Java tutorial
//package com.java2s; /* * * Copyright (C) 2015 Orange Labs * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */ import java.math.BigInteger; import java.security.KeyFactory; import java.security.PublicKey; import java.security.spec.RSAPublicKeySpec; import org.json.JSONObject; import android.util.Base64; public class Main { public static PublicKey pubKeyFromJwk(String jwkp) { PublicKey pubKey = null; try { JSONObject jk = new JSONObject(jwkp).getJSONArray("keys").getJSONObject(0); BigInteger n = new BigInteger(1, decodeB64(jk.getString("n"))); BigInteger e = new BigInteger(1, decodeB64(jk.getString("e"))); RSAPublicKeySpec pubRsaSpec = new RSAPublicKeySpec(n, e); KeyFactory keyfact = KeyFactory.getInstance("RSA", "SC"); pubKey = keyfact.generatePublic(pubRsaSpec); } catch (Exception e) { e.printStackTrace(); } return pubKey; } static byte[] decodeB64(String s64) { return Base64.decode(s64, Base64.URL_SAFE); } }