エリクソンの提案を読んで、他のいくつかの投稿とこの例からここで私が何ができるかを調べた後、推奨される変更でDougのコードを更新しようとしました。それをより良くするために自由に編集してください。
- 初期化ベクトルは修正されなくなりました
- 暗号化キーはエリクソンのコードを使用して導出されます
- SecureRandom（）を使用してsetupEncrypt（）で8バイトのソルトが生成されます
- 復号化キーは、暗号化ソルトとパスワードから生成されます
- 復号化暗号は、復号化キーと初期化ベクトルから生成されます
- org.apache.commons コーデック Hexルーチンの代わりにhex twiddlingを削除
いくつかの注記：これは128ビットの暗号化キーを使用します-明らかにJavaは256ビットの暗号化をそのままでは実行しません。256を実装するには、Javaインストールディレクトリに追加のファイルをインストールする必要があります。
また、私は暗号の人ではありません。注意してください。
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.AlgorithmParameters;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.InvalidParameterSpecException;
import java.security.spec.KeySpec;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.binary.Hex;
public class Crypto
{
String mPassword = null;
public final static int SALT_LEN = 8;
byte [] mInitVec = null;
byte [] mSalt = null;
Cipher mEcipher = null;
Cipher mDecipher = null;
private final int KEYLEN_BITS = 128; // see notes below where this is used.
private final int ITERATIONS = 65536;
private final int MAX_FILE_BUF = 1024;
/**
* create an object with just the passphrase from the user. Don't do anything else yet
* @param password
*/
public Crypto (String password)
{
mPassword = password;
}
/**
* return the generated salt for this object
* @return
*/
public byte [] getSalt ()
{
return (mSalt);
}
/**
* return the initialization vector created from setupEncryption
* @return
*/
public byte [] getInitVec ()
{
return (mInitVec);
}
/**
* debug/print messages
* @param msg
*/
private void Db (String msg)
{
System.out.println ("** Crypt ** " + msg);
}
/**
* this must be called after creating the initial Crypto object. It creates a salt of SALT_LEN bytes
* and generates the salt bytes using secureRandom(). The encryption secret key is created
* along with the initialization vectory. The member variable mEcipher is created to be used
* by the class later on when either creating a CipherOutputStream, or encrypting a buffer
* to be written to disk.
*
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
* @throws NoSuchPaddingException
* @throws InvalidParameterSpecException
* @throws IllegalBlockSizeException
* @throws BadPaddingException
* @throws UnsupportedEncodingException
* @throws InvalidKeyException
*/
public void setupEncrypt () throws NoSuchAlgorithmException,
InvalidKeySpecException,
NoSuchPaddingException,
InvalidParameterSpecException,
IllegalBlockSizeException,
BadPaddingException,
UnsupportedEncodingException,
InvalidKeyException
{
SecretKeyFactory factory = null;
SecretKey tmp = null;
// crate secureRandom salt and store as member var for later use
mSalt = new byte [SALT_LEN];
SecureRandom rnd = new SecureRandom ();
rnd.nextBytes (mSalt);
Db ("generated salt :" + Hex.encodeHexString (mSalt));
factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
/* Derive the key, given password and salt.
*
* in order to do 256 bit crypto, you have to muck with the files for Java's "unlimted security"
* The end user must also install them (not compiled in) so beware.
* see here: http://www.javamex.com/tutorials/cryptography/unrestricted_policy_files.shtml
*/
KeySpec spec = new PBEKeySpec (mPassword.toCharArray (), mSalt, ITERATIONS, KEYLEN_BITS);
tmp = factory.generateSecret (spec);
SecretKey secret = new SecretKeySpec (tmp.getEncoded(), "AES");
/* Create the Encryption cipher object and store as a member variable
*/
mEcipher = Cipher.getInstance ("AES/CBC/PKCS5Padding");
mEcipher.init (Cipher.ENCRYPT_MODE, secret);
AlgorithmParameters params = mEcipher.getParameters ();
// get the initialization vectory and store as member var
mInitVec = params.getParameterSpec (IvParameterSpec.class).getIV();
Db ("mInitVec is :" + Hex.encodeHexString (mInitVec));
}
/**
* If a file is being decrypted, we need to know the pasword, the salt and the initialization vector (iv).
* We have the password from initializing the class. pass the iv and salt here which is
* obtained when encrypting the file initially.
*
* @param initvec
* @param salt
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
* @throws NoSuchPaddingException
* @throws InvalidKeyException
* @throws InvalidAlgorithmParameterException
* @throws DecoderException
*/
public void setupDecrypt (String initvec, String salt) throws NoSuchAlgorithmException,
InvalidKeySpecException,
NoSuchPaddingException,
InvalidKeyException,
InvalidAlgorithmParameterException,
DecoderException
{
SecretKeyFactory factory = null;
SecretKey tmp = null;
SecretKey secret = null;
// since we pass it as a string of input, convert to a actual byte buffer here
mSalt = Hex.decodeHex (salt.toCharArray ());
Db ("got salt " + Hex.encodeHexString (mSalt));
// get initialization vector from passed string
mInitVec = Hex.decodeHex (initvec.toCharArray ());
Db ("got initvector :" + Hex.encodeHexString (mInitVec));
/* Derive the key, given password and salt. */
// in order to do 256 bit crypto, you have to muck with the files for Java's "unlimted security"
// The end user must also install them (not compiled in) so beware.
// see here:
// http://www.javamex.com/tutorials/cryptography/unrestricted_policy_files.shtml
factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(mPassword.toCharArray (), mSalt, ITERATIONS, KEYLEN_BITS);
tmp = factory.generateSecret(spec);
secret = new SecretKeySpec(tmp.getEncoded(), "AES");
/* Decrypt the message, given derived key and initialization vector. */
mDecipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
mDecipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(mInitVec));
}
/**
* This is where we write out the actual encrypted data to disk using the Cipher created in setupEncrypt().
* Pass two file objects representing the actual input (cleartext) and output file to be encrypted.
*
* there may be a way to write a cleartext header to the encrypted file containing the salt, but I ran
* into uncertain problems with that.
*
* @param input - the cleartext file to be encrypted
* @param output - the encrypted data file
* @throws IOException
* @throws IllegalBlockSizeException
* @throws BadPaddingException
*/
public void WriteEncryptedFile (File input, File output) throws
IOException,
IllegalBlockSizeException,
BadPaddingException
{
FileInputStream fin;
FileOutputStream fout;
long totalread = 0;
int nread = 0;
byte [] inbuf = new byte [MAX_FILE_BUF];
fout = new FileOutputStream (output);
fin = new FileInputStream (input);
while ((nread = fin.read (inbuf)) > 0 )
{
Db ("read " + nread + " bytes");
totalread += nread;
// create a buffer to write with the exact number of bytes read. Otherwise a short read fills inbuf with 0x0
// and results in full blocks of MAX_FILE_BUF being written.
byte [] trimbuf = new byte [nread];
for (int i = 0; i < nread; i++)
trimbuf[i] = inbuf[i];
// encrypt the buffer using the cipher obtained previosly
byte [] tmp = mEcipher.update (trimbuf);
// I don't think this should happen, but just in case..
if (tmp != null)
fout.write (tmp);
}
// finalize the encryption since we've done it in blocks of MAX_FILE_BUF
byte [] finalbuf = mEcipher.doFinal ();
if (finalbuf != null)
fout.write (finalbuf);
fout.flush();
fin.close();
fout.close();
Db ("wrote " + totalread + " encrypted bytes");
}
/**
* Read from the encrypted file (input) and turn the cipher back into cleartext. Write the cleartext buffer back out
* to disk as (output) File.
*
* I left CipherInputStream in here as a test to see if I could mix it with the update() and final() methods of encrypting
* and still have a correctly decrypted file in the end. Seems to work so left it in.
*
* @param input - File object representing encrypted data on disk
* @param output - File object of cleartext data to write out after decrypting
* @throws IllegalBlockSizeException
* @throws BadPaddingException
* @throws IOException
*/
public void ReadEncryptedFile (File input, File output) throws
IllegalBlockSizeException,
BadPaddingException,
IOException
{
FileInputStream fin;
FileOutputStream fout;
CipherInputStream cin;
long totalread = 0;
int nread = 0;
byte [] inbuf = new byte [MAX_FILE_BUF];
fout = new FileOutputStream (output);
fin = new FileInputStream (input);
// creating a decoding stream from the FileInputStream above using the cipher created from setupDecrypt()
cin = new CipherInputStream (fin, mDecipher);
while ((nread = cin.read (inbuf)) > 0 )
{
Db ("read " + nread + " bytes");
totalread += nread;
// create a buffer to write with the exact number of bytes read. Otherwise a short read fills inbuf with 0x0
byte [] trimbuf = new byte [nread];
for (int i = 0; i < nread; i++)
trimbuf[i] = inbuf[i];
// write out the size-adjusted buffer
fout.write (trimbuf);
}
fout.flush();
cin.close();
fin.close ();
fout.close();
Db ("wrote " + totalread + " encrypted bytes");
}
/**
* adding main() for usage demonstration. With member vars, some of the locals would not be needed
*/
public static void main(String [] args)
{
// create the input.txt file in the current directory before continuing
File input = new File ("input.txt");
File eoutput = new File ("encrypted.aes");
File doutput = new File ("decrypted.txt");
String iv = null;
String salt = null;
Crypto en = new Crypto ("mypassword");
/*
* setup encryption cipher using password. print out iv and salt
*/
try
{
en.setupEncrypt ();
iv = Hex.encodeHexString (en.getInitVec ()).toUpperCase ();
salt = Hex.encodeHexString (en.getSalt ()).toUpperCase ();
}
catch (InvalidKeyException e)
{
e.printStackTrace();
}
catch (NoSuchAlgorithmException e)
{
e.printStackTrace();
}
catch (InvalidKeySpecException e)
{
e.printStackTrace();
}
catch (NoSuchPaddingException e)
{
e.printStackTrace();
}
catch (InvalidParameterSpecException e)
{
e.printStackTrace();
}
catch (IllegalBlockSizeException e)
{
e.printStackTrace();
}
catch (BadPaddingException e)
{
e.printStackTrace();
}
catch (UnsupportedEncodingException e)
{
e.printStackTrace();
}
/*
* write out encrypted file
*/
try
{
en.WriteEncryptedFile (input, eoutput);
System.out.printf ("File encrypted to " + eoutput.getName () + "\niv:" + iv + "\nsalt:" + salt + "\n\n");
}
catch (IllegalBlockSizeException e)
{
e.printStackTrace();
}
catch (BadPaddingException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
/*
* decrypt file
*/
Crypto dc = new Crypto ("mypassword");
try
{
dc.setupDecrypt (iv, salt);
}
catch (InvalidKeyException e)
{
e.printStackTrace();
}
catch (NoSuchAlgorithmException e)
{
e.printStackTrace();
}
catch (InvalidKeySpecException e)
{
e.printStackTrace();
}
catch (NoSuchPaddingException e)
{
e.printStackTrace();
}
catch (InvalidAlgorithmParameterException e)
{
e.printStackTrace();
}
catch (DecoderException e)
{
e.printStackTrace();
}
/*
* write out decrypted file
*/
try
{
dc.ReadEncryptedFile (eoutput, doutput);
System.out.println ("decryption finished to " + doutput.getName ());
}
catch (IllegalBlockSizeException e)
{
e.printStackTrace();
}
catch (BadPaddingException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}