From: Harvie <tomas@mudrunka.cz>
Date: Wed, 3 Nov 2010 03:09:55 +0000 (+0100)
Subject: Added my simple RSA implementation written in PERL for study purposes - it's INSECURE!
X-Git-Url: https://git.harvie.cz/?a=commitdiff_plain;h=8d7c35871a3e8c5a32ff20ec539b456c2da88d5a;p=mirrors%2FPrograms.git

Added my simple RSA implementation written in PERL for study purposes - it's INSECURE!
---

diff --git a/perl/rsa.pl b/perl/rsa.pl
new file mode 100755
index 0000000..c442c6e
--- /dev/null
+++ b/perl/rsa.pl
@@ -0,0 +1,47 @@
+#!/usr/bin/env perl
+#http://en.wikipedia.org/wiki/RSA
+#http://cs.wikipedia.org/wiki/RSA
+use bignum; #We'll need bignum for real messages
+
+sub rsa { #RSA (de)crypt function (message,modulus,exponent)
+	my ($msg,$m,$e) = @_;
+	($msg**$e)%($m);
+}
+
+sub isprime { #Tell if number is prime or not (suboptimal)
+	my ($num) = @_;
+	if($num == 0) { return 1; }
+	$num = abs($num);
+	if($num % 2 == 0) { return 0; }
+	for(my $i = 3; $i <= sqrt($num); $i+=2) {
+		if($num % $i == 0) { return 0; }
+	}
+	return 1;
+}
+
+sub random_prime { #Generate random prime (suboptimal and insecure!)
+	my ($max) = @_;
+	for(my $i = int(rand($max)); $i => 17; $i--) {
+		if(isprime($i)) { return $i; }
+	}
+	return 17;
+}
+
+#Generate key-pair:
+my $strength = 100; #How strong should be the key (insecure!)
+my ($p,$q) = (random_prime($strength),random_prime($strength)); #Generate some big random primes (eg: 61,53)
+my $phi=($p-1)*($q-1); #TODO: implement Euler's totient function for study purposes
+my $n = $p*$q; #modulus (public)
+my $e = random_prime($phi); #e=encrypt exponent (public)
+my $d = Math::BigInt->bmodinv(int($e), $phi); #d=decrypt exponent (PRIVATE!) (TODO: reimplement modinv() for study purposes)
+
+#Example of usage:
+print "\t[[[ Harvie's simple RSA demo ]]]\nfor study & testing purposes only (INSECURE!!!)\n\n";
+print "=== KEYS ===\nPUB: ($n,$e)\nPRV: ($n,$d)\n";
+
+my $msg=1337;
+	print "=== TEST ===\nMSG: $msg\n";
+my $enc=rsa($msg,$n,$e); #encrypt
+	print "ENC: $enc\n";
+my $dec=rsa($enc,$n,$d); #decrypt
+	print "DEC: $dec\nTST: ".$msg.($msg==$dec?"=":"!=").$dec."\n";