本文共 9494 字，大约阅读时间需要 31 分钟。
AES高级加密标准（英语：Advanced Encryption Standard，缩写：AES），在密码学中又称Rijndael加密法，是美国联邦政府采用的一种区块加密标准。这个标准用来替代原先的DES，已经被多方分析且广为全世界所使用。
JDK AES实现
AES理论上支持128,192,256三种长度的密钥，几乎全部密码块工作模式和填充方法，但JDK 7中只实现如下四种AES加密算法：
(1)AES/CBC/NoPadding (128)
(2)AES/CBC/PKCS5Padding (128) (3)AES/ECB/NoPadding (128) (4)AES/ECB/PKCS5Padding (128)(1)缺省模式和填充为“AES/ECB/PKCS5Padding”，Cipher.getInstance(“AES”)与Cipher.getInstance(“AES/ECB/PKCS5Padding”)等效。
(2)JDK的PKCS5Padding实际是上述的PKCS7的实现。
(3)由于AES是按照16Byte为块进行处理，对于NoPadding而言，如果需要加密的原文长度不是16Byte的倍数，将无法处理抛出异常，其实是由用户自己选择Padding的算法。密文则必然是16Byte的倍数，否则密文肯定异常。
(4)如果加密为PKCS5Padding，解密可以选择NoPadding，也能解密成功，内容为原文加上PKCS5Padding之后的结果。
(5)如果原文最后一个字符为>=0x00&&<=0x10的内容，PKCS5Padding的解密将会出现异常，要么是符合PKCS5Padding，最后的内容被删除，要么不符合，则解密失败抛出异常。对此有两种思路，一是原文通过Base64编码为可见字符，二是原文自带长度使用NoPadding解密。
代码：
package com.bohua.test;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.security.InvalidKeyException;import java.security.Key;import java.security.NoSuchAlgorithmException;import java.security.SecureRandom;import javax.crypto.BadPaddingException;import javax.crypto.Cipher;import javax.crypto.IllegalBlockSizeException;import javax.crypto.KeyGenerator;import javax.crypto.NoSuchPaddingException;import javax.crypto.ShortBufferException;/** * @author bohua *对称技术只有一把秘钥,所以秘钥的管理是一个很麻烦的问题 */public class AES { private Key key; /** * 生成AES对称秘钥 * @throws NoSuchAlgorithmException */ public void generateKey() throws NoSuchAlgorithmException { KeyGenerator keygen = KeyGenerator.getInstance("AES"); SecureRandom random = new SecureRandom(); keygen.init(random); this.key = keygen.generateKey(); } /** * 加密 * @param in * @param out * @throws InvalidKeyException * @throws ShortBufferException * @throws IllegalBlockSizeException * @throws BadPaddingException * @throws NoSuchAlgorithmException * @throws NoSuchPaddingException * @throws IOException */ public void encrypt(InputStream in, OutputStream out) throws InvalidKeyException, ShortBufferException, IllegalBlockSizeException, BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException, IOException { this.crypt(in, out, Cipher.ENCRYPT_MODE); } /** * 解密 * @param in * @param out * @throws InvalidKeyException * @throws ShortBufferException * @throws IllegalBlockSizeException * @throws BadPaddingException * @throws NoSuchAlgorithmException * @throws NoSuchPaddingException * @throws IOException */ public void decrypt(InputStream in, OutputStream out) throws InvalidKeyException, ShortBufferException, IllegalBlockSizeException, BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException, IOException { this.crypt(in, out, Cipher.DECRYPT_MODE); } /** * 实际的加密解密过程 * @param in * @param out * @param mode * @throws IOException * @throws ShortBufferException * @throws IllegalBlockSizeException * @throws BadPaddingException * @throws NoSuchAlgorithmException * @throws NoSuchPaddingException * @throws InvalidKeyException */ public void crypt(InputStream in, OutputStream out, int mode) throws IOException, ShortBufferException, IllegalBlockSizeException, BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException { Cipher cipher = Cipher.getInstance("AES"); cipher.init(mode, this.key); int blockSize = cipher.getBlockSize(); int outputSize = cipher.getOutputSize(blockSize); byte[] inBytes = new byte[blockSize]; byte[] outBytes = new byte[outputSize]; int inLength = 0; boolean more = true; while (more) { inLength = in.read(inBytes); if (inLength == blockSize) { int outLength = cipher.update(inBytes, 0, blockSize, outBytes); out.write(outBytes, 0, outLength); } else { more = false; } } if (inLength > 0) outBytes = cipher.doFinal(inBytes, 0, inLength); else outBytes = cipher.doFinal(); out.write(outBytes); out.flush(); } public void setKey(Key key) { this.key = key; } public Key getKey() { return key; }} RSA是目前最有影响力的公钥加密算法，它能够抵抗到目前为止已知的绝大多数密码攻击，已被ISO推荐为公钥数据加密算法。
RSA算法是一种非对称密码算法，所谓非对称，就是指该算法需要一对密钥，使用其中一个加密，则需要用另一个才能解密。
由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密.
非对称加密算法可以用来对对称加密的密钥加密，这样保证密钥的安全也就保证了数据的安全。
代码：
package com.bohua.test;import java.security.InvalidKeyException;import java.security.Key;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.NoSuchAlgorithmException;import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.IllegalBlockSizeException;import javax.crypto.NoSuchPaddingException;/** * @author bohua *由于非对称加密算法的开销很大,所以如果直接以非对称技术来加密发送的消息效率会很差. */public class RSA { public static final int KEYSIZE = 512; private KeyPair keyPair; private Key publicKey; private Key privateKey; /** * 生成秘钥对 * @return * @throws NoSuchAlgorithmException */ public KeyPair generateKeyPair() throws NoSuchAlgorithmException { KeyPairGenerator pairgen = KeyPairGenerator.getInstance("RSA"); SecureRandom random = new SecureRandom(); pairgen.initialize(RSA.KEYSIZE, random); this.keyPair = pairgen.generateKeyPair(); return this.keyPair; } /** * 加密秘钥 * @param key * @return * @throws NoSuchAlgorithmException * @throws NoSuchPaddingException * @throws InvalidKeyException * @throws IllegalBlockSizeException */ public byte[] wrapKey(Key key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException { Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.WRAP_MODE, this.privateKey); byte[] wrappedKey = cipher.wrap(key); return wrappedKey; } /** * 解密秘钥 * @param wrapedKeyBytes * @return * @throws NoSuchAlgorithmException * @throws NoSuchPaddingException * @throws InvalidKeyException */ public Key unwrapKey(byte[] wrapedKeyBytes) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException { Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.UNWRAP_MODE, this.publicKey); Key key = cipher.unwrap(wrapedKeyBytes, "AES", Cipher.SECRET_KEY); return key; } public Key getPublicKey() { return publicKey; } public void setPublicKey(Key publicKey) { this.publicKey = publicKey; } public Key getPrivateKey() { return privateKey; } public void setPrivateKey(Key privateKey) { this.privateKey = privateKey; }} 测试类：
package com.bohua.test;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.security.InvalidKeyException;import java.security.Key;import java.security.KeyPair;import java.security.NoSuchAlgorithmException;import javax.crypto.BadPaddingException;import javax.crypto.IllegalBlockSizeException;import javax.crypto.NoSuchPaddingException;import javax.crypto.ShortBufferException;/** * 对称秘钥与非对称密钥结合 * @author bohua * */public class Test { public Test(){ //模仿加密 try { InputStream in=new FileInputStream("D:\\Documents and Settings\\bohua\\桌面\\新建 文本文档 (2).txt"); OutputStream out=new FileOutputStream("D:\\Documents and Settings\\bohua\\桌面\\新建 文本文档 (3).txt"); AES aes=new AES(); RSA rsa=new RSA(); aes.generateKey();//获得key Key key=aes.getKey(); System.out.println(key+" kkkkk"); //获取非对称秘钥 KeyPair keyPair=rsa.generateKeyPair(); rsa.setPrivateKey(keyPair.getPrivate()); byte[] b=rsa.wrapKey(key); aes.encrypt(in, out);//加密过程 Decrypt(b,keyPair); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InvalidKeyException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ShortBufferException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalBlockSizeException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (BadPaddingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (NoSuchAlgorithmException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (NoSuchPaddingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } /** 模仿解密过程 * @param b * @param keyPair */ private void Decrypt(byte[] b, KeyPair keyPair) { InputStream in2; try { in2 = new FileInputStream("D:\\Documents and Settings\\bohua\\桌面\\新建 文本文档 (3).txt"); OutputStream out2=new FileOutputStream("D:\\Documents and Settings\\bohua\\桌面\\新建 文本文档 (4).txt"); AES aes2=new AES(); RSA rsa2=new RSA(); rsa2.setPublicKey(keyPair.getPublic()); Key key2=rsa2.unwrapKey(b); aes2.setKey(key2); aes2.decrypt(in2,out2); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InvalidKeyException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (NoSuchAlgorithmException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (NoSuchPaddingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ShortBufferException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalBlockSizeException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (BadPaddingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static void main(String[] args) { new Test(); }} 无意中发现了一个巨牛的人工智能教程，忍不住分享一下给大家。教程不仅是零基础，通俗易懂，而且非常风趣幽默，像看小说一样！觉得太牛了，所以分享给大家。可以跳转到教程。
转载地址：http://tglgb.baihongyu.com/