OS 采用DES--cbc方式加密字符串，为什么不同的设备输出的结果不一样？

网上找的类，拷到不同的OS设备上使用，都是加密“hello”,为什么输出的结果不一样的呢

+ (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[] = { 0x12, 0x34, 0x56, 0x78,  0x90,  0xAB,  0xCD,  0xEF };
    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;
}

const char *textBytes = [plainText UTF8String];
看看是不是这里字符编码的问题
memset(buffer, 0, sizeof(char));
这里的buffer是否一样