41 lines
2.0 KiB
Markdown
41 lines
2.0 KiB
Markdown
# Secure "Remember Me"
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This library implements the best practices for implementing a secure
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"Remember Me" functionality on web sites. Login information and unique secure
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tokens are stored in a cookie. If the user visits the site, the login information
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from the cookie is compared to information stored on the server. If the tokens
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match, the user is logged in. A user can have login cookies on several
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computers/browsers.
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This library is heavily inspired by Barry Jaspan's article
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"[Improved Persistent Login Cookie Best Practice][1]". The library protects
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against the following attack scenarios:
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- The computer of a user is stolen or compromised, enabling the attacker to log
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in with the existing "Remember Me" cookie. The user knows this has happened.
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The user can remotely invalidate all login cookies.
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- An attacker has obtained the "Remember Me" cookie and has logged in with it.
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The user does not know this. The next time he tries to log in with the cookie
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that was stolen, he gets a warning and all login cookies are invalidated.
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- An attacker has obtained the database of login tokens from the server. The
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stored tokens are hashed so he can't use them without computational effort
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(rainbow tables or brute force).
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## Installation
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composer require birke/rememberme
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## Usage example
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See the `example` directory for an example.
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## Improving security
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The generated tokens are pseudo-random and the storage classes use the SHA1 algorithm
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to hash them. If you need better security than that, overwrite the
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`Authenticator::generateToken` method to generate a truly random token. If you are
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using PHP >=5.5 you can use the "[password_hash][2]" and "[password_verify][3]" functions.
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On lower PHP versions you could use the [userland implementations][4] of these functions.
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[1]: http://jaspan.com/improved%5Fpersistent%5Flogin%5Fcookie%5Fbest%5Fpractice
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[2]: http://www.php.net/manual/en/function.password-hash.php
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[3]: http://www.php.net/manual/en/function.password-verify.php
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[4]: https://github.com/ircmaxell/password_compat
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