有时候项目可能要用到加解密，以此来保护用户数据的安全性。下面我就来介绍AES的加解密。闲话不多说，直接上代码。

    //  
    //  ViewController.m  
    //  test  
    //  
    //  Created by yons on 14-8-7.  
    //  Copyright (c) 2014年 yons. All rights reserved.  
    //  
      
    #import "ViewController.h"  
    #import "TableViewController.h"  
    #import "SecurityUtil.h"  
    #import "GTMBase64.h"  
      
    #define KEY @"ABCDEFGHIJKLMNOP" //key可修改  
      
    @interface ViewController ()  
    {  
        UIButton *encryption;  
        UIButton *decrypt;  
        UITextField *content;  
          
        UILabel *Before;  
        UILabel *after;  
        UILabel *key;  
    }  
      
    @end  
      
      
      
    @implementation ViewController  
      
    - (void)viewDidLoad  
    {  
        [super viewDidLoad];  
        // Do any additional setup after loading the view, typically from a nib.  
          
        self.view.backgroundColor = [UIColor whiteColor];  
          
        content = [[UITextField alloc] initWithFrame:CGRectMake(20, 60, 280, 40)];  
        content.backgroundColor = [UIColor whiteColor];  
        [self setBorder:content.layer];  
        content.placeholder = @" 请输入加密或解密的字符串";  
         
        [self.view addSubview:content];  
          
         encryption = [[UIButton alloc] initWithFrame:CGRectMake(60, 125,80, 40)];  
        [encryption setTitle:@"加密" forState:UIControlStateNormal] ;  
        encryption.backgroundColor = [UIColor blackColor];  
        [encryption addTarget:self action:@selector(Encryption) forControlEvents:UIControlEventTouchUpInside];  
        [self.view addSubview:encryption];  
          
         decrypt = [[UIButton alloc] initWithFrame:CGRectMake(175, 125,80, 40)];  
        [decrypt setTitle:@"解密" forState:UIControlStateNormal] ;  
         decrypt.backgroundColor = [UIColor blackColor];  
        [decrypt addTarget:self action:@selector(Decrypt) forControlEvents:UIControlEventTouchUpInside];  
        [self.view addSubview:decrypt];  
          
        key = [[UILabel alloc] initWithFrame:CGRectMake(20, 190, 290, 20)];  
        Before = [[UILabel alloc] initWithFrame:CGRectMake(20, 220, 290, 40)];  
        Before.lineBreakMode = YES;  
        Before.numberOfLines = 0;  
         
        after = [[UILabel alloc] initWithFrame:CGRectMake(20, 270, 280, 40)];  
        after.lineBreakMode = YES;  
        after.numberOfLines = 0;  
          
        [key setFont:[UIFont fontWithName:@"Arial" size:14]];  
        [Before setFont:[UIFont fontWithName:@"Arial" size:14]];  
        [after setFont:[UIFont fontWithName:@"Arial" size:14]];  
          
        [self.view addSubview:key];  
        [self.view addSubview:Before];  
        [self.view addSubview:after];  
    }  
      
    // 加边框  
    - (void) setBorder: (CALayer*) layer  
    {  
        [layer setMasksToBounds:YES];  
        [layer setCornerRadius:5.0]; //设置矩圆角半径  
        [layer setBorderWidth:0.7];   //边框宽度  
        [layer setBorderColor:[[UIColor lightGrayColor] CGColor]];  
    }  
      
    //加密  
    - (void) Encryption  
    {  
        if ([content.text isEqualToString:@""])  
        {  
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"温馨提示！" message:@"亲，你还没有输入任何内容！" delegate:self cancelButtonTitle:@"确 定" otherButtonTitles:nil, nil nil];  
            [alert show];  
        }  
        else  
        {  
            NSString *string = [SecurityUtil encryptAESData:content.text app_key:KEY];  
            key.text = [NSString stringWithFormat:@"加密key：%@",KEY];  
            Before.text = [NSString stringWithFormat:@"加密前：%@",content.text];  
            after.text = [NSString stringWithFormat:@"加密后：%@",string];  
              
            NSLog(@"string：%@", string);  
        }  
         
    }  
      
    //解密  
    - (void) Decrypt  
    {  
        if ([content.text isEqualToString:@""])  
        {  
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"温馨提示！" message:@"亲，你还没有输入任何内容！" delegate:self cancelButtonTitle:@"确 定" otherButtonTitles:nil, nil nil];  
            [alert show];  
        }  
        else  
        {  
            NSData *EncryptData = [GTMBase64 decodeString:content.text]; //解密前进行GTMBase64编码  
            NSString * string = [SecurityUtil decryptAESData:EncryptData app_key:KEY];  
              
            key.text = [NSString stringWithFormat:@"解密key：%@",KEY];  
            Before.text = [NSString stringWithFormat:@"解密前：%@",content.text];  
              
            if ([string isEqualToString:@""] | [string isEqualToString:nil]) {  
                string = @"解密失败，亲，请输入加密后的字符串！";  
            }  
            after.text = [NSString stringWithFormat:@"解密后：%@",string];  
              
            NSLog(@"string：%@", string);  
        }  
    }  
      
      
    - (void)didReceiveMemoryWarning  
    {  
        [super didReceiveMemoryWarning];  
        // Dispose of any resources that can be recreated.  
    }  
      
    @end  

最后附上Demo的下载地址： AES加解密Demo（点击下载）

来自：http://blog.csdn.net/by3g123/article/details/44617201