since it is not safe to keep the JWT in local storage because of CSRF or XSS attacks so i am wondering is it possible for example to create a hash function that can hash the JWT and keep the hashed version (useless) in local storage? and we create also a decode function that decode the hashed JWT and return the correct JWT whenever we need to use it.
it seems something manageable to me could there be any possible flaws or issues related to this technique?
That is pretty pointless to hash the JWT.
A better approach is to use the BFF pattern as described in these two resources
alert‘OAuth 2 0’; // The impact of XSS on OAuth 2 0 in SPAs
The BFF Pattern (Backend for Frontend): An Introduction
Related
I need to recompute the hash of private data to proof the integrity of the data. When private data collections are used the private data are stored in SideDBs and the hash of the data on the ledger according to the documentation. Basically the question splits up into two subquestions:
How to access the hash of the private data?
Which method to use to recompute the hash that is saved on the ledger?
Thanks in advance.
I use Hyperledger Fabric v1.4.2 with private data. I followed marbles example.
I expect to be able to calculate the private data hash and verify that it corresponds to the hash saved in the ledger.
to get the SHA256 hash (using Fabric 1.4.x contract API) use:
let pdHashBytes = await ctx.stub.getPrivateDataHash(collectionA, readKey);
let actual_hash = pdHashBytes.toString('hex');
You can calculate the private data written on Ubuntu like shown below.
echo -n "{\"name\":\"Joe\",\"quantity\":999}" |shasum -a 256
and verify they match. So that's the mechanics of using private data method and verify patterns. Now lets add information about salting mechanics, as mentioned elsewhere in this post.
For most uses of private data, you'll most likely use a random salt so the private data cannot be brute force attacked in the permissioned blockchain network (between agreed parties). The salt is passed along in the same transient field as the private data. And (later on), it will need to be included with the private data itself, when recalculating the private data hash. See https://hyperledger-fabric.readthedocs.io/en/release-1.4/private-data-arch.html#protecting-private-data-content
Don't use it, private data is security hole.
It amazes me that nobody had mentioned this before so I guess I better point this out now before more damages are being done.
The logic behind Privated data is simple, it puts data in a local embedded data store and puts a hash of that data on Blockchain.
The issue is that cryptographic hash is not an encryption mechanism, same data hashed by anyone using the same hashing algorithm (which is also very standardized) will always get the same hash! This is exactly what hash functions are designed for, and that’s why we use hash in digital signature to allow anyone to validate signed data.
However, this also means anyone can “decrypt” the data behind the hash by using dictionary attack.
Hashing is cheap, the cost of each hash on a normal laptop CPU core is about 3 microseconds, basically I can create 1 billion candidate hashes within one hour on a single laptop CPU core, and compare them to the hashes on Hyperledger Fabric DLT.
And I am just talking about using a single core on my laptop, not even 50% power of my laptop
Why is it dangerous? Because if an attacker is connected to a Blockchain system, the attacker knows the range of the data being hashed (etc, trade ID, item name, bank name, address, cell phone number), so you can easily create dictionary attack to get the true data behind the hash out.
How about adding salt to each data to be hashed? Well, that’s one thing Hyperledger Fabric didn’t do.
To their defense, Hyperledger didn’t implement salt because it is difficult to pass salts to counter parties. You can’t use DLT to pass salt value because attackers would see it, so you have to create another P2P connection with counter party. If you need to create connection with all the counter parties, what’s the point of using Blockchain in the first place?
It’s just scary that so many people are using this security whole.
is it safe to only use tokens to access/change a user's data in database?
Imagine I get a request with only jwt inside of it and I want to change something for only that user using his token which is stored in database, How do I be certain that no two users have same tokens stored in database? Do I need to get his username ( another data stored in database ) and compare both of them or only token is enough?
Probablytm. The chances of users details hashing to the same string (a collision) are pretty darn small.
The header will be quite common but the payload will vary wildy, depending on the algorithm. The signature is a product of the first two so a collision depends on the payload. This has so info on that (see the accepted answer) https://crypto.stackexchange.com/questions/2558/how-many-rsa-keys-before-a-collision
The simplest answers is that it is possible but it's very very unlikely that this will happen
If I have two JWTs, where their set of claims and headers are the same but the order they are stored in json is different, should they be considered equal?
Clarification:
I am aware that as a user of JWTs you should not need to compare them, but that is not what I am doing.
Say we have some jwt library, and you have some object that represents a JWT in it's decoded form. If we create an encoded JWT from our decoded JWT and then apply it to some function that returns once again the decoded JWT. Do we consider the two decoded JWTs to be equal if the order in which the claims or headers are stored in some collection has changed due to the decoding process?
Thinking more about this, perhaps it is wrong to store the headers and claims in a collection which has some notion of order? Using something like a set makes this problem disappear?
Depends on what you mean by 'different'. If the claims are the same then they are the same in the sense that the information transferred is equal. But if they both have the same signature then at least one will be invalid.
Also you shouldn't need to compare JWT claims at all. If you're storing the token and comparing the token given then you should revisit why you're using JWT over something like session.
JWT is designed to be independent. Because JWT tokens are claims based authentication the validation is done against the signature, not against anything on the server.
I need to store a password's SHA-256 hash in OrientDB REST function - so I can use it to authenticate the user. The incoming call to the REST function will contain the password (over HTTPS) but I want to generate a hash and store that instead of the password itself.
However, OrientDB does not expose any helpers to do this. And straight javascript does not have helpers to do this either... any way I can make this happen?
(one obvious option is to SHA-256 it in the middle tier and pass that to OrientDB but I'd rather keep this in the database tier)
You can use OSecurityManager from Javascript functions like this
return com.orientechnologies.orient.core.security.OSecurityManager.instance().digest2String("password");
I'm making a forget password feature in my web app, problem is I store user's password using:
Hash::make('_their_password_')
Is there any way to re-hash it back or any recommended approach for this?
The point of hashing a password is that it's (supposed to be) an irreversible operation. If your database is compromised, the attacker will gain access to the hashes, but not to the passwords. That way the attacker can't log in with the users' passwords on other sites.
Make a "we'll reset your password" feature instead of a "we'll send you your password" feature.
Note that there are also other best practices you absolutely should be following regarding password hashing, to make sure the "supposed to be" above actually holds, and to further minimize the impact if your site is compromised. Laravel's Hash class seems to already be using the password-appropriate hash function Bcrypt. However, make sure you're using a salt when you're hashing your password.
The Laravel's Hash method cannot be reversed.
One way encryption is the best way to store user passwords, or other sensitive data.
One way means that your data can be converted into an encrypted string, but due to a complex algorithm with painful maths, reversing the process is not possible. This makes storing passwords a doddle! Your customers don't have to worry about you knowing their passwords, but you are still able to compare them (by hashing the password they provide) or change the password if needed.
If you need to reverse, you can use Crypter class.
$secret = Crypter::encrypt('I actually like Hello Kitty');
$decrypted_secret = Crypter::decrypt($secret);
Read more about encryption here http://codehappy.daylerees.com/encryption
If you want to verify the content of password with other value use the following.
return Hash::check($value, auth()->user()->password);