java实现对称加密AES与非对称加密RSA算法

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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

1.实现支持

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)

2.使用须知

(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();    }}

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