package com.cedarsoftware.util;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.StandardCharsets;
import java.security.Key;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
/**
* Useful encryption utilities that simplify tasks like getting an
* encrypted String return value (or MD5 hash String) for String or
* Stream input.
* @author John DeRegnaucourt (john@cedarsoftware.com)
* <br>
* Copyright (c) Cedar Software LLC
* <br><br>
* 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
* <br><br>
* http://www.apache.org/licenses/LICENSE-2.0
* <br><br>
* 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.
*/
public class EncryptionUtilities
{
private EncryptionUtilities()
{
}
/**
* Super-fast MD5 calculation from entire file. Uses FileChannel and
* direct ByteBuffer (internal JVM memory).
* @param file File that from which to compute the MD5
* @return String MD5 value.
*/
public static String fastMD5(File file)
{
try (FileInputStream in = new FileInputStream(file))
{
return calculateMD5Hash(in.getChannel());
}
catch (IOException e)
{
return null;
}
}
public static String calculateMD5Hash(FileChannel ch) throws IOException
{
ByteBuffer bb = ByteBuffer.allocateDirect(65536);
MessageDigest d = getMD5Digest();
int nRead;
while ((nRead = ch.read(bb)) != -1)
{
if (nRead == 0)
{
continue;
}
bb.position(0);
bb.limit(nRead);
d.update(bb);
bb.clear();
}
return ByteUtilities.encode(d.digest());
}
/**
* Calculate an MD5 Hash String from the passed in byte[].
* @param bytes byte[] for which to obtain the MD5 hash.
* @return String of hex digits representing MD5 hash.
*/
public static String calculateMD5Hash(byte[] bytes)
{
return calculateHash(getMD5Digest(), bytes);
}
public static MessageDigest getDigest(String digest)
{
try
{
return MessageDigest.getInstance(digest);
}
catch (NoSuchAlgorithmException e)
{
throw new IllegalArgumentException(String.format("The requested MessageDigest (%s) does not exist", digest), e);
}
}
public static MessageDigest getMD5Digest()
{
return getDigest("MD5");
}
/**
* Calculate an MD5 Hash String from the passed in byte[].
*/
public static String calculateSHA1Hash(byte[] bytes)
{
return calculateHash(getSHA1Digest(), bytes);
}
public static MessageDigest getSHA1Digest()
{
return getDigest("SHA-1");
}
/**
* Calculate an SHA-256 Hash String from the passed in byte[].
*/
public static String calculateSHA256Hash(byte[] bytes)
{
return calculateHash(getSHA256Digest(), bytes);
}
public static MessageDigest getSHA256Digest()
{
return getDigest("SHA-256");
}
/**
* Calculate an SHA-512 Hash String from the passed in byte[].
*/
public static String calculateSHA512Hash(byte[] bytes)
{
return calculateHash(getSHA512Digest(), bytes);
}
public static MessageDigest getSHA512Digest()
{
return getDigest("SHA-512");
}
public static byte[] createCipherBytes(String key, int bitsNeeded)
{
String word = calculateMD5Hash(key.getBytes(StandardCharsets.UTF_8));
return word.substring(0, bitsNeeded / 8).getBytes(StandardCharsets.UTF_8);
}
public static Cipher createAesEncryptionCipher(String key) throws Exception
{
return createAesCipher(key, Cipher.ENCRYPT_MODE);
}
public static Cipher createAesDecryptionCipher(String key) throws Exception
{
return createAesCipher(key, Cipher.DECRYPT_MODE);
}
public static Cipher createAesCipher(String key, int mode) throws Exception
{
Key sKey = new SecretKeySpec(createCipherBytes(key, 128), "AES");
return createAesCipher(sKey, mode);
}
/**
* Creates a Cipher from the passed in key, using the passed in mode.
* @param key SecretKeySpec
* @param mode Cipher.ENCRYPT_MODE or Cipher.DECRYPT_MODE
* @return Cipher instance created with the passed in key and mode.
*/
public static Cipher createAesCipher(Key key, int mode) throws Exception
{
// Use password key as seed for IV (must be 16 bytes)
MessageDigest d = getMD5Digest();
d.update(key.getEncoded());
byte[] iv = d.digest();
AlgorithmParameterSpec paramSpec = new IvParameterSpec(iv);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); // CBC faster than CFB8/NoPadding (but file length changes)
cipher.init(mode, key, paramSpec);
return cipher;
}
/**
* Get hex String of content String encrypted.
*/
public static String encrypt(String key, String content)
{
try
{
return ByteUtilities.encode(createAesEncryptionCipher(key).doFinal(content.getBytes(StandardCharsets.UTF_8)));
}
catch (Exception e)
{
throw new IllegalStateException("Error occurred encrypting data", e);
}
}
public static String encryptBytes(String key, byte[] content)
{
try
{
return ByteUtilities.encode(createAesEncryptionCipher(key).doFinal(content));
}
catch (Exception e)
{
throw new IllegalStateException("Error occurred encrypting data", e);
}
}
/**
* Get unencrypted String from encrypted hex String
*/
public static String decrypt(String key, String hexStr)
{
try
{
return new String(createAesDecryptionCipher(key).doFinal(ByteUtilities.decode(hexStr)));
}
catch (Exception e)
{
throw new IllegalStateException("Error occurred decrypting data", e);
}
}
/**
* Get unencrypted byte[] from encrypted hex String
*/
public static byte[] decryptBytes(String key, String hexStr)
{
try
{
return createAesDecryptionCipher(key).doFinal(ByteUtilities.decode(hexStr));
}
catch (Exception e)
{
throw new IllegalStateException("Error occurred decrypting data", e);
}
}
/**
* Calculate an SHA-256 Hash String from the passed in byte[].
*/
public static String calculateHash(MessageDigest d, byte[] bytes)
{
if (bytes == null)
{
return null;
}
d.update(bytes);
return ByteUtilities.encode(d.digest());
}
}