com.google.dosidos.util.EncryptionUtil.java Source code

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Here is the source code for com.google.dosidos.util.EncryptionUtil.java

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// Copyright 2016 Google Inc.
//
// 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.google.dosidos.util;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;
import javax.xml.bind.DatatypeConverter;

import com.google.common.io.BaseEncoding;

/**
 * Uses a key to encrypt/decrypt a cookie value.
 */
public class EncryptionUtil {

    public static String encrypt(String plainText, String key) {
        try {
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.ENCRYPT_MODE, getAesKey(key));
            byte[] salt = new byte[8];
            SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
            random.nextBytes(salt);
            cipher.update(salt);
            byte[] encrypted = cipher.doFinal(plainText.getBytes("ISO-8859-1"));
            return BaseEncoding.base64Url().encode(encrypted);
        } catch (InvalidKeyException e) {
            throw new RuntimeException(e);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        } catch (NoSuchPaddingException e) {
            throw new RuntimeException(e);
        } catch (IllegalBlockSizeException e) {
            throw new RuntimeException(e);
        } catch (BadPaddingException e) {
            throw new RuntimeException(e);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }
    }

    public static String decrypt(String encryptedText, String key) {
        try {
            byte[] encrypted = BaseEncoding.base64Url().decode(encryptedText);
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.DECRYPT_MODE, getAesKey(key));
            byte[] plain = cipher.doFinal(encrypted);
            if (plain == null || plain.length <= 8) {
                throw new RuntimeException("wrong encrypted text.");
            }
            byte[] data = new byte[plain.length - 8];
            System.arraycopy(plain, 8, data, 0, data.length);
            return new String(data, "ISO-8859-1");
        } catch (InvalidKeyException e) {
            throw new RuntimeException(e);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        } catch (NoSuchPaddingException e) {
            throw new RuntimeException(e);
        } catch (IllegalBlockSizeException e) {
            throw new RuntimeException(e);
        } catch (BadPaddingException e) {
            throw new RuntimeException(e);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }
    }

    private static SecretKeySpec getAesKey(String key) {
        final byte[] symKeyData = DatatypeConverter.parseHexBinary(key);
        return new SecretKeySpec(symKeyData, "AES");
    }
}