SetEncryptionKeys(MoveTemp(Other.GetEncryptionKeys()));
        
        if (Other.GetPrincipalEncryptionKey())
        {
            SetPrincipalEncryptionKey(GetEncryptionKeys().Find(Other.GetPrincipalEncryptionKey()->Guid));
        }
        else
        {
            SetPrincipalEncryptionKey(nullptr);
        }
 
        Other.SetSigningKey(InvalidRSAKeyHandle);
        Other.SetPrincipalEncryptionKey(nullptr);
        Other.SetEncryptionKeys(TMap<FGuid, FNamedAESKey>());
 
        return *this;
    }
 
    PRAGMA_DISABLE_DEPRECATION_WARNINGS
    FRSAKeyHandle GetSigningKey() const { return SigningKey; }
    void SetSigningKey(FRSAKeyHandle key) { SigningKey = key; }
 
    const FNamedAESKey* GetPrincipalEncryptionKey() const { return MasterEncryptionKey; }
    void SetPrincipalEncryptionKey(const FNamedAESKey* key) { MasterEncryptionKey =key; }
 
    const TMap<FGuid, FNamedAESKey>& GetEncryptionKeys() const { return EncryptionKeys; }
    TMap<FGuid, FNamedAESKey>& GetEncryptionKeys() { return EncryptionKeys; }
 
    void SetEncryptionKeys(const TMap<FGuid, FNamedAESKey>& keys) { EncryptionKeys = keys; }
    PRAGMA_ENABLE_DEPRECATION_WARNINGS
 
    UE_DEPRECATED(5.1, "Use Get/SetSigningKey instead")
    FRSAKeyHandle SigningKey = InvalidRSAKeyHandle;
 
    UE_DEPRECATED(5.1, "Use GetEncryptionKeys instead")
    TMap<FGuid, FNamedAESKey> EncryptionKeys;
    
    UE_DEPRECATED(5.1, "Use Get/SetPrincipalEncryptionKey instead")
    const FNamedAESKey* MasterEncryptionKey = nullptr;
};
 
 
namespace KeyChainUtilities
{
    static FRSAKeyHandle ParseRSAKeyFromJson(TSharedPtr<FJsonObject> InObj)
    {
        TSharedPtr<FJsonObject> PublicKey = InObj->GetObjectField(TEXT("PublicKey"));
        TSharedPtr<FJsonObject> PrivateKey = InObj->GetObjectField(TEXT("PrivateKey"));
 
        FString PublicExponentBase64, PrivateExponentBase64, PublicModulusBase64, PrivateModulusBase64;
 
        if (PublicKey->TryGetStringField(TEXT("Exponent"), PublicExponentBase64)
            && PublicKey->TryGetStringField(TEXT("Modulus"), PublicModulusBase64)
            && PrivateKey->TryGetStringField(TEXT("Exponent"), PrivateExponentBase64)
            && PrivateKey->TryGetStringField(TEXT("Modulus"), PrivateModulusBase64))
        {
            check(PublicModulusBase64 == PrivateModulusBase64);
 
            TArray<uint8> PublicExponent, PrivateExponent, Modulus;
            FBase64::Decode(PublicExponentBase64, PublicExponent);
            FBase64::Decode(PrivateExponentBase64, PrivateExponent);
            FBase64::Decode(PublicModulusBase64, Modulus);
 
            return FRSA::CreateKey(PublicExponent, PrivateExponent, Modulus);
        }
        else
        {
            return nullptr;
        }
    }
 
    static void LoadKeyChainFromFile(const FString& InFilename, FKeyChain& OutCryptoSettings)
    {
        FArchive* File = IFileManager::Get().CreateFileReader(*InFilename);
        checkf(File != nullptr, TEXT("Specified crypto keys cache '%s' does not exist!"), *InFilename);
        TSharedPtr<FJsonObject> RootObject;
        TSharedRef<TJsonReader<UTF8CHAR>> Reader = TJsonReaderFactory<UTF8CHAR>::Create(File);
        if (FJsonSerializer::Deserialize(Reader, RootObject))
        {
            const TSharedPtr<FJsonObject>* EncryptionKeyObject;
            if (RootObject->TryGetObjectField(TEXT("EncryptionKey"), EncryptionKeyObject))
            {
                FString EncryptionKeyBase64;
                if ((*EncryptionKeyObject)->TryGetStringField(TEXT("Key"), EncryptionKeyBase64))
                {
                    if (EncryptionKeyBase64.Len() > 0)
                    {
                        TArray<uint8> Key;
                        FBase64::Decode(EncryptionKeyBase64, Key);
                        check(Key.Num() == sizeof(FAES::FAESKey::Key));
                        FNamedAESKey NewKey;
                        NewKey.Name = TEXT("Default");
                        NewKey.Guid = FGuid();
                        FMemory::Memcpy(NewKey.Key.Key, &Key[0], sizeof(FAES::FAESKey::Key));
                        OutCryptoSettings.GetEncryptionKeys().Add(NewKey.Guid, NewKey);
                    }
                }
            }
 
            const TSharedPtr<FJsonObject>* SigningKey = nullptr;
            if (RootObject->TryGetObjectField(TEXT("SigningKey"), SigningKey))
            {
                OutCryptoSettings.SetSigningKey(ParseRSAKeyFromJson(*SigningKey));
            }
 
            const TArray<TSharedPtr<FJsonValue>>* SecondaryEncryptionKeyArray = nullptr;
            if (RootObject->TryGetArrayField(TEXT("SecondaryEncryptionKeys"), SecondaryEncryptionKeyArray))
            {
                for (TSharedPtr<FJsonValue> EncryptionKeyValue : *SecondaryEncryptionKeyArray)
                {
                    FNamedAESKey NewKey;
                    TSharedPtr<FJsonObject> SecondaryEncryptionKeyObject = EncryptionKeyValue->AsObject();
                    FGuid::Parse(SecondaryEncryptionKeyObject->GetStringField(TEXT("Guid")), NewKey.Guid);
                    NewKey.Name = SecondaryEncryptionKeyObject->GetStringField(TEXT("Name"));
                    FString KeyBase64 = SecondaryEncryptionKeyObject->GetStringField(TEXT("Key"));
 
                    TArray<uint8> Key;
                    FBase64::Decode(KeyBase64, Key);
                    check(Key.Num() == sizeof(FAES::FAESKey::Key));
                    FMemory::Memcpy(NewKey.Key.Key, &Key[0], sizeof(FAES::FAESKey::Key));
 
                    check(!OutCryptoSettings.GetEncryptionKeys().Contains(NewKey.Guid) || OutCryptoSettings.GetEncryptionKeys()[NewKey.Guid].Key == NewKey.Key);
                    OutCryptoSettings.GetEncryptionKeys().Add(NewKey.Guid, NewKey);
                }
            }
        }
        delete File;
        FGuid EncryptionKeyOverrideGuid;
        OutCryptoSettings.SetPrincipalEncryptionKey(OutCryptoSettings.GetEncryptionKeys().Find(EncryptionKeyOverrideGuid));
    }
 
    static void ApplyEncryptionKeys(const FKeyChain& KeyChain)
    {
        if (KeyChain.GetEncryptionKeys().Contains(FGuid()))
        {
            FAES::FAESKey DefaultKey = KeyChain.GetEncryptionKeys()[FGuid()].Key;
            FCoreDelegates::GetPakEncryptionKeyDelegate().BindLambda([DefaultKey](uint8 OutKey[32]) { FMemory::Memcpy(OutKey, DefaultKey.Key, sizeof(DefaultKey.Key)); });
        }
 
        for (const TMap<FGuid, FNamedAESKey>::ElementType& Key : KeyChain.GetEncryptionKeys())
        {
            if (Key.Key.IsValid())
            {
                FCoreDelegates::GetRegisterEncryptionKeyMulticastDelegate().Broadcast(Key.Key, Key.Value.Key);
            }
        }
    }
}