4 ms·

I wonder if Facebook stores it's password in clear-text, since you can login with either 'Password' or 'password', does it hash the first character and the rest

I wonder if Facebook stores it's password in clear-text, since you can login with either 'Password' or 'password', does it hash the first character and the rest into 2 different hashes? If not, we have a our passwords in readable form in their database that have huge privacy and security issues.

ohwp 14y ago
Or they just make everything lower- or uppercase before checking it against the encrypted version.
- rmc 14y ago
  Almost certainly not, since this would reduce the entropy of their passwords, making brute forcing easier.
switz 14y ago
They hash it once and save it to the database. When logging in, they generate three hashes (if I remember correctly) and compare it to the hash in the database. If any match, it logs you in. Edit: Here's a post on the matter http://www.zdnet.com/blog/facebook/facebook-passwords-are-not-case-sensitive-update/3612 http://www.zdnet.com/blog/facebook/facebook-passwords-are-no...
pidge 14y ago
It's more likely that they coerce to lowercase the the first letter of the password you put in and then store/compare the hash of that resulting plaintext. They could even transparently upgrade passwords created before they started doing this by using the plaintext from the next time you login successfully to regenerate the hash.
- buddydvd 14y ago
  Lowercasing the first character--by itself alone--does not address inverted case scenario (e.g. "PaSsWoRd" and "pAsSwOrD" evaluate to "paSsWoRd" and "pAsSwOrD" respectively). One way to resolve that issue is to create two versions of the password (one with normal casing and one with inverted casing, but both with the first character lowercased), sort them, and pick the first result. ["pAsSwOrD", "PaSsWoRd", "PAsSwOrD"].map(function canonicalize(pwd) { function invert(str) { return (str == str.toUpperCase() ? str.toLowerCase() : str.toUpperCase()); } var head = pwd.substring(0, 1).toLowerCase(); var tail = pwd.substring(1); var vers = [head + tail, head + tail.split("").map(invert).join("")]; return vers.sort()[0]; }); Which gives the following result: ["pAsSwOrD", "pAsSwOrD", "pAsSwOrD"] The three different variations get canonicalized into one version. With it, you can just store one hash instead of three.
akx 14y ago
Facebook stores three hashes of your password (let's say it's "pAssword"): * "pAssword" - the password as it is * "PaSSWORD" - the password, case inverted, in case you have caps lock on * "PAssword" - the password with its first letter capitalized, for those with mobile devices that insist on Capitalizing Everything.
- cnicolaou 14y ago
  Isn't that supposed to increase the chances of guessing the password? Unless there's a constraint on the number of attempts to guess the password, which I think there is.
  - shrughes 14y ago
    By a factor of three, which is nothing.
- bungle 14y ago
  I don't think they store three hashes, but just try to validate password with three hashes. Something inline this: https://github.com/bungle/web.php/blob/master/password.php#L50 https://github.com/bungle/web.php/blob/master/password.php#L...
  - sehe 14y ago
    What's the password doing on their server? Also, why is there no salt in the comparison. It calls a naked crypt, that whole ... interesting ... hash() function is sitting there unused. I have serious doubts whether this code actually serves the user's interest - despite trying to be cute and helpful
    - bungle 14y ago
      You seemingly don't understand a bit about it. And you seemingly doesn't understand how crypt works. Let me educate you: 1. When user registers, his password is hashed with that hash-function, and that hash is stored in a database (it uses random salt). 2. When user tries to access the site, a password is hashed against the hash stored in a database, and it should return same hash if matched (this is how crypt works!). 3. In non strict mode we try also two different passwords to match the hashes (just like Facebook does). Code example: 1. $hash = \password\hash('user entered password'); // store it to db 2. retrieve hash from db, and check it: $valid = \password\check('user entered password', $hash, false); 3. // Now these passwords are valid: 'user entered password' // == correct form 'User entered password' // == Mobile browser capitalizing first char 'USER ENTERED PASSWORD' // == CAPS LOCK on And one line example: $valid = \password\check('user entered password', \password\hash('user entered password'), false); // == true

ohwp 14y ago

Or they just make everything lower- or uppercase before checking it against the encrypted version.

rmc 14y ago
Almost certainly not, since this would reduce the entropy of their passwords, making brute forcing easier.

switz 14y ago

They hash it once and save it to the database. When logging in, they generate three hashes (if I remember correctly) and compare it to the hash in the database. If any match, it logs you in. Edit: Here's a post on the matter http://www.zdnet.com/blog/facebook/facebook-passwords-are-not-case-sensitive-update/3612 http://www.zdnet.com/blog/facebook/facebook-passwords-are-no...

pidge 14y ago

It's more likely that they coerce to lowercase the the first letter of the password you put in and then store/compare the hash of that resulting plaintext. They could even transparently upgrade passwords created before they started doing this by using the plaintext from the next time you login successfully to regenerate the hash.

buddydvd 14y ago
Lowercasing the first character--by itself alone--does not address inverted case scenario (e.g. "PaSsWoRd" and "pAsSwOrD" evaluate to "paSsWoRd" and "pAsSwOrD" respectively). One way to resolve that issue is to create two versions of the password (one with normal casing and one with inverted casing, but both with the first character lowercased), sort them, and pick the first result. ["pAsSwOrD", "PaSsWoRd", "PAsSwOrD"].map(function canonicalize(pwd) { function invert(str) { return (str == str.toUpperCase() ? str.toLowerCase() : str.toUpperCase()); } var head = pwd.substring(0, 1).toLowerCase(); var tail = pwd.substring(1); var vers = [head + tail, head + tail.split("").map(invert).join("")]; return vers.sort()[0]; }); Which gives the following result: ["pAsSwOrD", "pAsSwOrD", "pAsSwOrD"] The three different variations get canonicalized into one version. With it, you can just store one hash instead of three.

akx 14y ago

Facebook stores three hashes of your password (let's say it's "pAssword"): * "pAssword" - the password as it is * "PaSSWORD" - the password, case inverted, in case you have caps lock on * "PAssword" - the password with its first letter capitalized, for those with mobile devices that insist on Capitalizing Everything.

cnicolaou 14y ago
Isn't that supposed to increase the chances of guessing the password? Unless there's a constraint on the number of attempts to guess the password, which I think there is.
- shrughes 14y ago
  By a factor of three, which is nothing.
bungle 14y ago
I don't think they store three hashes, but just try to validate password with three hashes. Something inline this: https://github.com/bungle/web.php/blob/master/password.php#L50 https://github.com/bungle/web.php/blob/master/password.php#L...
- sehe 14y ago
  What's the password doing on their server? Also, why is there no salt in the comparison. It calls a naked crypt, that whole ... interesting ... hash() function is sitting there unused. I have serious doubts whether this code actually serves the user's interest - despite trying to be cute and helpful
  - bungle 14y ago
    You seemingly don't understand a bit about it. And you seemingly doesn't understand how crypt works. Let me educate you: 1. When user registers, his password is hashed with that hash-function, and that hash is stored in a database (it uses random salt). 2. When user tries to access the site, a password is hashed against the hash stored in a database, and it should return same hash if matched (this is how crypt works!). 3. In non strict mode we try also two different passwords to match the hashes (just like Facebook does). Code example: 1. $hash = \password\hash('user entered password'); // store it to db 2. retrieve hash from db, and check it: $valid = \password\check('user entered password', $hash, false); 3. // Now these passwords are valid: 'user entered password' // == correct form 'User entered password' // == Mobile browser capitalizing first char 'USER ENTERED PASSWORD' // == CAPS LOCK on And one line example: $valid = \password\check('user entered password', \password\hash('user entered password'), false); // == true