Data commit

Task/RSA-code/Perl/rsa-code.pl

@@ -0,0 +1,63 @@
+use bigint;
+
+$n = 9516311845790656153499716760847001433441357;
+$e = 65537;
+$d = 5617843187844953170308463622230283376298685;
+
+package Message {
+    my @alphabet;
+    push @alphabet, $_ for 'A' .. 'Z', ' ';
+    my $rad = +@alphabet;
+    $code{$alphabet[$_]} = $_ for 0..$rad-1;
+
+    sub encode {
+        my($t) = @_;
+        my $cnt = my $sum = 0;
+        for (split '', reverse $t) {
+            $sum += $code{$_} * $rad**$cnt;
+            $cnt++;
+        }
+        $sum;
+    }
+
+    sub decode {
+        my($n) = @_;
+        my(@i);
+        while () {
+            push @i, $n % $rad;
+            last if  $n < $rad;
+            $n = int $n / $rad;
+        }
+        reverse join '', @alphabet[@i];
+    }
+
+    sub expmod {
+    my($a, $b, $n) = @_;
+    my $c = 1;
+    do {
+        ($c *= $a) %= $n if $b % 2;
+        ($a *= $a) %= $n;
+    } while ($b = int $b/2);
+    $c;
+}
+
+}
+
+my $secret_message = "ROSETTA CODE";
+
+$numeric_message  = Message::encode $secret_message;
+$numeric_cipher   = Message::expmod $numeric_message, $e, $n;
+$text_cipher      = Message::decode $numeric_cipher;
+$numeric_cipher2  = Message::encode $text_cipher;
+$numeric_message2 = Message::expmod $numeric_cipher2, $d, $n;
+$secret_message2  = Message::decode $numeric_message2;
+
+print <<"EOT";
+Secret message is $secret_message
+Secret message in integer form is $numeric_message
+After exponentiation with public exponent we get: $numeric_cipher
+This turns into the string $text_cipher
+If we re-encode it in integer form we get $numeric_cipher2
+After exponentiation with SECRET exponent we get: $numeric_message2
+This turns into the string $secret_message2
+EOT