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(Android™) RSA Sign with PKCS8 Encrypted KeyDemonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it). Note: This example requires Chilkat v11.0.0 or greater.
// 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; // This example assumes the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. CkPrivateKey privKey = new CkPrivateKey(); // Load the private key from an RSA PEM file: success = privKey.LoadAnyFormatFile("raul_privateKey.key","a0123456789"); if (success == false) { Log.i(TAG, privKey.lastErrorText()); return; } CkRsa rsa = new CkRsa(); // Import the private key into the RSA component: success = rsa.UsePrivateKey(privKey); if (success == false) { Log.i(TAG, rsa.lastErrorText()); return; } // This example will sign a string, and receive the signature // in a hex-encoded string. Therefore, set the encoding mode // to "hex": rsa.put_EncodingMode("hex"); String strData = "This is the string to be signed."; // Sign the string using the sha256 hash algorithm. // Other valid choices are sha1, sha384, sha512 and others. String hexSig = rsa.signStringENC(strData,"sha256"); if (rsa.get_LastMethodSuccess() == false) { Log.i(TAG, rsa.lastErrorText()); return; } Log.i(TAG, hexSig); // Now verify with the public key. // This example shows how to use the public key from // a digital certificate (.cer file) CkCert cert = new CkCert(); success = cert.LoadFromFile("raul_publicKey.cer"); if (success == false) { Log.i(TAG, cert.lastErrorText()); return; } CkPublicKey pubKey = new CkPublicKey(); cert.GetPublicKey(pubKey); CkRsa rsa2 = new CkRsa(); success = rsa2.UsePublicKey(pubKey); if (success == false) { Log.i(TAG, rsa2.lastErrorText()); return; } // Verify the signature against the original data: rsa2.put_EncodingMode("hex"); success = rsa2.VerifyStringENC(strData,"sha256",hexSig); if (success == false) { Log.i(TAG, rsa2.lastErrorText()); return; } Log.i(TAG, "Signature verified!"); // Verify with incorrect data: success = rsa2.VerifyStringENC("something else","sha256",hexSig); if (success != true) { Log.i(TAG, "Signature not verified! (which was expected in this case)"); } else { Log.i(TAG, "Hmmm... that's not right..."); } } 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." } } |
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