io.pivotal.cla.security.GitHubSignature.java Source code

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Here is the source code for io.pivotal.cla.security.GitHubSignature.java

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/*
 * Copyright 2002-2016 the original author or authors.
 *
 * 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 io.pivotal.cla.security;

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

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.crypto.codec.Hex;
import org.springframework.stereotype.Component;

import io.pivotal.cla.data.AccessToken;
import io.pivotal.cla.data.repository.AccessTokenRepository;
import lombok.SneakyThrows;

/**
 * @author Rob Winch
 *
 */
@Component
public class GitHubSignature {
    static final String SIGNATURE_PREFIX = "sha1=";

    private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1";

    AccessTokenRepository accessTokens;

    @Autowired
    public GitHubSignature(AccessTokenRepository accessTokens) {
        super();
        this.accessTokens = accessTokens;
    }

    @SneakyThrows
    public boolean check(String gitHubSignature, String body) {
        if (gitHubSignature == null || !gitHubSignature.startsWith(SIGNATURE_PREFIX)) {
            return false;
        }
        AccessToken expectedToken = accessTokens.findOne(AccessToken.CLA_ACCESS_TOKEN_ID);
        if (expectedToken == null) {
            return false;
        }

        String providedHmac = gitHubSignature.substring(SIGNATURE_PREFIX.length());

        byte[] providedHmacBytes = Hex.decode(providedHmac);

        byte[] expectedBytes = sign(body, expectedToken.getToken());

        return MessageDigest.isEqual(providedHmacBytes, expectedBytes);
    }

    @SneakyThrows
    public String create(String body, String token) {
        return SIGNATURE_PREFIX + new String(Hex.encode(sign(body, token)));
    }

    private byte[] sign(String body, String token) throws NoSuchAlgorithmException, InvalidKeyException {
        SecretKeySpec signingKey = new SecretKeySpec(token.getBytes(), HMAC_SHA1_ALGORITHM);
        Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
        mac.init(signingKey);
        byte[] expectedBytes = mac.doFinal(body.getBytes());
        return expectedBytes;
    }
}