public ContainerWriter(Stream writeStream, string fileName, X509Certificate2 certificate)
{
this.writeStream = writeStream ?? throw new ArgumentNullException(nameof(writeStream));
this.fileName = fileName ?? throw new ArgumentNullException(nameof(writeStream));
FileNameHelper.CheckFileName(fileName, nameof(fileName));
this.aes = new AesManaged();
this.aes.Mode = CipherMode.CBC;
this.aes.Padding = PaddingMode.PKCS7;
this.aes.KeySize = 256;
this.aes.BlockSize = 128;
this.randomSource = new Random(Guid.NewGuid().GetHashCode());
this.aes.GenerateKey();
this.aes.GenerateIV();
this.header = new ContainerHeader();
this.header.CertificateThumbprint = certificate.Thumbprint;
this.header.EncryptedDataSize = 0L;
this.header.KeyType = this.GetKeyType(certificate.GetRSAPublicKey());
this.header.EncryptedKey = certificate.GetRSAPublicKey().Encrypt(this.aes.Key, RSAEncryptionPadding.Pkcs1); //RSA Padding
this.header.InitializeVector = this.aes.IV;
this.encryptor = this.aes.CreateEncryptor();
this.headerWrited = false;
this.AdditionalPadingSize = (uint)this.randomSource.Next(512, 2048);
}
public async Task <string> ReadFileName()
{
if (this.fileName != null)
{
return(this.fileName);
}
ContainerHeader header = await ContainerHeader.ReadFromStream(this.readerStream);
byte[]? aesKey = null;
try
{
aesKey = await this.cryptoAccessor.AsymetricDecrypt(header.CertificateThumbprint, header.EncryptedKey, RSAEncryptionPadding.Pkcs1); //RSA Padding
this.aesDecryptor = this.aes.CreateDecryptor(aesKey, header.InitializeVector);
this.cryptoStream = new CryptoStream(this.readerStream, this.aesDecryptor, CryptoStreamMode.Read);
using (BinaryDataStream bds = new BinaryDataStream(this.cryptoStream, false))
{
//TODO: Optimalization
for (uint i = 0; i < 16; i++)
{
bds.ReadByte();
}
uint randomDataSize = await bds.Read4BitNumber();
uint stringLen = await bds.Read4BitNumber();
//TODO: Optimalization
for (uint i = 0; i < randomDataSize; i++)
{
bds.ReadByte();
}
string fileName = await bds.ReadConstatntString((int)stringLen, Encoding.UTF8);
FileNameHelper.CheckFileName(fileName, nameof(fileName));
this.fileName = fileName;
return(fileName);
}
}
finally
{
if (aesKey != null)
{
for (int i = 0; i < aesKey.Length; i++)
{
aesKey[i] = 0x00;
aesKey[i] = 0xFF;
}
}
}
}
public void TestCheckFileName()
{
Assert.True(FileNameHelper.CheckFileName("myDirectory"));
Assert.True(FileNameHelper.CheckFileName("myTextFile.txt"));
Assert.False(FileNameHelper.CheckFileName(""));
Assert.False(FileNameHelper.CheckFileName(null));
Assert.False(FileNameHelper.CheckFileName("t_<_.txt"));
Assert.False(FileNameHelper.CheckFileName("t_>_.txt"));
Assert.False(FileNameHelper.CheckFileName("t_:_.txt"));
Assert.False(FileNameHelper.CheckFileName("t_\"_.txt"));
Assert.False(FileNameHelper.CheckFileName("t_/_.txt"));
Assert.False(FileNameHelper.CheckFileName("t_\\_.txt"));
Assert.False(FileNameHelper.CheckFileName("t_|_.txt"));
Assert.False(FileNameHelper.CheckFileName("t_?_.txt"));
Assert.False(FileNameHelper.CheckFileName("t_*_.txt"));
}