NSData的将不接受有效的base64 EN codeD字符串 [英] NSData won't accept valid base64 encoded string

问题描述

我实施在iOS（7）cient端JSON网络令牌认证。它的工作很好。我的应用程序rceives令牌，并且可以使我的服务器进行身份验证调用它们。

现在，我希望我的客户端code检查令牌上的到期日，因此它可以知道什么时候才能重新验证。检查在JWT验证令牌的截止日期是简单的。授权令牌的base64 3 EN codeD JSON斑点，由分离'。 - 到期时间戳是在中间的blob，在一个名为字段外部。这是自秒Unix纪元。

所以，我的code在寻找像这样：

   - （*的NSDate）EXPIRATIONDATE
{
    如果（_tokenAppearsValid！）回零;    如果（！_parsedExpirationDate）
    {
        //
        //令牌为三的base64连接相隔codeD有效载荷。
        //我们想要的有效载荷是中间的一个，这是一个JSON字典，以
        //EXP'是到期日期的UNIX时间戳秒
        //返回nil是合适的，如果没有'记录'是容易找到
        //        的NSArray *成分= [self.token componentsSeparatedByString：。@];        的NSString *有效载荷=分量[1];        NSData的* payloadJsonData = [[NSData的页头]
            initWithBase64En codedString：有效载荷
            选项​​：NSDataBase64DecodingIgnoreUnknownCharacters];        NSError * jsonError =零;
        *的NSDictionary = payloadJson [NSJSONSerialization JSONObjectWithData：payloadJsonData选项：0错误：＆放大器; jsonError]。
        如果（payloadJson）
        {
            如果（payloadJson [@EXP]）
            {
                NSTimeInterval timestampSeconds = [payloadJson [@EXP]的doubleValue];
                _expirationDate = [NSDate的dateWithTimeIntervalSince1970：timestampSeconds];
            }
        }        _parsedExpirationDate = YES;
    }    返回_expirationDate;
}
 

问题是简单的。中间的base64一滴，当NSData的-initWithBase64En codedString解析为无 - 而这是很糟糕。

我检查中的Base64的blob，它似乎是有效的。我的服务器的返回空数据的时刻所以这里是一个例子斑点：
    <$c$c>eyJlbWFpbCI6ImZvb0BiYXIuYmF6IiwiYWNjb3VudElkIjoiMTIzNDUtNjc4OTAtYmFyLWJheiIsImV4cCI6MTM5MDkxNTAzNywiaWF0IjoxMzkwOTE0MTM3fQ

据德codeS为：

<$p$p><$c$c>{\"email\":\"[e-mail]\",\"accountId\":\"12345-67890-bar-baz\",\"exp\":1390915037,\"iat\":1390914137}

我测试了它在这里： HTTP：//www.base64de$c$c.org

我用的NSData的方法的base64在elswhere我的应用程序的成功 - 我不认为我在做什么特别在这里打破。但我所有的耳朵！任何想法？

解决方案

您Base64编码字符串无效。它必须以 = 字符都被填充
的长度是4的倍数在您的情况：eyJlbWFp .... MTM3fQ ==

通过这种填充， initWithBase64En codedString 德codeS中的Base64字符串正确。

I'm implementing JSON Web Token authentication on the iOS (7) cient-side. It's working nicely. My app rceives tokens, and can make authenticated calls to my server with them.

Now, I want my client side code to check for an expiration date on the token so it can know when to re-authenticate. Checking for the expiration date on a JWT auth token is straightforward. The authorization token is 3 base64 encoded JSON blobs, separated by a '.' - The expiration timestamp is in the middle blob, in a field called ext. It's seconds since unix epoch.

So my code's looking like so:

- (NSDate*) expirationDate
{
    if ( !_tokenAppearsValid ) return nil;

    if ( !_parsedExpirationDate )
    {
        //
        //  Token is three base64 encoded payloads separated by '.'
        //  The payload we want is the middle one, which is a JSON dict, with
        //  'exp' being the unix seconds timestamp of the expiration date
        //  Returning nil is appropriate if no 'exp' is findable
        //

        NSArray *components = [self.token componentsSeparatedByString:@"."];

        NSString *payload = components[1];

        NSData* payloadJsonData = [[NSData alloc]
            initWithBase64EncodedString:payload
            options:NSDataBase64DecodingIgnoreUnknownCharacters];

        NSError* jsonError = nil;
        NSDictionary* payloadJson = [NSJSONSerialization JSONObjectWithData:payloadJsonData options:0 error:&jsonError];
        if ( payloadJson )
        {
            if ( payloadJson[@"exp"] )
            {
                NSTimeInterval timestampSeconds = [payloadJson[@"exp"] doubleValue];
                _expirationDate = [NSDate dateWithTimeIntervalSince1970:timestampSeconds];
            }
        }

        _parsedExpirationDate = YES;
    }

    return _expirationDate;
}

The problem is simple. The middle base64 blob, when parsed by NSData -initWithBase64EncodedString is nil - and that's bad.

I've checked the base64 blob and it seems to be valid. My server's returning dummy data for the moment so here's an example blob: eyJlbWFpbCI6ImZvb0BiYXIuYmF6IiwiYWNjb3VudElkIjoiMTIzNDUtNjc4OTAtYmFyLWJheiIsImV4cCI6MTM5MDkxNTAzNywiaWF0IjoxMzkwOTE0MTM3fQ

It decodes to:

{"email":"[e-mail]","accountId":"12345-67890-bar-baz","exp":1390915037,"iat":1390914137}

I tested it here: http://www.base64decode.org

I've used NSData's base64 methods elswhere in my app with success - I don't think I'm doing anything particularly broken here. But I'm all ears! Any ideas?

解决方案

Your Base64 string is not valid. It must be padded with = characters to have a length that is a multiple of 4. In your case: "eyJlbWFp....MTM3fQ==".

With this padding, initWithBase64EncodedString decodes the Base64 string correctly.

这篇关于NSData的将不接受有效的base64 EN codeD字符串的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！