(Android™) SFTP Set Allowed Algorithms

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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.

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// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

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

    boolean success;
    CkSFtp sftp = new CkSFtp();

    CkJsonObject json = new 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.
    // -------------------------------------------------------------------------------------------------------------------------------------------
    String allowed_kex = "curve25519-sha256@libssh.org,ecdh-sha2-nistp256";
    String allowed_hostKey = "ssh-ed25519,ecdsa-sha2-nistp256";
    String allowed_cipher = "chacha20-poly1305@openssh.com,aes256-ctr";
    String allowed_mac = "hmac-sha2-256,hmac-sha2-512";

    json.UpdateString("kex",allowed_kex);
    json.UpdateString("hostKey",allowed_hostKey);
    json.UpdateString("cipher",allowed_cipher);
    json.UpdateString("mac",allowed_mac);
    sftp.SetAllowedAlgorithms(json);

    int port = 22;
    success = sftp.Connect("example.com",port);
    if (success != true) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    Log.i(TAG, "Connected.");

    // ....
    // ....

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}