Dart

SFTP Set Allowed Algorithms

See more SFTP Examples

Demonstrates how to explicitly set the algorithms allowed in the SSH connection protocol for SFTP.

Note: This example requires Chilkat v9.5.0.99 or greater.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final sftp = CkSFtp();

  final json = CkJsonObject();

  // Here are the algorithms supported by Chilkat at the time this example was written (14-June-2024)

  // ---------------------------
  // SSH Key-Exchange Algorithms
  // ---------------------------
  // curve25519-sha256
  // curve25519-sha256@libssh.org
  // ecdh-sha2-nistp256
  // ecdh-sha2-nistp384
  // ecdh-sha2-nistp521
  // diffie-hellman-group14-sha256
  // diffie-hellman-group16-sha512
  // diffie-hellman-group18-sha512
  // diffie-hellman-group-exchange-sha256
  // diffie-hellman-group1-sha1
  // diffie-hellman-group14-sha1
  // diffie-hellman-group-exchange-sha1

  // ---------------------------
  // SSH Host Key Algorithms
  // ---------------------------
  // ssh-ed25519
  // ecdsa-sha2-nistp256
  // ecdsa-sha2-nistp384
  // ecdsa-sha2-nistp521
  // rsa-sha2-256
  // rsa-sha2-512
  // ssh-rsa
  // ssh-dss

  // ---------------------------
  // SSH Cipher Algorithms
  // ---------------------------
  // chacha20-poly1305@openssh.com
  // aes128-ctr
  // aes256-ctr
  // aes192-ctr
  // aes128-cbc
  // aes256-cbc
  // aes192-cbc
  // aes128-gcm@openssh.com
  // aes256-gcm@openssh.com
  // twofish256-cbc
  // twofish128-cbc
  // blowfish-cbc

  // ---------------------------
  // SSH MAC Algorithms
  // ---------------------------
  // hmac-sha2-256
  // hmac-sha2-512
  // hmac-sha2-256-etm@openssh.com
  // hmac-sha2-512-etm@openssh.com
  // hmac-sha1-etm@openssh.com
  // hmac-sha1
  // hmac-ripemd160
  // hmac-sha1-96
  // hmac-md5

  // Specify the allowed key-exchange, host-key, cipher (i.e. encryption), and mac (i.e. hash) algorithms allowed, in the order of preference.
  // -------------------------------------------------------------------------------------------------------------------------------------------
  // Note: You typically should NOT explicitly set allowed algorithms.
  // By default, Chilkat orders algorithms according to best practices, and pays attention to vulnerabilities such as the "Terrapin Attack".
  // Hard-coding algorthims can make your application brittle and prone to breaking over a long period of time,
  // if a server (at some point in the future) changes its allowed algorithms, or if you connect to a different server,
  // such that the client (Chilkat) and server cannot find a set of mutually agreed-upon algorithms.
  // -------------------------------------------------------------------------------------------------------------------------------------------
  final allowedKex = 'curve25519-sha256@libssh.org,ecdh-sha2-nistp256';
  final allowedHostKey = 'ssh-ed25519,ecdsa-sha2-nistp256';
  final allowedCipher = 'chacha20-poly1305@openssh.com,aes256-ctr';
  final allowedMac = 'hmac-sha2-256,hmac-sha2-512';

  json.updateString('kex', allowedKex);
  json.updateString('hostKey', allowedHostKey);
  json.updateString('cipher', allowedCipher);
  json.updateString('mac', allowedMac);
  sftp.setAllowedAlgorithms(json);

  final port = 22;
  try {
    sftp.connect('example.com', port);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Connected.');

  // ....
  // ....
}