it.smartcommunitylab.aac.oauth.AACOAuth2Utils.java Source code

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Here is the source code for it.smartcommunitylab.aac.oauth.AACOAuth2Utils.java

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/*******************************************************************************
 * Copyright 2015 Fondazione Bruno Kessler
 * 
 *    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 it.smartcommunitylab.aac.oauth;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.apache.commons.codec.binary.Base64;
import org.springframework.security.crypto.codec.Utf8;

/**
 * @author raman
 *
 */
public class AACOAuth2Utils {
    public static final String CODE_CHALLENGE = "code_challenge";
    public static final Object CODE_VERIFIER = "code_verifier";
    public static final Object CODE_CHALLENGE_METHOD = "code_challenge_method";

    /**
     * Generates the code challenge from a given code verifier and code challenge method.
     * @param codeVerifier
     * @param codeChallengeMethod allowed values are only <code>plain</code> and <code>S256</code>
     * @return
     */
    public static String getCodeChallenge(String codeVerifier, String codeChallengeMethod) {
        if (codeChallengeMethod.equals("plain")) {
            return codeVerifier;
        } else if (codeChallengeMethod.equalsIgnoreCase("S256")) {
            return getS256CodeChallenge(codeVerifier);
        } else {
            throw new IllegalArgumentException(codeChallengeMethod + " is not a supported code challenge method.");
        }
    }

    private static String getS256CodeChallenge(String codeVerifier) {
        MessageDigest md;
        try {
            md = MessageDigest.getInstance("SHA-256");
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalArgumentException("No such algorithm [SHA-256]");
        }
        byte[] sha256 = md.digest(Utf8.encode(codeVerifier));
        String codeChallenge = Base64.encodeBase64URLSafeString(sha256);
        return codeChallenge;
    }

}