创建一个NSData的类目（category）

#import <Foundation/Foundation.h>
@interface NSData (DES)
- (NSString *)base64Encoding;
+(NSString *) parseByte2HexString:(Byte *) bytes;

@end

类目方法的实现

#import "NSData+DES.h"

@implementation NSData (DES)
static const char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

- (NSString *)base64Encoding;
{
    if (self.length == 0)
        return @"";
    
    char *characters = malloc(self.length*3/2);
    
    if (characters == NULL)
        return @"";
    
    int end = self.length - 3;
    int index = 0;
    int charCount = 0;
    int n = 0;
    
    while (index <= end) {
        int d = (((int)(((char *)[self bytes])[index]) & 0x0ff) << 16) 
        | (((int)(((char *)[self bytes])[index + 1]) & 0x0ff) << 8)
        | ((int)(((char *)[self bytes])[index + 2]) & 0x0ff);
        
        characters[charCount++] = encodingTable[(d >> 18) & 63];
        characters[charCount++] = encodingTable[(d >> 12) & 63];
        characters[charCount++] = encodingTable[(d >> 6) & 63];
        characters[charCount++] = encodingTable[d & 63];
        
        index += 3;
        
        if(n++ >= 14)
        {
            n = 0;
            characters[charCount++] = ' ';
        }
    }
    
    if(index == self.length - 2)
    {
        int d = (((int)(((char *)[self bytes])[index]) & 0x0ff) << 16) 
        | (((int)(((char *)[self bytes])[index + 1]) & 255) << 8);
        characters[charCount++] = encodingTable[(d >> 18) & 63];
        characters[charCount++] = encodingTable[(d >> 12) & 63];
        characters[charCount++] = encodingTable[(d >> 6) & 63];
        characters[charCount++] = '=';
    }
    else if(index == self.length - 1)
    {
        int d = ((int)(((char *)[self bytes])[index]) & 0x0ff) << 16;
        characters[charCount++] = encodingTable[(d >> 18) & 63];
        characters[charCount++] = encodingTable[(d >> 12) & 63];
        characters[charCount++] = '=';
        characters[charCount++] = '=';
    }
    NSString * rtnStr = [[NSString alloc] initWithBytesNoCopy:characters length:charCount encoding:NSUTF8StringEncoding freeWhenDone:YES];
    return rtnStr;
}

+(NSString *) parseByte2HexString:(Byte *) bytes
{
    NSMutableString *hexStr = [[NSMutableString alloc]init];
    int i = 0;
    if(bytes)
    {
        while (bytes[i] != '\0') 
        {
            NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数
            if([hexByte length]==1)
                [hexStr appendFormat:@"0%@", hexByte];
            else 
                [hexStr appendFormat:@"%@", hexByte];
            
            i++;
        }
    }
    NSLog(@"bytes 的16进制数为:%@",hexStr);
    return hexStr;
}

+(NSString *) parseByteArray2HexString:(Byte[]) bytes
{
    NSMutableString *hexStr = [[NSMutableString alloc]init];
    int i = 0;
    if(bytes)
    {
        while (bytes[i] != '\0') 
        {
            NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数
            if([hexByte length]==1)
                [hexStr appendFormat:@"0%@", hexByte];
            else 
                [hexStr appendFormat:@"%@", hexByte];
            
            i++;
        }
    }
    NSLog(@"bytes 的16进制数为:%@",hexStr);
    return hexStr;
}

@end

创建一个管理类

#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonCrypto.h>

@interface MSEncryptUtil : NSObject
+(NSString *) encryptUseDES:(NSString *)plainText key:(NSString *)key;
@end

方法的实现

#import "NSData+DES.h"
#import "MSEncryptUtil.h"

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

@implementation MSEncryptUtil


+(NSString *) encryptUseDES:(NSString *)plainText key:(NSString *)key
{
    NSString *ciphertext = nil;
    //先编码后再加密
    plainText = [plainText stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    const char *textBytes = [plainText UTF8String];
    NSUInteger dataLength = [plainText length];
  //一个char数组
    unsigned char buffer[1024];
  //把数组全部设置为0，
    memset(buffer, 0, sizeof(char));
  //numBytesCrypted 接收加密解密后的数据的长度
    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmDES,
                                          kCCOptionPKCS7Padding,
                                          [key UTF8String], kCCKeySizeDES,
                                          iv,
                                          textBytes, dataLength,
                                          buffer, 1024,
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesEncrypted];
        ciphertext = [data base64Encoding];
    }
    return ciphertext;
}

@end

使用方法

// 从配置信息中获取参数
        NSString *userid = [[NSUserDefaults standardUserDefaults] objectForKey:@"userid"];
        NSString *token = [[NSUserDefaults standardUserDefaults] objectForKey:@"token"];
        // 加密
        NSString *loginName = [MSEncryptUtil encryptUseDES:userid key:token];