Can someone explain to me what the "cost" option is?
Increasing cost by 1 doubles the time needed to create a hash.
A simple benchmark with results: http://pastebin.com/NiqKEAVm
Creating and Verifying Hashes in PHP 5.5
21–30 of 44 posts
Re: Creating and Verifying Hashes in PHP 5.5
#22This is a great addition to PHP. Before, most new devs would either skip hashing passwords altogether or use `md5()` or `sha1()`. So you'd end up with databases with passwords in plaintext or easily cracked. Bcrypt frameworks for PHP were too confusing for beginners. If you were lucky you were using a framework that took care of hashing and salting passwords and if you were extremely lucky you had bcrypt available on…
>There do exist experienced PHP devs who would do password storage the right way but PHP up until now neither made it easy nor encourage these practices as they relate to passwords. I'm happy to be one of them! The app I'm currently building uses this bcrypt library, and I can only highly recommend it: http://www.openwall.com/phpass/
phpass is actually one of the libraries I was talking about. When I first encountered it I was really intimidated. The usage didn't seem that bad to figure out but trying to comb through it's page to find installation instructions was tough. It didn't seem clear about whether this was a module like imagemagick that needed to be installed or if it was a drop-in library you could just use within any project.
Looking back now it seems obvious but back then it just too overwhelming. With PHP there's this 'just get it done' attitude and futzing around with phpass wasn't something I could let myself do back then.
Of course I now regret it. I ended up using a different encryption library for password storage on my app. It isn't md5 but I know it could and should be stronger. So now I'm in a situation where I'm rewriting the codebase in a different language entirely and the cherry on top is that I need to migrate all my user's passwords and even some data from the original method to bcrypt, which I'm now using. It seems simple in theory but I have a feeling this is going to cause some headaches. However, its totally necessary and especially for the type of application I'm working on which puts a big focus on privacy and security.
Re: Creating and Verifying Hashes in PHP 5.5
#23Earlier quoted context omitted.
There's also PHPass from OpenWall: http://www.openwall.com/phpass/
If you use PHPass, remember to check your hashes to make sure they're actually hashed with bcrypt. PHPass falls back to a less secure algorithm if bcrypt is not available in your PHP version. Most of the CMS's that claim to use PHPass actually use the "portable" option, which is based on MD5, because they want to remain compatible with PHP versions lower than 5.3 (the first version that is guaranteed to support bcryp…
> Most of the CMS's that claim to use PHPass actually use the "portable" option
This is true for WordPress, which uses PHPass. You have to replace `wp_hash_password` to get WP to use bcrypt: http://wptip.me/wordpress-bcrypt
Re: Creating and Verifying Hashes in PHP 5.5
#24> 'salt' => password_hash("MySalt",PASSWORD_BCRYPT)] This is really, really dumb and pointless. In fact it makes absolutely no sense, it tells password_hash to use a bcrypted "MySalt" as a salt. Not only is there no reason to explicitly provide a salt unless you already have bcrypted passwords in a non-standard format, (in which case you'd pass the existing $salt directly, you wouldn't bcrypt it) this is an inane way…
Adding that salt is optional. I'm pretty sure the author just added it to the post so people know it exists. I don't think it's dumb and pointless at all, really. Generally you wouldn't generate a salt yourself if you're using bcrypt however I'm sure there would be cases where it would be needed or even preferred for some reason. I would advocate for flexibility and education rather than rigidity and simplicity. That…
> Adding that salt is optional. I'm pretty sure the author just added it to the post so people know it exists.
I have nothing against adding a salt manually to show how it works, I have things against adding stupid salts.
> I don't think it's dumb and pointless at all, really.
You're missing the criticism. The problem isn't the ability to inject a salt (it is useful e.g. when the (cost, salt, hash) triple is in a format other than MCF), it is the way the salt is obtained.
Re: Creating and Verifying Hashes in PHP 5.5
#25Just noting if you're new to this you don't have to add a salt, by default password_hash with bcrypt will add a random one to each password.
How does that work? Don't you need the original salt to verify the hash?
Re: Creating and Verifying Hashes in PHP 5.5
#26> 'salt' => password_hash("MySalt",PASSWORD_BCRYPT)] This is really, really dumb and pointless. In fact it makes absolutely no sense, it tells password_hash to use a bcrypted "MySalt" as a salt. Not only is there no reason to explicitly provide a salt unless you already have bcrypted passwords in a non-standard format, (in which case you'd pass the existing $salt directly, you wouldn't bcrypt it) this is an inane way…
Why don't you generate your salt by hand?
Because there's very little point in doing so since bcrypt will automatically generate one for you.
A use case for manually injecting the salt is when your KDF result isn't stored in Modular Crypt Format, and thus you can't just pass it to `password_verify`.
In that case, you get your stored cost and salt, explicitly inject them into `password_hash` and use a constant-time string comparison (which I'm not sure PHP provides, so there's a potential security hole here) instead of `password_verify`.
Re: Creating and Verifying Hashes in PHP 5.5
#27This is a great addition to PHP. Before, most new devs would either skip hashing passwords altogether or use `md5()` or `sha1()`. So you'd end up with databases with passwords in plaintext or easily cracked. Bcrypt frameworks for PHP were too confusing for beginners. If you were lucky you were using a framework that took care of hashing and salting passwords and if you were extremely lucky you had bcrypt available on…
I am on md5 on one of my projects but it's salted alright. I want to change it. I reckon there is no way to migrate other than resetting every user password.
Re: Creating and Verifying Hashes in PHP 5.5
#28This is a great addition to PHP. Before, most new devs would either skip hashing passwords altogether or use `md5()` or `sha1()`. So you'd end up with databases with passwords in plaintext or easily cracked. Bcrypt frameworks for PHP were too confusing for beginners. If you were lucky you were using a framework that took care of hashing and salting passwords and if you were extremely lucky you had bcrypt available on…
I am on md5 on one of my projects but it's salted alright. I want to change it. I reckon there is no way to migrate other than resetting every user password.
Actually, you can migrate slowly.
Create a second password column on your database to store your new hash. When a user logs in check if the new column is blank. If it is check that they entered the password correctly by verifying against your MD5 hash. If it is correct rehash their plain text and store it in the new column.
If the new column isn't blank, then the have already logged in and you have the new hash, so verify against the new hash. As everyone logs into your website, you'll have a new set of, more secure, hashes. For those that are inactive you can either delete them, assign a random password and email them, or let their MD5 password hash sit there forever.
Re: Creating and Verifying Hashes in PHP 5.5
#29This is a great addition to PHP. Before, most new devs would either skip hashing passwords altogether or use `md5()` or `sha1()`. So you'd end up with databases with passwords in plaintext or easily cracked. Bcrypt frameworks for PHP were too confusing for beginners. If you were lucky you were using a framework that took care of hashing and salting passwords and if you were extremely lucky you had bcrypt available on…
I am on md5 on one of my projects but it's salted alright. I want to change it. I reckon there is no way to migrate other than resetting every user password.
You could add a second password column to your users. Then if that column is empty, authenticate against the old password. If it passes, hash the password (just supplied by the user) with bcrypt and store it in the new column.
Over time, active users get their password upgraded.
Then after a longer time, just reset the passwords of the users who never logged in since you started migrating.
Re: Creating and Verifying Hashes in PHP 5.5
#30Earlier quoted context omitted.
I am on md5 on one of my projects but it's salted alright. I want to change it. I reckon there is no way to migrate other than resetting every user password.
Actually, you can migrate slowly. Create a second password column on your database to store your new hash. When a user logs in check if the new column is blank. If it is check that they entered the password correctly by verifying against your MD5 hash. If it is correct rehash their plain text and store it in the new column. If the new column isn't blank, then the have already logged in and you have the new hash, so v…
Don't forget to delete the value in the md5 column, otherwise the whole exercise is for naught.