Re: 2 questions: Prime Numbers and DES

[Adam Back <aba@dcs.ex.ac.uk>]

> Steve Benjamin writes:
> >2.  Is there an implentation of DES in perl?  I didn't see a link to one
> >on the export-a-sig page.  If not perl, is there one for DOS?  I'm
> >looking for a bare bones one, not something with tons of features
> >and a GUI.  A perl or dos version of the unix "des" program would be
> >preferable.
> 
> CPAN (the Comprehensive Perl Archive Network),
> <URL:http://www.perl.com/CPAN/>, is your friend -- use it.  (Look under
> "Authentication, Security and Encryption" -- there are 3 versions of DES
> listed, along with an interface to SSLeay, which includes DES as one of its
> algorithms).

Steve Reid wrote an RSA key generator in perl and dc.  See:

	http://sea-to-sky.net/~sreid/rsagen.txt

I am not sure about the security of the keygeneration algorithm.  Ron
Rivest suggested it as a hack to more easily generate keys on the
coderpunks list I think a year or so back, when Steve was discussing
easier ways to generate valid RSA keys.  But I am not sure if such
keys are hard to factor or not.  Perhaps one should ask Rivest before
using it, you'll have to check the archives for Rivest's comments,
unless you can understand the alogirthm from Steve's code.

Also you asked about DES, here's a compact perl version of DES (not on
my web page, must have forgotten to add it), by John Allen:

#!/bin/perl -s-- DES in perl5
$/=" ";sub u{$_=<DATA>;s/\s//g;map{-33+ord}/./g}$"='';$[=1;@S=map{[u]}1..8;@I=
u;@F=u;@C=(split//,unpack B64,pack H16,$k.0 x16)[u];@D=splice@C,29;@p=u;$_=11 .
2222221 x2;for$l(/./g){map{push@$_,splice@$_,1,$l}\@C,\@D;$K[++$i]="@{[(@C,@D)
[@p]]}"}@E=u;@P=u;%a=map{unpack(B8,chr$_),$_}0..63;while(read STDIN,$b,8){@L=(
split//,unpack B64,$b."\0"x7)[@I];@R=splice@L,33;for$i(1..16){$i=17-$i if$d;@t
=@R[@E];$j=1;$n=0;for(($K[$i]^"@t"|0 x48)=~/.{6}/g){($n<<=4)+=${$S[$j++]}[$a{
"00$_"}+1]};@t=(split//,unpack B32,pack N,$n)[@P];@X=split//,"@L"^"@t"|0 x32;
@L=@R;@R=@X}print pack B64,join'',(@R,@L)[@F]}__END__~printunpacku,'$2F%P:```'
/!%0.("%#/0#,.)"$++''--,&**&!$()%0"-/))#.%'*#",(0&-,*$(/$++!&'!. 0$".)%/('0,#$
)%/*-(!#".+-'!*&,+&!./)(+,"+$%0.%"#&,)'-('-*!$&#/0* +.!(*!/*'$$%0'&+"#.)-&(/,-
%,#0)"."'+%.*!)'0*$)!(,%"0#/-$&,+&/#(- (..)/,$&!''0*!+$"%#()#&-,"-+%/0*+$'0*!!
'-+,"(..)0*"%$&/,&-#()#%/ #/-,%#"-(%+(,.'")&&!$00+.$!*/)*'%,#)"-,(+"./(#).0'*0
-!&*'+$%!&/$ -+"0+%0#*(#-'*)&!'."$.%//!(,&$,)*%/$0#&-#*)&-0$+(,!/%"+("'.!,)'. 
%.,!#,/(0%!*)".+$/-$*&(-&#+0')"'"'%,,..)-"$%(+/(+*0&'!)0!/&#*$#- ."#0).%)'+0$,
("%+-*&$'/,&!!/-*(#(#,"%/"(*%-+/)#.!0'-+*.!0$$&&'), [SKC;3+#]UME=5-%_WOG?7/'aY
QIA91)ZRJB:2*"\TLD<4,$^VNF>6.&`XPH@80( I)Q1Y9aAH(P0X8`@G'O/W7_?F&N.V6^>E%M-U5]
=D$L,T4\<C#K+S3[;B"J*R2Z: ZRJB:2*"[SKC;3+#\TLD<4,$]UME`XPH@80(_WOG?7/'^VNF>6.&
=5-% /2,9"&$=0'6+84-%;)1(<5.#JU@FPX?ITNBQMRHYCVOKSE>A A"#$%&%&'()*)*+,-.-./012
12345656789:9:;<=>=>?@A" 1(56>-=2"08;&3@+#)9/A<$*4.?'7,%:

Adam