Android™

Generate ECDSA Key and Get Details as XML

See more ECC Examples

Demonstrates how to generate an ECDSA key and gets the parts as XML. Android™

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

    CkEcc ecc = new CkEcc();

    // Generate a random ECC private key on the secp256k1 curve.
    // Chilkat also supports other curves, such as secp384r1, secp521r1, and secp256r1.

    // Create a Fortuna PRNG and seed it with system entropy.
    // This will be our source of random data for generating the ECC private key.
    CkPrng fortuna = new CkPrng();
    String entropy = fortuna.getEntropy(32,"base64");
    success = fortuna.AddEntropy(entropy,"base64");

    CkPrivateKey privKey = new CkPrivateKey();
    success = ecc.GenKey("secp256k1",fortuna,privKey);
    if (success == false) {
        Log.i(TAG, ecc.lastErrorText());
        return;
        }

    // An EC private key has this ASN.1
    // ECPrivateKey ::= SEQUENCE {
    //     version        INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
    //     privateKey     OCTET STRING,
    //     parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
    //     publicKey  [1] BIT STRING OPTIONAL (This is the ANSI X9.63 public key format.)

    CkAsn asn = new CkAsn();
    success = asn.LoadEncoded(privKey.getPkcs1ENC("base64"),"base64");
    if (success != true) {
        Log.i(TAG, asn.lastErrorText());
        return;
        }

    CkXml xml = new CkXml();
    xml.LoadXml(asn.asnToXml());

    Log.i(TAG, xml.getXml());

    // The XML looks like this:
    // <?xml version="1.0" encoding="utf-8" ?>
    // <sequence>
    //     <int>01</int>
    //     <octets>JgJvBG+3wletkJab8iXAkpz0O8/AgWZSpkYVcB7SpnU=</octets>
    //     <contextSpecific tag="0" constructed="1">
    //         <oid>1.3.132.0.10</oid>
    //     </contextSpecific>
    // </sequence>

    // The 32-byte private key is in the octets..
    // Get it as hex.
    CkCrypt2 crypt = new CkCrypt2();
    String privKeyHex = crypt.reEncode(xml.getChildContent("octets"),"base64","hex");

    Log.i(TAG, "EC private key as hex = " + privKeyHex);

  }

  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."
  }
}