private static void DecryptFile(string storage, string fullInfoFilePath)
{
// load parameters
var secret = SecretData.Deserialize(fullInfoFilePath);
var basePath = Path.GetDirectoryName(fullInfoFilePath);
var decryptedFullFileName = Path.Combine(basePath, secret.DecryptedFileName);
byte[] iv1 = Convert.FromBase64String(secret.IV1);
byte[] key1 = Convert.FromBase64String(secret.Key1);
byte[] iv2 = Convert.FromBase64String(secret.IV2);
byte[] key2 = Convert.FromBase64String(secret.Key2);
HashAlgorithm decryptedHashAlg, encryptedHashAlg;
GetHashAlgorithms(out decryptedHashAlg, out encryptedHashAlg);
try
{
using (FileStream decryptedFileStream = new FileStream(decryptedFullFileName, FileMode.Create))
using (CryptoStream decryptedHashStream = new CryptoStream(decryptedFileStream, decryptedHashAlg, CryptoStreamMode.Write))
using (CryptoStream decryptor1 = new CryptoStream(decryptedHashStream, new RijndaelManaged {
KeySize = keySize
}.CreateDecryptor(key1, iv1), CryptoStreamMode.Write))
using (CryptoStream decryptor2 = new CryptoStream(decryptor1, new RijndaelManaged {
KeySize = keySize
}.CreateDecryptor(key2, iv2), CryptoStreamMode.Write))
using (CryptoStream encryptedHashStream = new CryptoStream(decryptor2, encryptedHashAlg, CryptoStreamMode.Write))
{
var backupStorage = GetBackupStorage(storage, basePath);
backupStorage.Download(secret.EncryptedFileName, encryptedHashStream);
}
if (secret.DecryptedMD5 != Convert.ToBase64String(decryptedHashAlg.Hash))
{
throw new InvalidDataException("Decrypted hash mismatch");
}
if (secret.EncryptedMD5 != Convert.ToBase64String(encryptedHashAlg.Hash))
{
throw new InvalidDataException("Encrypted hash mismatch");
}
}
catch
{
try
{
if (File.Exists(decryptedFullFileName))
{
File.Delete(decryptedFullFileName);
}
}
catch { /* we just trying to cleanup, but probably better processing required...*/ }
throw;
}
}
private static void Encrypt(string storage, string decryptedFullFilePath, string password1, string password2)
{
var secret = new SecretData();
// generate a 128-bit salt and IV using a secure PRNG
byte[] iv1 = new byte[ivSize / 8];
byte[] salt1 = new byte[ivSize / 8];
byte[] key1;
byte[] iv2 = new byte[ivSize / 8];
byte[] salt2 = new byte[ivSize / 8];
byte[] key2;
var randomFileName = new byte[ivSize / 8];
// generate key`s
using (var rng = RandomNumberGenerator.Create())
using (var kd1 = new Rfc2898DeriveBytes(password1, salt1, 10000 + salt1[0] + salt1[1] + salt1[2] + salt1[3]))
using (var kd2 = new Rfc2898DeriveBytes(password2, salt2, 10000 + salt2[4] + salt2[5] + salt2[6] + salt2[7]))
{
rng.GetBytes(iv1);
rng.GetBytes(salt1);
rng.GetBytes(iv2);
rng.GetBytes(salt2);
rng.GetBytes(randomFileName);
key1 = kd1.GetBytes(keySize / 8);
key2 = kd2.GetBytes(keySize / 8);
//byte[] key1 = Microsoft.AspNetCore.Cryptography.KeyDerivationKeyDerivation.Pbkdf2(password1, salt1, KeyDerivationPrf.HMACSHA512, 10000 + salt1[0] + salt1[1] + salt1[2] + salt1[3], keySize / 8);
//byte[] key2 = Microsoft.AspNetCore.Cryptography.KeyDerivationKeyDerivation.Pbkdf2(password2, salt2, KeyDerivationPrf.HMACSHA512, 10000 + salt2[4] + salt2[5] + salt2[6] + salt2[7], keySize / 8);
}
// prepare
secret.IV1 = Convert.ToBase64String(iv1);
secret.Key1 = Convert.ToBase64String(key1);
secret.IV2 = Convert.ToBase64String(iv2);
secret.Key2 = Convert.ToBase64String(key2);
secret.DecryptedFileName = Path.GetFileName(decryptedFullFilePath);
//secret.EncryptedFileName = Guid.NewGuid().ToString("N"); // may disclouse information about TimeStamp and PC MAC address
secret.EncryptedFileName = BitConverter.ToString(randomFileName).Replace("-", string.Empty);
var baseFolder = Path.GetDirectoryName(decryptedFullFilePath);
HashAlgorithm decryptedHashAlg, encryptedHashAlg;
GetHashAlgorithms(out decryptedHashAlg, out encryptedHashAlg);
using (FileStream decryptedFileStream = new FileStream(decryptedFullFilePath, FileMode.Open))
using (CryptoStream decryptedHashStream = new CryptoStream(decryptedFileStream, decryptedHashAlg, CryptoStreamMode.Read))
using (CryptoStream encryptor1 = new CryptoStream(decryptedHashStream, new RijndaelManaged {
KeySize = keySize
}.CreateEncryptor(key1, iv1), CryptoStreamMode.Read))
using (CryptoStream encryptor2 = new CryptoStream(encryptor1, new RijndaelManaged {
KeySize = keySize
}.CreateEncryptor(key2, iv2), CryptoStreamMode.Read))
using (CryptoStream encryptedHashStream = new CryptoStream(encryptor2, encryptedHashAlg, CryptoStreamMode.Read))
{
var backupStorage = GetBackupStorage(storage, baseFolder);
if (backupStorage.ProgressReporter != null)
{
backupStorage.ProgressReporter.Init(decryptedFileStream.Length);
}
backupStorage.Upload(secret.EncryptedFileName, encryptedHashStream);
}
secret.DecryptedMD5 = Convert.ToBase64String(decryptedHashAlg.Hash);
secret.EncryptedMD5 = Convert.ToBase64String(encryptedHashAlg.Hash);
secret.Serialize(decryptedFullFilePath + ".secret");
}
