- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    NSString *hello = [self encryptUseDES:@"10036" key:AAAAA];
    NSLog(@"hello == %@",hello);
    NSLog(@"AAAAA = %@",[self decryptUseDES:hello key:AAAAA]);
}

/*字符串加密
 *参数
 *plainText : 加密明文
 *key        : 密钥 64位
 */
- (NSString *) encryptUseDES:(NSString *)plainText key:(NSString *)key
{
    NSString *ciphertext = nil;
    const char * textBytes = [plainText UTF8String];
    NSUInteger dataLength = [plainText length];
    unsigned char buffer[1024];
    memset(buffer, 0, sizeof(char));
    Byte iv[] = {1,2,3,4,5,6,7,8};
    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 = [[NSString alloc] initWithData:[GTMBase64 encodeData:data] encoding:NSUTF8StringEncoding];
    }
    return ciphertext;
}

//解密
- (NSString *) decryptUseDES:(NSString*)cipherText key:(NSString*)key
{
    NSData* cipherData = [GTMBase64 decodeString:cipherText];
    unsigned char buffer[1024];
    memset(buffer, 0, sizeof(char));
    size_t numBytesDecrypted = 0;
    Byte iv[] = {1,2,3,4,5,6,7,8};
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                          kCCAlgorithmDES,
                                          kCCOptionPKCS7Padding,
                                          [key UTF8String],
                                          kCCKeySizeDES,
                                          iv,
                                          [cipherData bytes],
                                          [cipherData length],
                                          buffer,
                                          1024,
                                          &numBytesDecrypted);
    NSString* plainText = nil;
    if (cryptStatus == kCCSuccess) {
        NSData* data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesDecrypted];
        plainText = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    }
    return plainText;
}