/// <summary>
/// Decrypts an encrypted object to get the original text.
/// </summary>
/// <param name="cryptoItem">The encrypted object.</param>
/// <returns>The decrypted text.</returns>
public string Decrypt(ICryptoItem cryptoItem)
{
Ensure.Parameter.IsNotNull(cryptoItem, nameof(cryptoItem));
string decryptedText;
using (MemoryStream ms = new MemoryStream(cryptoItem.Value))
{
using (CryptoStream cs = GetCryptoStream(ms, CryptoStreamMode.Read, cryptoItem))
{
using (StreamReader sr = new StreamReader(cs))
{
decryptedText = sr.ReadToEnd();
}
}
}
return(decryptedText);
}
/// <summary>
/// Gets a crypto stream.
/// </summary>
/// <param name="memoryStream">The stream to encrypt.</param>
/// <param name="mode">If the crypto stream is for reading or writing.</param>
/// <param name="cryptoItem">The encrypted item to read.</param>
/// <returns>The crypto stream.</returns>
private CryptoStream GetCryptoStream(MemoryStream memoryStream, CryptoStreamMode mode, ICryptoItem cryptoItem = null)
{
var cryptoProvider = new AesCryptoServiceProvider();
byte[] key = cryptoItem?.Key ?? _cryptoServiceProvider.Key;
byte[] iv = cryptoItem?.InitializationVector ?? _cryptoServiceProvider.IV;
var transform = mode == CryptoStreamMode.Read
? cryptoProvider.CreateDecryptor(key, iv)
: cryptoProvider.CreateEncryptor(key, iv);
return(new CryptoStream(memoryStream, transform, mode));
}
