How to implement expiring to the account activation link? - node.js

Question

I am trying to implement expiring to the activation link I send to the user's email when they register a new account.
The link should expire after 24 hours if the user doesn't click on it.
Up until this point I am able to send the link to the user's email upon registration, the link looks like this 'http://localhost:3000/auth/activate/${verificationKey}', everything works smoothly.
But like I said, I want the link to expires after 24 hours and I just don't have any idea of how to do it.
From what I've gathered so far I think one way to do this would be to delete the verificationKey value from my User entity/model after 24 hours, then if the verificationKey value is falsy I need to send another link to the user.
Now my question is, how do I check if a value (in this case user.verification_key) has been generated for over 24 hours?
This is the relevant code to register a new user:
const user = new User();
user.username = username;
user.password = await bcrypt.hash(password, salt);
user.is_verified = false;
user.verification_key = cryptoRandomString({
length: 10,
type: 'url-safe',
});
Some people have suggested to use Redis for this, which I don't know anything about other than it's a in-memory store, and while I'm ok reading more about this tool, I would like to know if there are other ways to do this. I don't know if by installing Redis I would need extra configuration for the server when I host my app, I'd like to avoid that.

Answer 1

Since you already have some database set up, it makes sense to store some verification key and an expiration time for it. You don't need to actually delete that verification key... just need to store when it expires.
Perhaps you have a separate model for RegVerificationKey, with fields key (randomly generated string), expiration (set to a date/time 24 hours after you create it), and userId (the ID of the user this is associated with). Create this key. When you go to activate, just check to see if there is a key associated with the requested user that hasn't expired yet.
Some people have suggested to use Redis for this
No need here, you already have a database you can put data in.
I would like to know if there are other ways to do this
There's an alternative, where you cryptographically sign your URL. Basically, you would store the key and its expiration data in the URL itself, and include some calculated proof that you (the person with the private key) created this URL. When your system receives this URL, it can verify the URL was signed correctly without even having to consult a database. This method can be complicated and probably isn't useful in your case. I'm just mentioning it here as an alternative. Check out JWT for one possible implementation: https://jwt.io/

Answer 2

Recently I was needed to implement this kind of implementation in my web application. So I just followed the below points to achieve it.
1- Create the URL (web link) and append the current date and time along with an encrypted key which you would store in the database as mentioned below.
2- Create a column in the database table (the table where you store any user specific details) to store a randomly generated key which you have encrypted and appended in the URL.
3- When you would receive this URL on server you would check the encrypted date and time in the URL and would decide whether it is still valid depends on your criteria of retaining a link (e.g. 24 hours)
4- Next you would decrypt that key in the URL that you have appended in it at the time of creating it and would match it with what you have stored in the table.
So by implementing above logic you could achieve the desired functionality.
Hope its useful for any one who wants similar type of implementation

Answer 3

I understood that you already found a solution, by storing two fields in the database: one for the key and another one for he expiration timestamp. Everything depends on the use cases and it is definately one way to do it. However I will explain Redis and JWT as a solution in comparison to yours.
Redis is an in-memory datastore (that also allows persistence to disk) as you pointed out and I think the reason why people suggested it is, that you can define an expiration time for a record. Redis will remove that record automatically for you then. Reference: https://redis.io/commands/expire
Redis would take the work off of your shoulders to check if the 24hrs already passed. If you can’t fetch the key anymore, the key probably expired. Another benefit of Redis is, that is super quick compared to your normal database query. But if you only need it for the activation link, which is a one-time-action for the user, the time benefit is negligible. Also you would introduce a new technology just for that use case.
#Brad already suggested using JWT (Json Web Token) instead of implementing your own token solution and I would also suggest that for the following reasons.
A JWT is a self-contained token consisting of three parts: Header, Payload, Signature. The header contains the name of the algorithm that was used to create the token. The paylod contains some standardized fields (e.g. creation date, expiration date, subject the token was issued for like username) and you can also add custom fields. The third part is a signature that ensures that no one changed the payload after it was issued by your token service.
Self-contained means that the token contains everything to validate it, including the expiration timestamp. In your case the expiration time is not part of your token but stored in the database. If you create another microservice that needs to verify your token, that service needs to contact your main service which contains the logic to check the expiration database field.
With JWT the Microservice would only need to know the secret key that was used to sign the token and then you can just import some standard JWT library to verify the token. These libraries validate the signature as well as the expiration timestamp which is an optional field in the payload of the token.
By the way, the payload can be read without knowing the secret key from the signature. So it is even possible to read the payload for example on client side to check the expiration time.
With your solution you have additional database calls, which are potentially slow. For an activation link that is acceptable, but for tokens with recurring use within a short timespan (i.e. API requests that require authentication) additional database calls should be avoided. Also you need to implement token generation and verification yourself, whereas JWT provides standard libraries. This is a benefit when you want to have another Microservice in Java instead of NestJS for example. You can quickly knit them together by using standard libs instead of porting your implemtation or being forced to decide for a centralized token verification service.
One limitation of JWT you have to workaround yourself, is the use case where you want to have a „one time token“. You can only define an expiration date but you can not say that a token can only be used x times. Here you need a centralized service again, which keeps track of how often a token was used (by making use of some datastore) and all other services around need to contact that service.
A good starting point for JWT with NestJS is the official NestJS documentation.