Think back to the last time you looked at an unfamiliar block of code. Did you immediately understand what it was doing? If not, you’re not alone – many software developers, including myself, find it challenging to grasp unfamiliar code quickly…
It’s unclear, but quite likely that the type has changed here. Even in a duck typed language this is hard to manage and often leads to bugs.
Even without a type change, you shouldn’t reuse an object member like this. Dramatically better to have password and hashed_password so that they never get mixed up. If you don’t want the raw password available after this point, zero it out or delete it.
All of these style considerations apply 4x as strongly when it’s a piece of code that’s important to the security of your service, which obviously hashing passwords is.
I appreciate the security concerns, but I wouldn’t consider overriding the password property with the hashed password to be wrong. Raw passwords are typically only needed in three places: user creation, login, and password reset. I’d argue that having both password and hashedPassword properties in the user object may actually lead to confusion, since user objects are normally used in hundreds of places throughout the codebase. I think, when applicable, we should consider balancing security with code maintainability by avoiding redundancy and potential confusion.
When is the hashed password needed other than user creation, login or password resets? Once you have verified the user you should not need it at all. If anything storing it on the user at all is likely a bad idea. Really you have two states here - the unauthed user which has their login details, and an authed user which has required info about the user but not their password, hashed or not.
Personally I would construct the user object from the request after doing auth - that way you know that any user object is already authed and it never needs to store the password or hash at all.
Perhaps I was unclear. What I meant to say is that, whenever possible, we shouldn’t have multiple versions of a field, especially when there is no corresponding plaintext password field in the database, as is the case here.
And they were arguing the same - just renaming the property rather than reusing it. You should only have one not both but naming them differently can make it clear which one you have.
But here I am arguing to not have either on the user object at all. They are only needed at the start of a request and should never be needed after that point. So no point in attaching them to a user object - just verify the username and password and pass around user object after that without either the password or hash. Not everything needs to be added to a object.
I agree. The field shouldn’t have been called ‘password’ in the first place, but rather ‘plaintextPassword’ or similar. That makes the code much more readable, if at a glance I know if I’m dealing with the hash or the plaintext version.
In addition to the excellent points made by steventhedev and koper:
Just this one line of code alone is wrong.
I appreciate the security concerns, but I wouldn’t consider overriding the password property with the hashed password to be wrong. Raw passwords are typically only needed in three places: user creation, login, and password reset. I’d argue that having both password and hashedPassword properties in the user object may actually lead to confusion, since user objects are normally used in hundreds of places throughout the codebase. I think, when applicable, we should consider balancing security with code maintainability by avoiding redundancy and potential confusion.
When is the hashed password needed other than user creation, login or password resets? Once you have verified the user you should not need it at all. If anything storing it on the user at all is likely a bad idea. Really you have two states here - the unauthed user which has their login details, and an authed user which has required info about the user but not their password, hashed or not.
Personally I would construct the user object from the request after doing auth - that way you know that any user object is already authed and it never needs to store the password or hash at all.
Perhaps I was unclear. What I meant to say is that, whenever possible, we shouldn’t have multiple versions of a field, especially when there is no corresponding plaintext password field in the database, as is the case here.
And they were arguing the same - just renaming the property rather than reusing it. You should only have one not both but naming them differently can make it clear which one you have.
But here I am arguing to not have either on the user object at all. They are only needed at the start of a request and should never be needed after that point. So no point in attaching them to a user object - just verify the username and password and pass around user object after that without either the password or hash. Not everything needs to be added to a object.
I absolutely agree. An even better structure wouldn’t have a raw password field on the user object at all.
I agree. The field shouldn’t have been called ‘password’ in the first place, but rather ‘plaintextPassword’ or similar. That makes the code much more readable, if at a glance I know if I’m dealing with the hash or the plaintext version.