/// <summary>
/// Decrypt data using username private key.
/// </summary>
/// <param name="data">Data to decrypt(session key).</param>
/// <param name="username">Allowed user</param>
/// <param name="keyPharse">Key to decrypt private key</param>
/// <returns>Decrypted data.</returns>
public static byte[] Decrypte(byte[] data, string username, byte[] keyPharse)
{
var rsa = new RSACryptoServiceProvider(Const.KEY_SIZE);
string privatePath = Path.Combine(Const.KEY_FOLDER_PATH, Const.PRIVATE_KEY_FOLDER, username);
string privateKeyFile = Path.Combine(privatePath, Const.PRIVATE_KEY_FILENAME);
if (!File.Exists(privateKeyFile))
{
throw new Exception("No user key");
}
try
{
using (var inputStream = File.OpenRead(privateKeyFile))
{
var aes = new AesEncryptionApi(CipherMode.CBC, 128, 256, keyPharse);
using (var streamdecrypted = aes.DecrypteStream(inputStream))
{
using (var input = new StreamReader(streamdecrypted))
{
string inputText = input.ReadToEnd();
rsa.FromXmlString(inputText);
}
}
}
}
catch (Exception)
{
throw new Exception("Wrong keypharse");
}
return(rsa.Decrypt(data, true));
}
/// <summary>
/// Reads the header and prepare Aes algorithm.
/// </summary>
/// <param name="inputPath">Encrypted file</param>
/// <param name="user">Authorized User</param>
/// <returns>Object of type <c>AesEncryptionApi</c> deserilized from file.</returns>
public static AesEncryptionApi FromXml(XmlReader reader)
{
var aes = new AesEncryptionApi();
reader.ReadToFollowing("KeySize");
aes.keySize = reader.ReadElementContentAsInt();
aes.blockSize = reader.ReadElementContentAsInt();
aes.cipherMode = Conversion.CipherFromString(reader.ReadElementContentAsString());
aes.iV = Conversion.ByteArrayFromString(reader.ReadElementContentAsString());
do
{
if (reader.NodeType == XmlNodeType.Element && reader.Name == "User")
{
var user = User.FromXml(reader);
aes.userList.Add(user);
}
else if (reader.NodeType == XmlNodeType.EndElement && reader.Name == "Header")
{
break;
}
}while (reader.Read());
return(aes);
}
/// <summary>
/// Generate key and save it.
/// </summary>
/// <param name="username">Name of the key owner.</param>
/// <param name="keyPharse">Key to encrypt private key</param>
public static void GenerateKey(string username, byte[] keyPharse)
{
var rsa = new RSACryptoServiceProvider(4096);
string publicPath = Path.Combine(Const.KEY_FOLDER_PATH, Const.PUBLIC_KEY_FOLDER, username);
string privatePath = Path.Combine(Const.KEY_FOLDER_PATH, Const.PRIVATE_KEY_FOLDER, username);
string publicKeyFile = Path.Combine(publicPath, Const.PUBLIC_KEY_FILENAME);
string privateKeyFile = Path.Combine(privatePath, Const.PRIVATE_KEY_FILENAME);
if (Directory.Exists(publicPath))
{
Directory.Delete(publicPath, true);
}
if (Directory.Exists(privatePath))
{
Directory.Delete(privatePath, true);
}
Directory.CreateDirectory(publicPath);
Directory.CreateDirectory(privatePath);
using (var file = new StreamWriter(publicKeyFile))
{
string publicKey = rsa.ToXmlString(false);
file.Write(publicKey);
}
using (var file = File.OpenWrite(privateKeyFile))
{
var aes = new AesEncryptionApi(CipherMode.CBC, 128, 256, keyPharse);
using (var fileOutput = aes.EncrypteStream(file, CryptoStreamMode.Write))
{
using (var output = new StreamWriter(fileOutput))
{
string privateKey = rsa.ToXmlString(true);
output.Write(privateKey);
}
}
}
}
