/// <summary>
/// Decrypts the filename and initializes <see cref="Name"/> field value.
/// </summary>
/// <param name="file">Encrpted file in raw form.</param>
/// <param name="userId">Unique identifier of the logged-in user.</param>
/// <param name="userPrivateKey">Users private RSA key.</param>
private void DecryptName(byte[] file, int userId, RSAParameters userPrivateKey)
{
var offset = 44; // we are skipping StandardInformation header
var securityDescriptorHeader = new SecurityDescriptor();
securityDescriptorHeader.ParseSecurityDescriptor(file, ref offset);
OwnerId = securityDescriptorHeader.OwnerId;
try
{
var fileKey = securityDescriptorHeader.GetKey(userId, userPrivateKey); // if user isn't authorised to access the file, exception will be thrown
Name = Encoding.ASCII.GetString(new AesAlgorithm(fileKey, securityDescriptorHeader.IV, "OFB").Decrypt(Convert.FromBase64String(EncryptedName.Split('.')[0].Replace('$', '/'))));
}
// When reading files in Shared folder, users who don't have approved access will be able to see files in folder but won't be able to read them or see their real names.
catch (Exception)
{
//Name = EncryptedName;
}
}
