com.ibm.mobilefirstplatform.clientsdk.android.security.mca.internal.certificate.DefaultJSONSigner.java Source code

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Here is the source code for com.ibm.mobilefirstplatform.clientsdk.android.security.mca.internal.certificate.DefaultJSONSigner.java

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/*
 *  Copyright 2015 IBM Corp.
 *  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.
 */

package com.ibm.mobilefirstplatform.clientsdk.android.security.mca.internal.certificate;

import android.util.Base64;

import org.json.JSONObject;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.Signature;
import java.security.SignatureException;
import java.security.interfaces.RSAPublicKey;

/**
 * Default implementation of the json payload signer
 * Created by cirilla on 8/3/15.
 */
public class DefaultJSONSigner implements JSONSigner {

    private static final String ALG = "alg";

    @Override
    public String sign(KeyPair keyPair, JSONObject json) throws Exception {

        if (keyPair == null || json == null) {
            throw new IllegalArgumentException("parameter cannot be null");
        }

        RSAPublicKey publicKey = ((RSAPublicKey) keyPair.getPublic());
        PrivateKey privateKey = keyPair.getPrivate();

        // create CSR Header (based on public key)
        JSONObject jwsHeaderJson = new JSONObject();
        jwsHeaderJson.put(ALG, "RS256");

        JSONObject publicKeyDataJson = new JSONObject();
        publicKeyDataJson.put(ALG, "RSA");

        String mod = encodeUrlSafe(publicKey.getModulus().toByteArray());
        publicKeyDataJson.put("mod", mod);

        String exp = encodeUrlSafe(publicKey.getPublicExponent().toByteArray());
        publicKeyDataJson.put("exp", exp);

        jwsHeaderJson.put("jpk", publicKeyDataJson);

        String jwsHeader = jwsHeaderJson.toString();
        String payload = json.toString();

        // concatenate JWS Header and payload.
        String csrHeaderAndPayload = encodeUrlSafe(jwsHeader.getBytes()) + "." + encodeUrlSafe(payload.getBytes());

        // create CSR Signature
        String jwsSignature = encodeUrlSafe(signCsrData(csrHeaderAndPayload, privateKey));

        // Concatenate them all, and return the result.
        return csrHeaderAndPayload + "." + jwsSignature;
    }

    private byte[] signCsrData(String csrJSONData, PrivateKey privateKey)
            throws NoSuchAlgorithmException, InvalidKeyException, SignatureException {
        Signature signature = Signature.getInstance("SHA256withRSA");
        signature.initSign(privateKey);
        signature.update(csrJSONData.getBytes());
        return signature.sign();
    }

    private String encodeUrlSafe(byte[] data) throws UnsupportedEncodingException {
        return new String(Base64.encode(data, Base64.URL_SAFE | Base64.NO_WRAP), "UTF-8");
    }
}