des对称加密和解密

1.des对称加密，是一种比较传统的加密方式，其加密运算、解密运算使用的是同样的密钥，信息的发送者和信息的接收者在进行信息的传输与处理时，必须共同持有该对称密码，是一种对称加密算法。

源码链接 ：https://gitee.com/xuanTestApp/testApp.git

2. ************** WHDesOperation.h文件



//

//  WHDesOperation.h

//  DesEncryption

//

//  Created by weihong xuan on 2015/12/14.

//  Copyright © 2015年 weihong xuan. All rights reserved.

//



#import <Foundation/Foundation.h>



@interface WHDesOperation : NSObject

/**

 *  对NSString进行des对称加密

 *

 *  @param plainText  要加密的字符串

 *  @param key        加密的key

 *  @param randomFlag 加密时是否要包含随机数

 *

 *  @return 加密后的字符串

 */

+ (NSString *)encryptUseDES:(NSString*)plainText key:(NSString *)key isHaveRandomNumber:(BOOL)randomFlag;



/**

 *  解密字符串

 *

 *  @param cipherText 密文字符串

 *  @param key        加密的key

 *  @param randomFlag 加密时是否要包含随机数

 *

 *  @return 解密后的字符串

 */

+ (NSString *)decryptUseDES:(NSString*)cipherText key:(NSString*)key isHaveRandomNumber:(BOOL)randomFlag;

@end



3. ************** WHDesOperation.m文件



//

//  WHDesOperation.m

//  DesEncryption

//

//  Created by weihong xuan on 2015/12/14.

//  Copyright © 2015年 weihong xuan. All rights reserved.

//



#import "WHDesOperation.h"

#import <CommonCrypto/CommonCrypto.h>

#import "GTMBase64.h"



@implementation WHDesOperation

//加密

+ (NSString *)encryptUseDES:(NSString*)plainText key:(NSString *)key isHaveRandomNumber:(BOOL)randomFlag{

    NSString *ciphertext = nil;

    

    NSString *charactersToEscape =@"?!@#$^&%*+,:;='\"`<>()[]{}/\\| ";

    NSCharacterSet *allowedCharacters = [[NSCharacterSetcharacterSetWithCharactersInString:charactersToEscape]invertedSet];

    plainText = [plainText stringByAddingPercentEncodingWithAllowedCharacters:allowedCharacters];

    const char *textBytes = [plainTextUTF8String];

    NSUInteger dataLength = [plainText length];

    unsigned char buffer[1024];

    memset(buffer, 0, sizeof(char));

    CCCryptorStatus cryptStatus;

    size_t numBytesEncrypted = 0;

    if (randomFlag) {

        Byte iv[] = {1,2,3,4,5,6,7,8};

        cryptStatus = CCCrypt(kCCEncrypt,kCCAlgorithmDES,

                              kCCOptionPKCS7Padding,

                              [key UTF8String],kCCKeySizeDES,

                              iv,

                              textBytes, dataLength,

                              buffer, 1024,

                              &numBytesEncrypted);

    }else{

        cryptStatus = CCCrypt(kCCEncrypt,kCCAlgorithmDES,

                              kCCOptionPKCS7Padding |kCCOptionECBMode,

                              [key UTF8String],kCCKeySizeDES,

                              nil,

                              textBytes, dataLength,

                              buffer, dataLength + kCCBlockSizeAES128,

                              &numBytesEncrypted);

    }

    if (cryptStatus == kCCSuccess) {

        NSData *data = [NSDatadataWithBytes:bufferlength:(NSUInteger)numBytesEncrypted];

        ciphertext = [[NSStringalloc]initWithData:[GTMBase64encodeData:data]encoding:NSUTF8StringEncoding];

    }

    return ciphertext;

}



//解密

+ (NSString *)decryptUseDES:(NSString*)cipherText key:(NSString*)key isHaveRandomNumber:(BOOL)randomFlag{

    NSData* cipherData = [GTMBase64decodeString:cipherText];

    unsigned char buffer[1024];

    memset(buffer, 0, sizeof(char));

    size_t numBytesDecrypted = 0;

    CCCryptorStatus cryptStatus;

    if (randomFlag) {

        Byte iv[] = {1,2,3,4,5,6,7,8};

        cryptStatus = CCCrypt(kCCDecrypt,

                              kCCAlgorithmDES,

                              kCCOptionPKCS7Padding,

                              [key UTF8String],

                              kCCKeySizeDES,

                              iv,

                              [cipherData bytes],

                              [cipherData length],

                              buffer,

                              1024,

                              &numBytesDecrypted);

    }else{

        cryptStatus = CCCrypt(kCCDecrypt,

                              kCCAlgorithmDES,

                              kCCOptionPKCS7Padding |kCCOptionECBMode,

                              [key UTF8String],

                              kCCKeySizeDES,

                              nil,

                              [cipherData bytes],

                              [cipherData length],

                              buffer,

                              [cipherData length] +kCCBlockSizeAES128,

                              &numBytesDecrypted);

    }

    NSString* plainText = nil;

    if (cryptStatus == kCCSuccess) {

        NSData* data = [NSDatadataWithBytes:bufferlength:(NSUInteger)numBytesDecrypted];

        plainText = [[NSStringalloc]initWithData:dataencoding:NSUTF8StringEncoding];

        plainText = [plainText stringByRemovingPercentEncoding];

    }

    return plainText;

}

@end



4.****************  使用



//

//  ViewController.m

//  DesEncryption

//

//  Created by weihong xuan on 2015/12/14.

//  Copyright © 2015年 weihong xuan. All rights reserved.

//



#import "ViewController.h"

#import "WHDesOperation.h"





@interface ViewController ()



@end



@implementation ViewController



- (void)viewDidLoad {

    [superviewDidLoad];



    NSString * testStr = @"要加密的字符 ^&%*+";

    NSString * desKey =@"密码123456";//加密运算、解密运算时所使用的密钥

    

    NSString * encStr = [WHDesOperationencryptUseDES:testStrkey:desKeyisHaveRandomNumber:YES];

    NSLog(@"加密后的字符串：%@",encStr);

    

    NSString * decStr = [WHDesOperationdecryptUseDES:encStrkey:@"123"isHaveRandomNumber:YES];

    NSLog(@"密码错误时解密后的字符串：%@",decStr);



    decStr = [WHDesOperationdecryptUseDES:encStrkey:@"密码123456"isHaveRandomNumber:NO];

    NSLog(@"密码正确时随机数错误时 解密后的字符串：%@",decStr);



    decStr = [WHDesOperationdecryptUseDES:encStrkey:@"密码123456"isHaveRandomNumber:YES];

    NSLog(@"正确解密后的字符串：%@",decStr);

}

- (void)didReceiveMemoryWarning {

    [superdidReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

@end