Android™

Convert a PuTTY Private Key (.ppk) to OpenSSH (.pem)

Demonstrates converting a PuTTY format private key to OpenSSH format. The .ppk is imported with FromPuttyPrivateKey and re-exported with ToOpenSshPrivateKey, both unencrypted and encrypted.

Note: The file paths are relative to the application's current working directory. Supply the paths to your own files.

Background: PuTTY and OpenSSH store the same underlying key material in different container formats, so converting between them is a re-encoding rather than a new key — the corresponding public key, and therefore the server-side authorized_keys entry, is unchanged. This matters when moving between Windows tooling built around PuTTY and Unix tooling that expects PEM. Note that the Password property serves double duty: it decrypts the key on import and encrypts it on export, so set it appropriately for each step.

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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 converting a PuTTY format private key (.ppk) to OpenSSH (.pem) format.

    CkSshKey key = new CkSshKey();

    //  Set the password before importing an encrypted PuTTY key.  If the key is not encrypted it
    //  makes no difference whether Password is set.  This should come from a secure source rather
    //  than being hard-coded.
    key.put_Password("myKeyPassword");

    //  LoadText is a convenience method that reads any text file into a string.  It does not itself
    //  load the key.
    String keyStr = key.loadText("qa_data/putty_private_key.ppk");
    if (key.get_LastMethodSuccess() == false) {
        Log.i(TAG, key.lastErrorText());
        return;
        }

    success = key.FromPuttyPrivateKey(keyStr);
    if (success == false) {
        Log.i(TAG, key.lastErrorText());
        return;
        }

    //  Export to an unencrypted OpenSSH key.
    boolean bEncrypt = false;
    String unencryptedKeyStr = key.toOpenSshPrivateKey(bEncrypt);
    if (key.get_LastMethodSuccess() == false) {
        Log.i(TAG, key.lastErrorText());
        return;
        }

    success = key.SaveText(unencryptedKeyStr,"qa_output/unencrypted_openssh.pem");
    if (success == false) {
        Log.i(TAG, key.lastErrorText());
        return;
        }

    //  Export to an encrypted OpenSSH key.  The Password property supplies the passphrase used to
    //  encrypt the output.
    bEncrypt = true;
    key.put_Password("myExportPassword");
    String encryptedKeyStr = key.toOpenSshPrivateKey(bEncrypt);
    if (key.get_LastMethodSuccess() == false) {
        Log.i(TAG, key.lastErrorText());
        return;
        }

    success = key.SaveText(encryptedKeyStr,"qa_output/encrypted_openssh.pem");
    if (success == false) {
        Log.i(TAG, key.lastErrorText());
        return;
        }

    Log.i(TAG, "Done!");

  }

  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."
  }
}