NAME

       rskeygen - generate private key pairs for TI graphing calculators

SYNOPSIS

       rskeygen [ --secure ] [ --ti ] [ --length nbytes ]

DESCRIPTION

       rskeygen  generates application and OS signing keys for the Texas Instruments TI-73, TI-83
       Plus, TI-84 Plus, TI-89, and TI-92 Plus graphing calculators.  These keys consist  of  two
       prime  numbers  p  and  q  as well as their product n.  Current calculator models impose a
       limit of 512 bits (64 bytes) on the size of n, so p and q are  generally  about  256  bits
       each.   As  of  this  writing  this  means factoring n is beyond the reach of most people,
       though this will undoubtedly change in the future.

       The keys generated by rskeygen are not very useful at the moment, because in order for  an
       application or OS to be accepted by the calculator, the key used to sign it must itself be
       signed using the calculator's own (possibly unique) private key, which is  only  known  to
       TI.   Nevertheless,  rskeygen  is  provided  in  the  hope that it can be useful, both for
       testing and for devising new signature schemes based on TI's.

   OPTIONS
       --secure
              Attempt to generate a ``secure'' key using the system's entropy  pool,  /dev/random
              (see   random(4).)   The  actual  security  is  thus  dependent  on  your  system's
              implementation of /dev/random.

              Without --secure, the keys are generated based on the current time and process  ID,
              which is not secure in the slightest.

       --ti   Generate  keys  which  are  palatable  to TI's official app signing programs.  This
              forces p to be congruent to 3 and q to 7 modulo 8.  This option  is  not  necessary
              when  using  rabbitsign(1),  nor  is  it  necessary  for the calculator to validate
              signatures properly.

       --length nbytes
              Specify the length in bytes of the modulus n; p and q are  each  calculated  to  be
              approximately  half  this  length.   This should not be greater than 64 for current
              calculators, and must be less than 256 in any event due to a limitation of the  key
              file format.

SEE ALSO

       rabbitsign(1), packxxk(1)

AUTHOR

       Benjamin Moody <floppusmaximus@users.sf.net>