The quest for the most diminutive munitions program
There have been a number of revisions of the RSA in perl hack as people have contributed ways to shorten it. Here are the interesting ones, the smallest and most recent first:
Current best, perl5 and dc
Currently there is no explanation for this one, but is similar to the 3 line version in the way that it works, see below.
print pack"C*",split/\D+/,`echo "16iII*o\U@{$/=$z;[(pop,pop,unpack"H*",<>
)]}\EsMsKsN0[lN*1lK[d2%Sa2/d0<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<J]dsJxp"|dc`Previous best, works with perl4 and dc
There is an explanation (http://www.dcs.ex.ac.uk/~aba/rsa/story2.html) of how this works in
detail.
#!/bin/perl -sp0777i<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<j]dsj
$/=unpack('H*',$_);$_=`echo 16dio\U$k"SK$/SM$n\EsN0p[lN*1
lK[d2%Sa2/d0$^Ixp"|dc`;s/\W//g;$_=pack('H*',/((..)*)$/)Prior to that
(this one is the one on many T-shirts (http://www.obscura.com/~shirt/), and the one in the tattoo):
#!/bin/perl -s-- -export-a-crypto-system-sig -RSA-3-lines-PERL
$m=unpack(H.$w,$m."\0"x$w),$_=`echo "16do$w 2+4Oi0$d*-^1[d2%Sa
2/d0<X+d*La1=z\U$n%0]SX$k"[$m*]\EszlXx++p|dc`,s/^.|\W//g,print
pack('H*',$_)while read(STDIN,$m,($w=2*$d-1+length$n&~1)/2)Original version which started the trend
9 March 1995 (http://www.dcs.ex.ac.uk/~aba/rsa/org-post.html) The original version which
started this trend of perl crypto hacks.
An explanation (http://www.dcs.ex.ac.uk/~aba/rsa/hal-reply.html) of how this one works was
posted to the cypherpunks list by Hal Finney shortly after I posted it.
#!/usr/local/bin/perl -- export-a-crypto-system sig, RSA in 5 lines of PERL:
($s,$k,$n)=@ARGV;$w=length$n;$k="0$k"if length($k)&1;$n="0$n",$w++if$w&1;die
"$0 -d|-e key mod <in >out\n"if$s!~/^-[de]$/||$#ARGV<2;$v=$w;$s=~/d/?$v-=2:
$w-=2;$_=unpack('B*',pack('H*',$k));s/^0*//g;s/0/d*ln%/g;s/1/d*ln%lm*ln%/g;
$c="1${_}p";while(read(STDIN,$m,$w/2)){$m=unpack("H$w",$m);chop($a=
`echo 16o16i\U$m\Esm\U$n\Esn$c|dc`);print pack('H*','0'x($v-length$a).$a);}Pure perl version
Pure perl (http://www.dcs.ex.ac.uk/~aba/rsa/pureperl.html) version by Clifford Adams in 5
lines of perl.
#!/usr/local/bin/perl -s
do 'bigint.pl';($_,$n)=@ARGV;s/^.(..)*$/0$&/;($k=unpack('B*',pack('H*',$_)))=~
s/^0*//;$x=0;$z=$n=~s/./$x=&badd(&bmul($x,16),hex$&)/ge;while(read(STDIN,$_,$w
=((2*$d-1+$z)&~1)/2)){$r=1;$_=substr($_."\0"x$w,$c=0,$w);s/.|\n/$c=&badd(&bmul
($c,256),ord$&)/ge;$_=$k;s/./$r=&bmod(&bmul($r,$r),$x),$&?$r=&bmod(&bmul($r,$c
),$x):0,""/ge;($r,$t)=&bdiv($r,256),$_=pack(C,$t).$_ while$w--+1-2*$d;print}Comments, html bugs to me (Adam Back (http://www.dcs.ex.ac.uk/~aba/)) at <aba@dcs.ex.ac.uk>
