private static string Encrypt004(string content, byte[] key, string assocData)
{
var nonce = RandomSeed(24);
var authenticated_data = Convert.ToBase64String(Encoding.UTF8.GetBytes(assocData));
var ciphertext = ANCrypt.XChaCha20Encrypt(Encoding.UTF8.GetBytes(content), EncodingConverter.StringToByteArrayCaseInsensitive(nonce), key, Encoding.UTF8.GetBytes(authenticated_data));
return(string.Join(":", "004", nonce, Convert.ToBase64String(ciphertext), authenticated_data));
}
public static (byte[] mk, byte[] sp, string reqpw) CreateAuthData004(StandardNoteAPI.APIResultAuthParams apiparams, string mail, string uip)
{
var salt = StandardNoteCrypt.SHA256Bytes(string.Join(":", apiparams.identifier, apiparams.pw_nonce)).Take(128 / 8).ToArray();
var derivedKey = ANCrypt.Argon2(Encoding.UTF8.GetBytes(uip), salt, 5, 64 * 1024, 64);
var masterKey = derivedKey.Skip(00).Take(32).ToArray();
var serverPassword = derivedKey.Skip(32).Take(32).ToArray();
var requestPassword = EncodingConverter.ByteToHexBitFiddleLowercase(serverPassword);
return(masterKey, serverPassword, requestPassword);
}
private static string Decrypt004(string encContent, byte[] key)
{
var split = encContent.Split(':');
var version = split[0];
var nonce = EncodingConverter.StringToByteArrayCaseInsensitive(split[1]);
var ciphertext = Convert.FromBase64String(split[2]);
var authenticated_data = Encoding.UTF8.GetBytes(split[3]);
if (version != "004")
{
throw new StandardNoteAPIException($"Version must be 004 to decrypt 004 encrypted item (duh.)");
}
var plain = ANCrypt.XChaCha20Decrypt(ciphertext, nonce, key, authenticated_data);
return(Encoding.UTF8.GetString(plain));
}