对于我正在从事的一个新的node.js项目,我正在考虑从基于cookie的会话方法(我的意思是,将id存储到用户浏览器中包含用户会话的键值存储中)切换到使用JSON Web Tokens (jwt)的基于令牌的会话方法(没有键值存储)。

这个项目是一个利用socket的游戏。IO——在一个会话(web和socket.io)中有多个通信通道的情况下,有一个基于令牌的会话会很有用。

如何使用jwt方法从服务器提供令牌/会话失效?

我还想了解使用这种范例应该注意哪些常见的(或不常见的)陷阱/攻击。例如,如果这种模式容易受到与基于会话存储/cookie的方法相同/不同类型的攻击。

所以,假设我有以下内容(改编自this和this):

会话存储登录:

app.get('/login', function(request, response) {
    var user = {username: request.body.username, password: request.body.password };
    // Validate somehow
    validate(user, function(isValid, profile) {
        // Create session token
        var token= createSessionToken();

        // Add to a key-value database
        KeyValueStore.add({token: {userid: profile.id, expiresInMinutes: 60}});

        // The client should save this session token in a cookie
        response.json({sessionToken: token});
    });
}

口令登录:

var jwt = require('jsonwebtoken');
app.get('/login', function(request, response) {
    var user = {username: request.body.username, password: request.body.password };
    // Validate somehow
    validate(user, function(isValid, profile) {
        var token = jwt.sign(profile, 'My Super Secret', {expiresInMinutes: 60});
        response.json({token: token});
    });
}

--

会话存储方法的注销(或失效)需要更新KeyValueStore 使用指定的令牌创建数据库。

在基于令牌的方法中似乎不存在这样的机制,因为令牌本身将包含通常存在于键值存储中的信息。


当前回答

在经过一些研究后,我的观点如下。 在登出期间,确保发生了以下事情…

清除客户端存储/会话

分别在登录或注销发生时更新用户表的上一次登录日期-时间和注销日期-时间。因此登录日期时间应该总是大于注销(或者如果当前状态是登录且尚未注销,则将注销日期保持为空)

这远比保持额外的黑名单表和定期清洗简单。多设备支持需要额外的表来保存loggedIn、注销日期和一些额外的详细信息,如操作系统或客户端详细信息。

其他回答

如果您希望能够撤销用户令牌,您可以跟踪DB上所有发出的令牌,并检查它们在类似会话的表上是否有效(存在)。 缺点是每次请求都要访问DB。

我还没有尝试过,但我建议使用以下方法来允许令牌撤销,同时将DB命中保持在最小值-

为了降低数据库检查率,根据某种确定性关联将所有已发行的JWT令牌分成X组(例如,按用户id的第一个数字分为10组)。

每个JWT令牌将保存组id和令牌创建时创建的时间戳。例如,{"group_id": 1, "timestamp": 1551861473716}

服务器将在内存中保存所有组id,每个组都有一个时间戳,该时间戳指示属于该组的用户的最后一次注销事件是什么时候。 例如,{"group1": 1551861473714, "group2": 1551861487293,…}

使用带有较旧组时间戳的JWT令牌的请求将被检查是否有效(DB hit),如果有效,将发出一个带有新时间戳的新JWT令牌供客户端将来使用。 如果令牌的组时间戳较新,则相信JWT (No DB hit)。

So -

We only validate a JWT token using the DB if the token has an old group timestamp, while future requests won't get validated until someone in the user's group will log-out. We use groups to limit the number of timestamp changes (say there's a user logging in and out like there's no tomorrow - will only affect limited number of users instead of everyone) We limit the number of groups to limit the amount of timestamps held in memory Invalidating a token is a breeze - just remove it from the session table and generate a new timestamp for the user's group.

在经过一些研究后,我的观点如下。 在登出期间,确保发生了以下事情…

清除客户端存储/会话

分别在登录或注销发生时更新用户表的上一次登录日期-时间和注销日期-时间。因此登录日期时间应该总是大于注销(或者如果当前状态是登录且尚未注销,则将注销日期保持为空)

这远比保持额外的黑名单表和定期清洗简单。多设备支持需要额外的表来保存loggedIn、注销日期和一些额外的详细信息,如操作系统或客户端详细信息。

没有使用jwt的刷新…

我想到了两种袭击的场景。一个是关于登录凭证的泄露。另一个是对JWT的盗窃。

For compromised login credentials, when a new login happens, normally send the user an email notification. So, if the customer doesn't consent to being the one who logged in, they should be advised to do a reset of credentials, which should save to database/cache the date-time the password was last set (and set this too when user sets password during initial registration). Whenever a user action is being authorized, the date-time a user changed their password should be fetched from database/cache and compared to the date-time a given JWT was generated, and forbid the action for JWTs that were generated before the said date-time of credentials reset, hence essentially rendering such JWTs useless. That means save the date-time of generation of a JWT as a claim in the JWT itself. In ASP.NET Core, a policy/requirement can be used to do do this comparison, and on failure, the client is forbidden. This consequently logs out the user on the backend, globally, whenever a reset of credentials is done.

For actual theft of JWT... A theft of JWT is not easy to detect but a JWT that expires easily solves this. But what can be done to stop the attacker before the JWT expires? It is with an actual global logout. It is similar to what was described above for credentials reset. For this, normally save on database/cache the date-time a user initiated a global logout, and on authorizing a user action, get it and compare it to the date-time of generation of a given JWT too, and forbid the action for JWTs that were generated before the said date-time of global logout, hence essentially rendering such JWTs useless. This can be done using a policy/requirement in ASP.NET Core, as previously described.

现在,你如何发现JWT被盗?目前我对此的回答是,偶尔提醒用户全局注销并重新登录,因为这肯定会让攻击者注销。

If you are using axios or a similar promise-based http request lib you can simply destroy token on the front-end inside the .then() part. It will be launched in the response .then() part after user executes this function (result code from the server endpoint must be ok, 200). After user clicks this route while searching for data, if database field user_enabled is false it will trigger destroying token and user will immediately be logged-off and stopped from accessing protected routes/pages. We don't have to await for token to expire while user is permanently logged on.

function searchForData() {   // front-end js function, user searches for the data
    // protected route, token that is sent along http request for verification
    var validToken = 'Bearer ' + whereYouStoredToken; // token stored in the browser 

    // route will trigger destroying token when user clicks and executes this func
    axios.post('/my-data', {headers: {'Authorization': validToken}})
     .then((response) => {
   // If Admin set user_enabled in the db as false, we destroy token in the browser localStorage
       if (response.data.user_enabled === false) {  // user_enabled is field in the db
           window.localStorage.clear();  // we destroy token and other credentials
       }  
    });
     .catch((e) => {
       console.log(e);
    });
}

每个用户字符串唯一,全局字符串散列在一起作为JWT的秘密部分,允许单独和全局令牌无效。最大的灵活性,代价是在请求身份验证期间数据库查找/读取。也很容易缓存,因为它们很少改变。

这里有一个例子:

HEADER:ALGORITHM & TOKEN TYPE

{
  "alg": "HS256",
  "typ": "JWT"
}
PAYLOAD:DATA

{
  "sub": "1234567890",
  "some": "data",
  "iat": 1516239022
}
VERIFY SIGNATURE

HMACSHA256(
  base64UrlEncode(header) + "." +
  base64UrlEncode(payload), 
  HMACSHA256('perUserString'+'globalString')
)

where HMACSHA256 is your local crypto sha256
  nodejs 
    import sha256 from 'crypto-js/sha256';
    sha256(message);

例如,用法参见https://jwt.io(不确定他们是否处理动态256位秘密)