com.twosigma.jupyter.security.HashedMessageAuthenticationCode.java Source code

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Here is the source code for com.twosigma.jupyter.security.HashedMessageAuthenticationCode.java

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/*
 *  Copyright 2017 TWO SIGMA OPEN SOURCE, LLC
 *
 *  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.twosigma.jupyter.security;

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.List;
import java.util.stream.Collectors;

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

import org.apache.commons.codec.binary.Hex;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static com.google.common.base.Preconditions.checkNotNull;

public class HashedMessageAuthenticationCode {

    private static final String TYPE = "HmacSHA256";
    private static final String INVALID_HMAC_EXCEPTION = "Invalid key exception while converting to " + TYPE;
    private static Logger logger = LoggerFactory.getLogger(HashedMessageAuthenticationCode.class);

    private SecretKeySpec spec;

    public HashedMessageAuthenticationCode(String key) {
        checkNotNull(key, "No key specified");
        logger.info("Using signing hmac: {}", key);
        spec = new SecretKeySpec(key.getBytes(), TYPE);
    }

    public String sign(List<String> msg) {
        List<byte[]> collect = msg.stream().map(String::getBytes).collect(Collectors.toList());
        return signBytes(collect);
    }

    public String signBytes(List<byte[]> msg) {
        try {
            final Mac mac = Mac.getInstance(TYPE);
            mac.init(spec);
            msg.forEach(it -> mac.update(it));
            byte[] digest = mac.doFinal();
            return toHex(digest);
        } catch (InvalidKeyException e) {
            throw new RuntimeException(INVALID_HMAC_EXCEPTION, e);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }

    public String toHex(byte[] buffer) {
        return Hex.encodeHexString(buffer);
    }

}