private Stream CreateXTSStream(File file, long?start = null, long?end = null)
{
var pub = CryptoUtil.GetCryptoPublicInfo(_cloud, file);
var key = CryptoUtil.GetCryptoKey(_cloud.Account.Credentials.PasswordCrypt, pub.Salt);
var xts = XtsAes256.Create(key, pub.IV);
long fileLength = file.OriginalSize;
long requestedOffset = start ?? 0;
long requestedEnd = end ?? fileLength;
long alignedOffset = requestedOffset / XTSSectorSize * XTSSectorSize;
long alignedEnd = requestedEnd % XTSBlockSize == 0
? requestedEnd
: (requestedEnd / XTSBlockSize + 1) * XTSBlockSize;
if (alignedEnd == 0)
{
alignedEnd = 16;
}
var downStream = _cloud.Account.RequestRepo.GetDownloadStream(file, alignedOffset, alignedEnd);
ulong startSector = (ulong)alignedOffset / XTSSectorSize;
int trimStart = (int)(requestedOffset - alignedOffset);
uint trimEnd = alignedEnd == fileLength
? file.ServiceInfo.CryptInfo.AlignBytes
: (uint)(alignedEnd - requestedEnd);
var xtsStream = new XTSReadOnlyStream(downStream, xts, XTSSectorSize, startSector, trimStart, trimEnd);
return(xtsStream);
}
private Stream GetCryptoStream(File file, FileUploadedDelegate onUploaded)
{
var info = CryptoUtil.GetCryptoKeyAndSalt(_cloud.Account.Credentials.PasswordCrypt);
var xts = XtsAes256.Create(info.Key, info.IV);
file.ServiceInfo.CryptInfo = new CryptInfo
{
PublicKey = new CryptoKeyInfo {
Salt = info.Salt, IV = info.IV
},
AlignBytes = (uint)(file.Size % XTSWriteOnlyStream.BlockSize != 0
? XTSWriteOnlyStream.BlockSize - file.Size % XTSWriteOnlyStream.BlockSize
: 0)
};
var size = file.OriginalSize % XTSWriteOnlyStream.BlockSize == 0
? file.OriginalSize.DefaultValue
: (file.OriginalSize / XTSWriteOnlyStream.BlockSize + 1) * XTSWriteOnlyStream.BlockSize;
var ustream = new SplittedUploadStream(file.FullPath, _cloud, size, false, file.ServiceInfo.CryptInfo);
if (onUploaded != null)
{
ustream.FileUploaded += onUploaded;
}
// ReSharper disable once RedundantArgumentDefaultValue
var encustream = new XTSWriteOnlyStream(ustream, xts, XTSWriteOnlyStream.DefaultSectorSize);
return(encustream);
}
protected override async Task InitMetadataImplAsync(CancellationToken cancel = default)
{
Memory <byte> firstSectorData = new byte[XtsAesMetaDataSize];
// ヘッダの読み込みを試行する
int readSize = await this.PhysicalReadAsync(0, firstSectorData, cancel);
if (readSize == XtsAesMetaDataSize)
{
var metaDataParseResult = TryParseMetaData(firstSectorData);
metaDataParseResult.ThrowIfException();
var metaData = metaDataParseResult.Value !;
// パスワード検査
if (Secure.VeritySaltedPassword(metaData.SaltedPassword, this.CurrentPassword) == false)
{
throw new CoresException("XtsAesRandomAccess: Incorrect password.");
}
// 秘密鍵解読
var decrypted = ChaChaPoly.EasyDecryptWithPassword(metaData.MasterKeyEncryptedByPassword._GetHexBytes(), this.CurrentPassword);
decrypted.ThrowIfException();
// 秘密鍵サイズ検査
if (decrypted.Value.Length != XtsAesKeySize)
{
throw new CoresException("XtsAesRandomAccess: decrypted.Value.Length != XtsAesKeySize");
}
this.CurrentMasterKey = decrypted.Value;
this.CurrentMetaData = metaData;
}
else if (readSize == 0)
{
// ファイルの内容が存在しない
// マスターキーを新規作成する
this.CurrentMasterKey = Secure.Rand(XtsAesKeySize);
// メタデータを新規作成する
var metaData = new XtsAesRandomAccessMetaData
{
Version = 1,
VirtualSize = 0,
SaltedPassword = Secure.SaltPassword(this.CurrentPassword),
MasterKeyEncryptedByPassword = ChaChaPoly.EasyEncryptWithPassword(this.CurrentMasterKey, this.CurrentPassword)._GetHexString(),
};
this.CurrentMetaData = metaData;
// メタデータを書き込みする
await WriteMetaDataAsync(cancel);
}
else
{
// 不正 ここには来ないはず
throw new CoresException($"XtsAesRandomAccess: Invalid readSize: {readSize}");
}
// XTS を作成
this.CurrentXts = XtsAes256.Create(this.CurrentMasterKey.ToArray());
this.CurrentEncrypter = this.CurrentXts.CreateEncryptor();
this.CurrentDescrypter = this.CurrentXts.CreateDecryptor();
}
