android 应用AES技术加密/解密字符串

最新推荐文章于 2022-10-30 09:05:48 发布

转载最新推荐文章于 2022-10-30 09:05:48 发布 · 689 阅读

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#加密 #解密 #android #byte #string #exception

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本文介绍了使用AES算法进行字符串的加密与解密过程，包括密钥生成、加密与解密方法实现，以及如何将原始文本转换为十六进制字符串和从十六进制字符串还原文本。

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package common;

import java.security.SecureRandom;   

import javax.crypto.Cipher;   
import javax.crypto.KeyGenerator;   
import javax.crypto.SecretKey;   
import javax.crypto.spec.SecretKeySpec;   
  
/**  
 加密 – 
 1.String encryptingCode = SimpleCrypto.encrypt(masterPassword,originalText);


解密 – 
 1.String originalText = SimpleCrypto.decrypt(masterpassword, encryptingCode);


 masterpassword: 密码。
 encryptingCode：加密后的字符串。
 originalText: 需要加密的字符串。
 */  
public class AES {   
  
    public static String encrypt(String seed, String cleartext) throws Exception {   
        byte[] rawKey = getRawKey(seed.getBytes());   
        byte[] result = encrypt(rawKey, cleartext.getBytes());   
        return toHex(result);   
    }   
       
    public static String decrypt(String seed, String encrypted) throws Exception {   
        byte[] rawKey = getRawKey(seed.getBytes());   
        byte[] enc = toByte(encrypted);   
        byte[] result = decrypt(rawKey, enc);   
        return new String(result);   
    }   
  
    private static byte[] getRawKey(byte[] seed) throws Exception {   
        KeyGenerator kgen = KeyGenerator.getInstance("AES");   
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");   
        sr.setSeed(seed);   
        kgen.init(128, sr); // 192 and 256 bits may not be available   
        SecretKey skey = kgen.generateKey();   
        byte[] raw = skey.getEncoded();   
        return raw;   
    }   
  
       
    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {   
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");   
        Cipher cipher = Cipher.getInstance("AES");   
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);   
        byte[] encrypted = cipher.doFinal(clear);   
        return encrypted;   
    }   
  
    private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {   
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");   
        Cipher cipher = Cipher.getInstance("AES");   
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);   
        byte[] decrypted = cipher.doFinal(encrypted);   
        return decrypted;   
    }   
  
    public static String toHex(String txt) {   
        return toHex(txt.getBytes());   
    }   
    public static String fromHex(String hex) {   
        return new String(toByte(hex));   
    }   
       
    public static byte[] toByte(String hexString) {   
        int len = hexString.length()/2;   
        byte[] result = new byte[len];   
        for (int i = 0; i < len; i++)   
            result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();   
        return result;   
    }   
  
    public static String toHex(byte[] buf) {   
        if (buf == null)   
            return "";   
        StringBuffer result = new StringBuffer(2*buf.length);   
        for (int i = 0; i < buf.length; i++) {   
            appendHex(result, buf[i]);   
        }   
        return result.toString();   
    }   
    private final static String HEX = "0123456789ABCDEF";   
    private static void appendHex(StringBuffer sb, byte b) {   
        sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));   
    }   
       
}

原文地址:http://hi.baidu.com/1018834925/blog/item/62a6c146b869ad24869473c1.html