(Android™) secp256k1 Key Generation and Keccak-256

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Note: This example requires Chilkat v11.0.0 or greater.

Chilkat Android™ Downloads Android™ Java Libraries Android C/C++ Libraries

// 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.

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

    CkEcc ecc = new CkEcc();

    // Generate a random ECDSA private key on the secp256k1 curve.
    CkPrivateKey privKey = ecc.GenEccKey("secp256k1",fortuna);
    if (ecc.get_LastMethodSuccess() != true) {
        Log.i(TAG, ecc.lastErrorText());
        return;
        }

    Log.i(TAG, "Successfully generated a sec256k1 key.");

    // Show how to compute the Keccak-256 hash in a few ways.
    CkStringBuilder sb = new CkStringBuilder();
    sb.Append("hello");

    Log.i(TAG, "keccak-256: " + sb.getHash("keccak-256","hex_lower","utf-8"));

    // Output:
    // keccak-256: 1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8

    // To keccak-256 hash binary data
    CkBinData bd = new CkBinData();
    bd.AppendEncoded("00010203040506","hex");

    Log.i(TAG, "keccak-256: " + bd.getHash("keccak-256","hex_lower"));

    // Output:
    // keccak-256: 801560412425120fa609be232d6fa71c7f64f42aee7977267687dcc0a2f5aa63

  }

  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."
  }
}