我需要实现256位AES加密，但是我在网上找到的所有示例都使用“ KeyGenerator”生成256位密钥，但是我想使用自己的密码。 如何创建自己的密钥？ 我尝试将其填充到256位，但是随后出现错误消息，提示密钥太长。 我确实安装了无限管辖权补丁，所以那不是问题:)
就是 KeyGenerator看起来像这样...
// Get the KeyGenerator
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(128); // 192 and 256 bits may not be available
// Generate the secret key specs.
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
编辑
我实际上是将密码填充到256个字节而不是位，这太长了。 以下是我现在正在使用的一些代码，因为我对此有更多的经验。
byte[] key = null; // TODO
byte[] input = null; // TODO
byte[] output = null;
SecretKeySpec keySpec = null;
keySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
cipher.init(Cipher.ENCRYPT_MODE, keySpec);
output = cipher.doFinal(input)
您需要自己做的“ TODO”位:-)
#1楼
通读埃里克森的建议，并拾遗什么我可以从其他几个帖子和这个例子后在这里 ，我已经尝试与建议修改更新Doug的代码。 随时进行编辑以使其更好。
- 初始化向量不再固定
- 加密密钥是使用erickson的代码派生的
- 使用SecureRandom（）在setupEncrypt（）中生成8字节盐
- 解密密钥由加密盐和密码生成
- 根据解密密钥和初始化向量生成解密密码
- 删除了十六进制旋转来代替org.apache.commons 编解码器十六进制例程
一些注意事项：它使用128位加密密钥-Java显然不会立即进行256位加密。 实现256需要在Java安装目录中安装一些额外的文件。
另外，我也不是加密货币人。 谨慎。
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();
}
}
}
#2楼
我已经在一个非常简单的课程中实现了埃里克森的答案：
Java AES 256位加密/解密类
如果获得java.security.InvalidKeyException ，则必须安装Java密码扩展（JCE）无限强度管辖区策略文件：
只需将罐子放在{JDK HOME}\\jre\\lib\\security
#3楼
使用此类进行加密。 有用。
public class ObjectCrypter {
public static byte[] encrypt(byte[] ivBytes, byte[] keyBytes, byte[] mes)
throws NoSuchAlgorithmException,
NoSuchPaddingException,
InvalidKeyException,
InvalidAlgorithmParameterException,
IllegalBlockSizeException,
BadPaddingException, IOException {
AlgorithmParameterSpec ivSpec = new IvParameterSpec(ivBytes);
SecretKeySpec newKey = new SecretKeySpec(keyBytes, "AES");
Cipher cipher = null;
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, newKey, ivSpec);
return cipher.doFinal(mes);
}
public static byte[] decrypt(byte[] ivBytes, byte[] keyBytes, byte[] bytes)
throws NoSuchAlgorithmException,
NoSuchPaddingException,
InvalidKeyException,
InvalidAlgorithmParameterException,
IllegalBlockSizeException,
BadPaddingException, IOException, ClassNotFoundException {
AlgorithmParameterSpec ivSpec = new IvParameterSpec(ivBytes);
SecretKeySpec newKey = new SecretKeySpec(keyBytes, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, newKey, ivSpec);
return cipher.doFinal(bytes);
}
}
这些是ivBytes和一个随机密钥；
String key = "e8ffc7e56311679f12b6fc91aa77a5eb";
byte[] ivBytes = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
keyBytes = key.getBytes("UTF-8");
#4楼
考虑使用Spring Security加密模块
Spring Security Crypto模块提供对对称加密，密钥生成和密码编码的支持。 该代码作为核心模块的一部分分发，但与任何其他Spring Security（或Spring）代码无关。
它提供了一个简单的加密抽象，似乎与这里的要求相符，
“标准”加密方法是使用PKCS＃5的PBKDF2（基于密码的密钥派生功能＃2）的256位AES。 此方法需要Java6。用于生成SecretKey的密码应保存在安全的地方，并且不能共享。 如果您的加密数据遭到破坏，该盐可用于防止针对密钥的字典攻击。 还应用了16字节的随机初始化向量，因此每个加密的消息都是唯一的。
如问题中所述，这还需要Java密码学扩展（JCE）无限强度管辖策略 （否则，您将遇到InvalidKeyException: Illegal Key Size ）。 可从Java 6 ， Java 7和Java 8下载 。
用法示例
import org.springframework.security.crypto.encrypt.Encryptors;
import org.springframework.security.crypto.encrypt.TextEncryptor;
import org.springframework.security.crypto.keygen.KeyGenerators;
public class CryptoExample {
public static void main(String[] args) {
final String password = "I AM SHERLOCKED";
final String salt = KeyGenerators.string().generateKey();
TextEncryptor encryptor = Encryptors.text(password, salt);
System.out.println("Salt: \"" + salt + "\"");
String textToEncrypt = "*royal secrets*";
System.out.println("Original text: \"" + textToEncrypt + "\"");
String encryptedText = encryptor.encrypt(textToEncrypt);
System.out.println("Encrypted text: \"" + encryptedText + "\"");
// Could reuse encryptor but wanted to show reconstructing TextEncryptor
TextEncryptor decryptor = Encryptors.text(password, salt);
String decryptedText = decryptor.decrypt(encryptedText);
System.out.println("Decrypted text: \"" + decryptedText + "\"");
if(textToEncrypt.equals(decryptedText)) {
System.out.println("Success: decrypted text matches");
} else {
System.out.println("Failed: decrypted text does not match");
}
}
}
并输出样本
Salt: "feacbc02a3a697b0" Original text: "*royal secrets*" Encrypted text: "7c73c5a83fa580b5d6f8208768adc931ef3123291ac8bc335a1277a39d256d9a" Decrypted text: "*royal secrets*" Success: decrypted text matches
#5楼
以下版本添加到@Wufoo的编辑中，使用InputStreams而不是文件，从而使处理各种文件更加容易。 它还将IV和Salt存储在文件的开头，因此仅需要跟踪密码。 由于IV和Salt不需要保密，因此使生活更加轻松。
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.AlgorithmParameters;
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 java.util.logging.Level;
import java.util.logging.Logger;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
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;
public class AES {
public final static int SALT_LEN = 8;
static final String HEXES = "0123456789ABCDEF";
String mPassword = null;
byte[] mInitVec = null;
byte[] mSalt = new byte[SALT_LEN];
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 AES(String password) {
mPassword = password;
}
public static String byteToHex(byte[] raw) {
if (raw == null) {
return null;
}
final StringBuilder hex = new StringBuilder(2 * raw.length);
for (final byte b : raw) {
hex.append(HEXES.charAt((b & 0xF0) >> 4)).append(HEXES.charAt((b & 0x0F)));
}
return hex.toString();
}
public static byte[] hexToByte(String hexString) {
int len = hexString.length();
byte[] ba = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
ba[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4)
+ Character.digit(hexString.charAt(i + 1), 16));
}
return ba;
}
/**
* debug/print messages
* @param msg
*/
private void Db(String msg) {
System.out.println("** Crypt ** " + msg);
}
/**
* 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(InputStream inputStream, OutputStream outputStream)
throws IOException, IllegalBlockSizeException, BadPaddingException {
try {
long totalread = 0;
int nread = 0;
byte[] inbuf = new byte[MAX_FILE_BUF];
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 :" + byteToHex(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 :" + byteToHex(mInitVec));
outputStream.write(mSalt);
outputStream.write(mInitVec);
while ((nread = inputStream.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[] tmpBuf = mEcipher.update(trimbuf);
// I don't think this should happen, but just in case..
if (tmpBuf != null) {
outputStream.write(tmpBuf);
}
}
// finalize the encryption since we've done it in blocks of MAX_FILE_BUF
byte[] finalbuf = mEcipher.doFinal();
if (finalbuf != null) {
outputStream.write(finalbuf);
}
outputStream.flush();
inputStream.close();
outputStream.close();
outputStream.close();
Db("wrote " + totalread + " encrypted bytes");
} catch (InvalidKeyException ex) {
Logger.getLogger(AES.class.getName()).log(Level.SEVERE, null, ex);
} catch (InvalidParameterSpecException ex) {
Logger.getLogger(AES.class.getName()).log(Level.SEVERE, null, ex);
} catch (NoSuchAlgorithmException ex) {
Logger.getLogger(AES.class.getName()).log(Level.SEVERE, null, ex);
} catch (NoSuchPaddingException ex) {
Logger.getLogger(AES.class.getName()).log(Level.SEVERE, null, ex);
} catch (InvalidKeySpecException ex) {
Logger.getLogger(AES.class.getName()).log(Level.SEVERE, null, ex);
}
}
/**
* 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(InputStream inputStream, OutputStream outputStream)
throws IllegalBlockSizeException, BadPaddingException, IOException {
try {
CipherInputStream cin;
long totalread = 0;
int nread = 0;
byte[] inbuf = new byte[MAX_FILE_BUF];
// Read the Salt
inputStream.read(this.mSalt);
Db("generated salt :" + byteToHex(mSalt));
SecretKeyFactory factory = null;
SecretKey tmp = null;
SecretKey secret = null;
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");
// Set the appropriate size for mInitVec by Generating a New One
AlgorithmParameters params = mDecipher.getParameters();
mInitVec = params.getParameterSpec(IvParameterSpec.class).getIV();
// Read the old IV from the file to mInitVec now that size is set.
inputStream.read(this.mInitVec);
Db("mInitVec is :" + byteToHex(mInitVec));
mDecipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(mInitVec));
// creating a decoding stream from the FileInputStream above using the cipher created from setupDecrypt()
cin = new CipherInputStream(inputStream, 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
outputStream.write(trimbuf);
}
outputStream.flush();
cin.close();
inputStream.close();
outputStream.close();
Db("wrote " + totalread + " encrypted bytes");
} catch (Exception ex) {
Logger.getLogger(AES.class.getName()).log(Level.SEVERE, null, ex);
}
}
/**
* 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;
AES en = new AES("mypassword");
/*
* write out encrypted file
*/
try {
en.WriteEncryptedFile(new FileInputStream(input), new FileOutputStream(eoutput));
System.out.printf("File encrypted to " + eoutput.getName() + "\niv:" + iv + "\nsalt:" + salt + "\n\n");
} catch (IllegalBlockSizeException | BadPaddingException | IOException e) {
e.printStackTrace();
}
/*
* decrypt file
*/
AES dc = new AES("mypassword");
/*
* write out decrypted file
*/
try {
dc.ReadEncryptedFile(new FileInputStream(eoutput), new FileOutputStream(doutput));
System.out.println("decryption finished to " + doutput.getName());
} catch (IllegalBlockSizeException | BadPaddingException | IOException e) {
e.printStackTrace();
}
}
}
来源：oschina
链接：https://my.oschina.net/u/3797416/blog/3165837