/// <summary>
/// Encode the data. The data is encrypted using the default encryption algorithm (AES-256),
/// then the AES key is encrypted using RSA and the RSA public key is appended.
/// </summary>
/// <param name="value">The data to encode</param>
/// <exception cref="ArgumentNullException">The argument 'value' is null.</exception>
/// <exception cref="ArgumentException">The argument 'value' contains zero bytes.</exception>
/// <exception cref="InvalidOperationException">The EncryptionKey is null.</exception>
/// <returns>Encoded data</returns>
public override byte[] Encode(byte[] value)
{
if (null == value)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("value");
}
if (0 == value.Length)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgument("value", SR.GetString(SR.ID6044));
}
RSA encryptionKey = EncryptionKey;
if (null == encryptionKey)
{
throw DiagnosticUtility.ThrowHelperInvalidOperation(SR.GetString(SR.ID6043));
}
byte[] rsaHash;
byte[] encryptedKeyAndIV;
byte[] encryptedData;
using (HashAlgorithm hash = CryptoHelper.CreateHashAlgorithm(_hashName))
{
rsaHash = hash.ComputeHash(Encoding.UTF8.GetBytes(encryptionKey.ToXmlString(false)));
}
using (SymmetricAlgorithm encryptionAlgorithm = CryptoHelper.NewDefaultEncryption())
{
encryptionAlgorithm.GenerateIV();
encryptionAlgorithm.GenerateKey();
using (ICryptoTransform encryptor = encryptionAlgorithm.CreateEncryptor())
{
encryptedData = encryptor.TransformFinalBlock(value, 0, value.Length);
}
RSACryptoServiceProvider provider = encryptionKey as RSACryptoServiceProvider;
if (provider == null)
{
throw DiagnosticUtility.ThrowHelperInvalidOperation(SR.GetString(SR.ID6041));
}
//
// Concatenate the Key and IV in an attempt to avoid two minimum block lengths in the cookie
//
byte[] keyAndIV = new byte[encryptionAlgorithm.Key.Length + encryptionAlgorithm.IV.Length];
Array.Copy(encryptionAlgorithm.Key, keyAndIV, encryptionAlgorithm.Key.Length);
Array.Copy(encryptionAlgorithm.IV, 0, keyAndIV, encryptionAlgorithm.Key.Length, encryptionAlgorithm.IV.Length);
encryptedKeyAndIV = CngLightup.OaepSha1Encrypt(encryptionKey, keyAndIV);
}
using (MemoryStream ms = new MemoryStream())
{
using (BinaryWriter bw = new BinaryWriter(ms))
{
bw.Write(rsaHash);
bw.Write(encryptedKeyAndIV.Length);
bw.Write(encryptedKeyAndIV);
bw.Write(encryptedData.Length);
bw.Write(encryptedData);
bw.Flush();
}
return(ms.ToArray());
}
}
