We frequently need to send entity ids to the client side.

How could we protect this data (especially ids)?

Even if we encrypt using same key every time, it can be identified by analysis.

For example, if I encrypt id "1" to let's say "ae!" (using any algorithm), that same id can be used later on as well.

So should we use session id as key to send data to client side (this will validate data only up-to session is active)? Or could we randomly append a string to id "1", encrypt it and then send to client side (this also can be sent any next time)?

Or is there any other way?

What is best practice for this type of security take care?

I am using .Net MVC C#. But I think question is irrelevant of platform.

Let's take an example.

In the following link id is given in datasource, which is plain text, so any person with technical knowledge can modify it (using developer console of browser).

So IMHO it should be encrypted, to make it unchangeable (because the changed value is not acceptable due to encryption).


  • 1
    I fail to understand what your problem is. But it seems to be about protecting data transferred between client and server. If this is really your problem why not simply use HTTPS? May 26, 2018 at 19:44
  • I want to make ids unclear to any one (let's say user with developer mind) which can be get using developer console. id should not be open to browser. May 26, 2018 at 19:47
  • 1
    If you want have the key to be available within the browser using Javascript but not accessible using developer tools then this is impossible. If you just want to hide the server-side meaning of the key use a random key and associate it server-side with the relevant data using a database or similar. Also note that the 'ids' tag stands for intrusion detection system which is probably not what you mean (I've removed it). May 26, 2018 at 19:50
  • key in browser is fine. just it should not be plain text. May 26, 2018 at 19:55
  • Why do you need to keep the id private, are there other security holes you wish to work around
    – jrtapsell
    May 26, 2018 at 21:19

1 Answer 1


You can use an hash of the ids. For example, in pseudo-code,

sha2(entry_id || delimiter || user_id)

will do what you want:

  • all the users will see the same content on the same id,
  • not the users, not even potentially cooperating different users will be able to identify the entities by their hashes.
  • however, all the user will see the same entity behind the same hash.

The disadvantage of the method is that you need a backend storage for the per-user hash keys - the users will refer the entities only by their hash, and not even you will be able to decode out the entity from them.

You may get increased security by binding the hash to the session instead of the user:

sha2(entry_id || delimiter || session_id)

This will increase security (not even the user will be able to identify the entities between their sessions), and you will need to store the hashes only until session timeout. However, the user will be unable to produce a client-side entity storage (what may be also an advantage, too).

  • This seems to be what i wanted. just want ur suggestion. session_id is available at client side cookies. so should i generate key and store in cookies instead? May 30, 2018 at 14:48
  • @HardikViradiya Store it in the session, not in cookies... cookies are visible for the client browsers, the session data is not.
    – peterh
    May 30, 2018 at 15:13
  • I was editing it. but message was showing like "cannot edit in 5 mins" when tried to edit comment. one more thing. it is not feasible to store hash value to some store. :( May 30, 2018 at 15:31
  • @HardikViradiya And why? You need only a single Map<String, int> (I don't know the correct syntax in .Net but probably some similar), i.e. an integer array indexed with the hashed entity ids. If you have a Map<String, int> cica, then cica["fce2c0de...."] will give you back the integer entity_id belonging to the cica entities. But the client browser won't see this id, he will see only the hash.
    – peterh
    May 30, 2018 at 15:40
  • @HardikViradiya If you want a f*g fast app, you could use some bigint type instead of a String map. For example, if the hash function generates 128bit integers, then instead of using their hexa representation as string, you could use a 128bit binary value (it has probably the "BigInt" or "LongLongInt" or similar name).
    – peterh
    May 30, 2018 at 15:42

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