Шифрование и дешифрование файла XML

Question

Я хочу зашифровать XML-файл и расшифровать его на другой машине в C#. Пожалуйста, помогите ......

Я уже пробовал с RSA-алгоритмом и RijndaelManaged ключом, но не смог расшифровать файл на другой машине.

Answer 1

Из описания проблемы вы, вероятно, смотрите на симметричный алгоритм шифрования. Это то, что поможет вам начать:

public class Key { 
    public string Password { get; set; } 
    public byte[] Salt { get; set; } 
    public string Vector { get; set; } 
    public PaddingMode? Padding { get; set; } 
} 

public class AesCryptor { 
    private const int HASH_SIZE = 32; 
    private ICryptoTransform m_Decryptor; 
    private ICryptoTransform m_Encryptor; 
    private TimeSpan m_Validity; 

    // Methods 
    public AesCryptor(Key key, TimeSpan validity) { 
    if (key == null) { 
     throw new ArgumentNullException("key"); 
    } 
    m_Validity = validity; 
    using (AesManaged aes = new AesManaged()) { 
     aes.Mode = CipherMode.CBC; 
     aes.Key = new Rfc2898DeriveBytes(key.Password, key.Salt).GetBytes(aes.KeySize/8); 
     aes.IV = Encoding.ASCII.GetBytes(key.Vector); 
     if (key.Padding.HasValue) { 
     aes.Padding = key.Padding.Value; 
     } 
     m_Encryptor = aes.CreateEncryptor(); 
     m_Decryptor = aes.CreateDecryptor(); 
    } 
    } 

    private static bool CompareArray(byte[] first, byte[] second) { 
    if (first.Length != second.Length) { 
     return false; 
    } 
    for (int i = 0; i < first.Length; i++) { 
     if (first[i] != second[i]) { 
     return false; 
     } 
    } 
    return true; 
    } 

    public byte[] Decrypt(byte[] encryptedData) { 
    byte[] hash; 
    if (encryptedData == null) { 
     throw new ArgumentNullException("encryptedData"); 
    } 
    byte[] buffer = m_Decryptor.TransformFinalBlock(encryptedData, 0, encryptedData.Length); 
    using (SHA256 sha = SHA256.Create()) { 
     hash = sha.ComputeHash(buffer, 0, buffer.Length - HASH_SIZE); 
    } 
    byte[] orginalHash = new byte[HASH_SIZE]; 
    Buffer.BlockCopy(buffer, buffer.Length - HASH_SIZE, orginalHash, 0, HASH_SIZE); 
    if (!CompareArray(orginalHash, hash)) { 
     throw new Exception("Hash match failure."); 
    } 
    if (m_Validity != TimeSpan.Zero) { 
     DateTime timestamp = new DateTime(BitConverter.ToInt64(buffer, (buffer.Length - HASH_SIZE) - 8)); 
     TimeSpan delta = (TimeSpan)(DateTime.Now - timestamp); 
     if (delta > m_Validity) { 
     throw new Exception("Timestamp too old."); 
     } 
    } 
    byte[] result = new byte[(buffer.Length - HASH_SIZE) - 8]; 
    Buffer.BlockCopy(buffer, 0, result, 0, (buffer.Length - HASH_SIZE) - 8); 
    return result; 
    } 

    public byte[] Encrypt(byte[] data) { 
    byte[] hash; 
    if (data == null) { 
     throw new ArgumentNullException("data"); 
    } 
    byte[] buffer = new byte[(data.Length + 8) + HASH_SIZE]; 
    Buffer.BlockCopy(data, 0, buffer, 0, data.Length); 
    Buffer.BlockCopy(BitConverter.GetBytes(DateTime.Now.Ticks), 0, buffer, data.Length, 8); 
    using (SHA256 sha = SHA256.Create()) { 
     hash = sha.ComputeHash(buffer, 0, buffer.Length - HASH_SIZE); 
    } 
    Buffer.BlockCopy(hash, 0, buffer, buffer.Length - HASH_SIZE, HASH_SIZE); 
    return m_Encryptor.TransformFinalBlock(buffer, 0, buffer.Length); 
    } 
} 

Использование:

var myKey = new Key { 
    Password = "whatever,nevermind@$", 
    Vector = "Q^!#g1353hdhjs*-", 
    Salt = new byte[] { 0x33, 0x4d, 0x56, 0x4f, 1, 0x22, 15, 0x7f } 
    }; 
    var cryptor = new AesCryptor(myKey, TimeSpan.Zero); 
    // this will encrypt c:\test.xml into byte array 
    byte[] encrypted = cryptor.Encrypt(File.ReadAllBytes(@"c:\test.xml")); 
    // this will persist encrypted byte array into file c:\test-encrypted.bin 
    File.WriteAllBytes(@"c:\test-encrypted.bin", encrypted); 
    // this will load & decrypt bytes from file c:\test-encrypted.bin 
    byte[] decrypted = cryptor.Decrypt(File.ReadAllBytes(@"c:\test-encrypted.bin")); 
    // this will write decrypted bytes into c:\test-decrypted.xml 
    File.WriteAllBytes(@"c:\test-decrypted.xml", decrypted);