On 6/20/07, oryann9 <[EMAIL PROTECTED]> wrote:
snip
> > my $plaintext = do { local $/ = undef; <> };
> > my $pad = "X" x length $plaintext;
> >
> > my $encryptedtext = $plaintext ^ $pad;
snip
I like it to, but dont understand how it is
encrypting.
Will you kindly expalin?
$plaintext is the contents of the file(s) passed in on the commandline
(or stdin if none are passed in).
$pad is the character X repeated until there are as many Xs as
characters in $plaintext
$encryptedtext is the result of xor'ing $plaintext with pad.
xor has the following truth table
A B R
0 0 0
0 1 1
1 0 1
1 1 0
so if I have 01101100 and I xor it with 01110001 I get 00011101. This
is the "encrypted value". If I xor the result 00011101 with the key
01110001 I get the original value back.
01101100 plaintext
01110001 key
00011101 "encrypted"
00011101 "encrypted"
01110001 key
01101100 plaintext
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