AES加密

我就是我 2023-10-03 17:58 3阅读 0赞

## 一、AES是什么 ##

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。2006年，已然成为对称密钥加密中最流行的算法之一。  
主要分为五种工作体制：1.电码本模式（Electronic Codebook Book (ECB)）；2.密码分组链接模式（Cipher Block Chaining (CBC)）；3.计算器模式（Counter (CTR)）；4.密码反馈模式（Cipher FeedBack (CFB)）；5.输出反馈模式（Output FeedBack (OFB)）。

## 二、AES如何使用 ##

import java.util.Arrays;
    import java.util.Random;
    import javax.crypto.Cipher;
    import javax.crypto.spec.IvParameterSpec;
    import javax.crypto.spec.SecretKeySpec;
    import org.apache.commons.codec.binary.Hex;
    
    //工具类直接调用即可
    public class AESUtil {
        
    
    	private static byte[] getNRawKey(String seed, int size) throws Exception {
        
    		byte[] s = seed.getBytes("utf-8");
    		Random sr = new Random();
    		sr.setSeed(Arrays.hashCode(s));
    		byte[] r = new byte[size];
    		sr.nextBytes(r);
    		return r;
    	}
    	//传入字符串密钥和数据加密，不需要指定Iv(偏移量),返回结果使用hex编码
    	public static String nEncrypt(String seed, String cleartext) throws Exception {
        
    		System.out.print(seed + "-");
    		byte[] result = nEncrypt(getNRawKey(seed, 16), cleartext.getBytes("utf-8"));
    		return Hex.encodeHexString(result);
    	}
    	//传入字符串密钥和加密后数据解密，不需要指定Iv(偏移量)
    	public static String nDecrypt(String seed, String encrypted) throws Exception {
        
    		byte[] r = nDecrypt(getNRawKey(seed, 16), Hex.decodeHex(encrypted.toCharArray()));
    		return new String(r, "utf-8");
    	}
    	//传入字节密钥和数据进行加密，不需要指定Iv(偏移量),返回结果使用hex编码
    	public static byte[] nEncrypt(byte[] raw, byte[] clear) throws Exception {
        
    		SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    		Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
    		cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
    		byte[] encrypted = cipher.doFinal(clear);
    		return encrypted;
    	}
    	//传入字节密钥和加密后数据解密，不需要指定Iv(偏移量
    	public static byte[] nDecrypt(byte[] raw, byte[] encrypted) throws Exception {
        
    		SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    		Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
    
    		cipher.init(Cipher.DECRYPT_MODE, skeySpec);
    		byte[] decrypted = cipher.doFinal(encrypted);
    		return decrypted;
    	}
    	//传入字节密钥和数据进行加密，需要指定Iv(偏移量),NoPadding不能自动填补iv和密钥缺少字节
    	public static byte[] encryptWithZero(byte[] key, byte[] iv, byte[] input) throws Exception {
        
    		int p = input.length % key.length;
    		if (p != 0) {
        
    			byte[] tmp = new byte[input.length + key.length - p];
    			System.arraycopy(input, 0, tmp, 0, input.length);
    			Arrays.fill(tmp, input.length, tmp.length, (byte) 0);
    			input = tmp;
    		}
    
    		SecretKeySpec keySpec = new SecretKeySpec(key, "AES");
    		IvParameterSpec ivSpec = new IvParameterSpec(iv);
    		Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
    		cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);
    		byte[] encrypted = cipher.doFinal(input);
    		return encrypted;
    	}
    
    	private static byte[] unpad0(byte[] in) {
        
    		byte[] upData = in;
    		int index = in.length - 1;
    		for (; index >= 0; index--) {
        
    			if (in[index] != 0) {
        
    				break;
    			}
    		}
    
    		if (index != in.length - 1) {
        
    			upData = new byte[index + 1];
    			System.arraycopy(in, 0, upData, 0, upData.length);
    		}
    		return upData;
    	}
    	//传入字节密钥和数据进行解密，需要指定Iv(偏移量),NoPadding不能自动填补iv和密钥缺少字节
    	public static byte[] decryptWithZero(byte[] key, byte[] iv, byte[] input) throws Exception {
        
    		SecretKeySpec keySpec = new SecretKeySpec(key, "AES");
    		IvParameterSpec ivSpec = new IvParameterSpec(iv);
    		Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
    		cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
    		byte[] decrypted = cipher.doFinal(input);
    		decrypted = unpad0(decrypted);
    		return decrypted;
    	}
    }

## 三、使用时踩过的坑 ##

如果使用NOPadding，在写密钥和偏移量时，要注意字节大小是16的倍数，否则会报错，建议写的时候使用下面代码查一下字节长度。

System.out.println("miyao".getBytes().length);