initWithData返回(null)

那么,我有一个选择文本的代码,并将其转换为NSData,然后使用AES-256对其进行加密,然后将此NSData转换为NSString以显示加密的消息,我按如下操作:

 NSString *text = @"This is a simple text";

    NSData* data = [text dataUsingEncoding:NSUTF8StringEncoding];

    NSData *dataEnc = [data AES256EncryptWithKey:@"12556"];

    NSString *stringCrypt = [[NSString alloc] initWithData:dataEnc encoding:NSUTF8StringEncoding];

    NSData *dataDesc = [dataEnc AES256DecryptWithKey:@"12556"];

    NSString *string = [[NSString alloc] initWithData:dataDesc encoding:NSUTF8StringEncoding];

    NSLog(@"Text normal -> %@",text);

    NSLog(@"Text with AES -> %@",stringCrypt);

    NSLog(@"Text with AES decrypted -> %@",string);

我的NSLog的输出是:

Text normal -> this is a simple text 
Text with AES -> (null) 
Text With AES decrypted -> this is a simple text

所以问题出在代码上:

NSString *stringCrypt = [[NSString alloc] initWithData:dataEnc encoding:NSUTF8StringEncoding];

这返回一个空字符串,在这种情况下,我需要将插入到文本文件的字符串,如何解决这个问题? 为什么这返回一个空值?

编辑

将其转换为AES256的功能是:

- (NSData *)AES256EncryptWithKey:(NSString *)key {
    // 'key' should be 32 bytes for AES256, will be null-padded otherwise
    char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
    bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)

    // fetch key data
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    NSUInteger dataLength = [self length];

    //See the doc: For block ciphers, the output size will always be less than or
    //equal to the input size plus the size of one block.
    //That's why we need to add the size of one block here
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);

    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
                                          keyPtr, kCCKeySizeAES256,
                                          NULL /* initialization vector (optional) */,
                                          [self bytes], dataLength, /* input */
                                          buffer, bufferSize, /* output */
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        //the returned NSData takes ownership of the buffer and will free it on deallocation
        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
    }

    free(buffer); //free the buffer;
    return nil;
}

解决了

正如用户Zaph所说的,我需要使用-base64EncodedDataWithOptions ,在我的情况下,我的操作如下:

NSString *text = @"This is a simple text";

    NSData* data = [text dataUsingEncoding:NSUTF8StringEncoding];

    NSData *dataEnc = [data AES256EncryptWithKey:@"12556"];

    NSData *daes = [dataEnc base64EncodedDataWithOptions:NSDataBase64Encoding64CharacterLineLength];

    NSString *stringCrypt = [[NSString alloc] initWithData:daes encoding:NSUTF8StringEncoding];

    NSData *decodedData = [[NSData alloc] initWithBase64EncodedString:stringCrypt options:0];

    NSData *dataDesc = [decodedData AES256DecryptWithKey:@"12556"];

    NSString *string = [[NSString alloc] initWithData:dataDesc encoding:NSUTF8StringEncoding];

    NSLog(@"Text Normal -> %@",text);

    NSLog(@"Text with AES (BASE64) -> %@",stringCrypt);

    NSLog(@"Text with AES decrypted -> %@",string);

在这种情况下,我只需要将它转换为base64字符串,现在我可以将这些值存储在文本值中,其他设备可以获取此文本并进行解密。 感谢所有。


随机字节,这就是加密的样子,无法区分,很少可以转换为字符串。 这就是为什么加密数据经常被Base64编码以产生可打印字符的原因。

使用- base64EncodedStringWithOptions:将加密数据编码为字符串。


我期望你的initWithData失败,因为dataEnc肯定不包含UTF8字节。 假设您的AES256加密代码正常工作,它将返回看起来基本上是随机的二进制数据。 它不会真实地转换为字符串,除非您按字节逐字地输入并输出十六进制值。

您可以使用其writeToFile方法之一直接将加密的NSData写入文件。

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