Android™

Get the SFTP Server Host Key Fingerprint

Demonstrates the Chilkat SFtp.GetHostKeyFP method, which returns the connected server's host-key fingerprint. The first argument is the hash algorithm (for example SHA256 or MD5), the second controls whether the key type is included, and the third controls whether the hash name is included.

Background: The host-key fingerprint identifies the server. Comparing it against a known-good value is how a client implements host-key pinning — detecting a man-in-the-middle attempt or a changed server key before trusting the connection with credentials or files. SHA256 is the modern default; MD5 fingerprints still appear in older tooling but are weaker.

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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);

    boolean success = false;

    //  Demonstrates the SFtp.GetHostKeyFP method, which returns the server's host-key fingerprint.
    //  The 1st argument is the hash algorithm, the 2nd controls whether the key type is included, and
    //  the 3rd controls whether the hash name is included.

    CkSFtp sftp = new CkSFtp();

    //  Step 1: Connect the SSH transport.  Port 22 is the usual port.
    int port = 22;
    success = sftp.Connect("sftp.example.com",port);
    if (success == false) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    //  Get the SHA256 fingerprint, including the key type and hash name.
    boolean includeKeyType = true;
    boolean includeHashName = true;
    String fingerprint = sftp.getHostKeyFP("SHA256",includeKeyType,includeHashName);
    if (sftp.get_LastMethodSuccess() == false) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    Log.i(TAG, "Host key fingerprint: " + fingerprint);

    sftp.Disconnect();

  }

  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."
  }
}