Req #61394 [Opn]: Provide secure drop-in replacement for mt_rand()
Edit report at https://bugs.php.net/bug.php?id=61394&edit=1
ID: 61394
Updated by: pajoye@php.net
Reported by: tstarling@php.net
Summary: Provide secure drop-in replacement for mt_rand()
Status: Open
Type: Feature/Change Request
Package: Unknown/Other Function
PHP Version: 5.4SVN-2012-03-15 (SVN)
Block user comment: N
Private report: N
New Comment:
Hi Tim,
The needs are definitively here.
Some comments/questions for the record here:
Which platforms do not have openssl_random_pseudo_bytes?
mcrypt_generate_iv relies on external library as it is enabled only if mcrypt is
available, sadly. However one could emulate it or enforce good configuration by
checking and using the session.entropy_file which should be set to urandom or
equivalent.
Also it is important to say that URANDOM is not crytpo safe. So depending on the
usages, it is not thought to be uses for security sensitive purposes. However it
could be enough for one time password and related usages.
Previous Comments:
------------------------------------------------------------------------
[2012-03-15 02:00:05] tstarling@php.net
Description:
------------
mt_rand() is insecure, but people keep using it for security-sensitive purposes anyway, because:
* The interface is more familiar than functions that return binary strings, like
openssl_random_pseudo_bytes() and mcrypt_create_iv(). Legacy code uses rand() or mt_rand().
* openssl_random_pseudo_bytes() and mcrypt_generate_iv() are not available on every platform, so
mt_rand() is a simple alternative for a developer of distributed software.
I propose adding a function to ext/standard which has the same parameters and return value type as
mt_rand(), but uses a secure random source. In particular, I think the random number generation
method used by mcrypt_generate_iv(..., MCRYPT_DEV_URANDOM) is most appropriate. It is fast and works
on virtually every platform supported by PHP without external library dependencies.
Like mcrypt_generate_iv(), the new function could raise a warning and return false if /dev/urandom
cannot be opened. The application can then decide based on its security policies whether it wishes
to fall back to mt_rand() or abort the transaction.
The function could be called os_rand(), like Python's os.urandom(), or secure_rand() or
rand_s(), like in the Windows CRT security extension.
------------------------------------------------------------------------
--
Edit this bug report at https://bugs.php.net/bug.php?id=61394&edit=1
Thread (4 messages)