src/mcookie/mcookie.1

   1 .\" mcookie.1 --
   2 .\" Public Domain 1995 Rickard E. Faith (faith@cs.unc.edu)
   3 .TH MCOOKIE 1 "25 September 1995" "" "Linux Programmer's Manual"
   4 .SH NAME
   5 mcookie \- generate magic cookies for xauth
   6 .SH SYNOPSIS
   7 .BI "mcookie [\-v] [\-f " filename " ]"
   8 .SH DESCRIPTION
   9 .B mcookie
  10 generates a 128-bit random hexadecimal number for use with the X authority
  11 system.  Typical usage:
  12 .RS
  13 xauth add :0 . `mcookie`
  14 .RE
  15 .PP
  16 The "random" number generated is actually the output of the MD5 message
  17 digest fed with various piece of random information: the current time, the
  18 process id, the parent process id, the contents of an input file (if
  19 .B \-f
  20 is specified), and several bytes of information from the first of the
  21 following devices which is present:
  22 .IR /dev/random ,
  23 .IR /dev/urandom ,
  24 files in
  25 .IR /proc ,
  26 .IR /dev/audio .
  27 .SH BUGS
  28 The entropy in the generated 128-bit is probably quite small (and,
  29 therefore, vulnerable to attack) unless a non-pseudorandom number generator
  30 is used (e.g.,
  31 .I /dev/random
  32 under Linux).
  33 .PP
  34 It is assumed that none of the devices opened will block.
  35 .SH FILES
  36 .I /dev/random
  37 .br
  38 .I /dev/urandom
  39 .br
  40 .I /dev/audio
  41 .br
  42 .I /proc/stat
  43 .br
  44 .I /proc/loadavg
  45 .SH "SEE ALSO"
  46 .BR X (1),
  47 .BR xauth (1),
  48 .BR md5sum (1)