Paste these methods in your Utils class or other and use them as is to encrypt and decrypt your
strings or byte[]s. The session key is derived from the password you supply. This works on any machine with .Net 1.1+ so you can encrypt on one machine and decrypt on another as needed. Only the same password must be used to decrypt:
/// <summary>
/// Use AES to encrypt data string. The output string is the encrypted bytes as a base64 string.
/// The same password must be used to decrypt the string.
/// </summary>
/// <param name="data">Clear string to encrypt.</param>
/// <param name="password">Password used to encrypt the string.</param>
/// <returns>Encrypted result as Base64 string.</returns>
public static string EncryptData(string data, string password)
{
if ( data == null )
throw new ArgumentNullException("data");
if ( password == null )
throw new ArgumentNullException("password");
byte[] encBytes = EncryptData(Encoding.UTF8.GetBytes(data), password, PaddingMode.ISO10126);
return Convert.ToBase64String(encBytes);
}
/// <summary>
/// Decrypt the data string to the original string. The data must be the base64 string
/// returned from the EncryptData method.
/// </summary>
/// <param name="data">Encrypted data generated from EncryptData method.</param>
/// <param name="password">Password used to decrypt the string.</param>
/// <returns>Decrypted string.</returns>
public static string DecryptData(string data, string password)
{
if ( data == null )
throw new ArgumentNullException("data");
if ( password == null )
throw new ArgumentNullException("password");
byte[] encBytes = Convert.FromBase64String(data);
byte[] decBytes = DecryptData(encBytes, password, PaddingMode.ISO10126);
return Encoding.UTF8.GetString(decBytes);
}
public static byte[] EncryptData(byte[] data, string password, PaddingMode paddingMode)
{
if ( data == null || data.Length == 0 )
throw new ArgumentNullException("data");
if ( password == null )
throw new ArgumentNullException("password");
PasswordDeriveBytes pdb = new PasswordDeriveBytes(password, Encoding.UTF8.GetBytes("Salt"));
RijndaelManaged rm = new RijndaelManaged();
rm.Padding = paddingMode;
ICryptoTransform encryptor = rm.CreateEncryptor(pdb.GetBytes(16), pdb.GetBytes(16));
using ( MemoryStream msEncrypt = new MemoryStream() )
using ( CryptoStream encStream = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write) )
{
encStream.Write(data, 0, data.Length);
encStream.FlushFinalBlock();
return msEncrypt.ToArray();
}
}
public static byte[] DecryptData(byte[] data, string password, PaddingMode paddingMode)
{
if ( data == null || data.Length == 0 )
throw new ArgumentNullException("data");
if ( password == null )
throw new ArgumentNullException("password");
PasswordDeriveBytes pdb = new PasswordDeriveBytes(password, Encoding.UTF8.GetBytes("Salt"));
RijndaelManaged rm = new RijndaelManaged();
rm.Padding = paddingMode;
ICryptoTransform decryptor = rm.CreateDecryptor(pdb.GetBytes(16), pdb.GetBytes(16));
using ( MemoryStream msDecrypt = new MemoryStream(data) )
using ( CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read) )
{
// Decrypted bytes will always be less then encrypted bytes, so len of encrypted data will be big enouph for buffer.
byte[] fromEncrypt = new byte[data.Length];
// Read as many bytes as possible.
int read = csDecrypt.Read(fromEncrypt, 0, fromEncrypt.Length);
if ( read < fromEncrypt.Length )
{
// Return a byte array of proper size.
byte[] clearBytes = new byte[read];
Buffer.BlockCopy(fromEncrypt, 0, clearBytes, 0, read);
return clearBytes;
}
return fromEncrypt;
}
}
-- William Stacey [MVP]
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