MCOOKIE(1) Linux Programmer's Manual MCOOKIE(1)
mcookie - generate magic cookies for xauth
mcookie [-v] [-f filename ]
mcookie generates a 128-bit random hexadecimal number for use with the
X authority system. Typical usage:
xauth add :0 . `mcookie`
The "random" number generated is actually the output of the MD5 message
digest fed with various piece of random information: the current time,
the process id, the parent process id, the contents of an input file
(if -f is specified), and several bytes of information from the first
of the following devices which is present: /dev/random, /dev/urandom,
files in /proc, /dev/audio.
The entropy in the generated 128-bit is probably quite small (and,
therefore, vulnerable to attack) unless a non-pseudorandom number gen-
erator is used (e.g., /dev/random under Linux).
It is assumed that none of the devices opened will block.
X(1), xauth(1), md5sum(1)
25 September 1995 MCOOKIE(1)