in reply to Crypt::CBC and IO:Socket

You read from the socket until a newline is found, and you assume you have a full (encrypted) message when you do. There's two problems with that:

Start by encrypting the stream rather than each message. 

# Sender
$cipher->start('encrypting');
print $sock $cipher->crypt($_) while <STDIN>;
print $sock $cipher->finish();

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# Receiver
$cipher->start('decrypting');
local $/ = \4096;
process_bytes($cipher->crypt($_)) while <$sock>;
process_bytes($cipher->finish());

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# Interactive receiver
$cipher->start('decrypting');
for (;;) {
   my $rv = sysread($sock, my $buf='', 4096);
   die $! if !defined $rv
   last   if !$rv;
   process_bytes($cipher->crypt($buf));
}
process_bytes($cipher->finish());

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I think $/=4096;<> will wait for 4096 bytes. sysread will return as soon as any bytes are available.

If you want to read a line at a time, you'll need to accumulate and find lines in the plaintext yourself.

Upgrade: Doh! Using sysread is not enough to be truly interactive. You'll need to pad your lines to a multiple of $cipher->blocksize() bytes.

Interactive or not, why not just use IO::Socket::SSL?

Replies are listed 'Best First'.
Re^2: Crypt::CBC and IO:Socket
by WMP (Initiate) on Jul 22, 2009 at 20:42 UTC
    I writed this code: server.pl: 
    sub server {
# my $plaintext = $cipher->decrypt($buf);
# my $in = "SERVER: Text: ".$plaintext;
# my $ciphertext = $cipher->encrypt($in);
# print($new_sock $ciphertext);
my $plaintext = decrypt($buf);
my $in = "SERVER: Text: ".$plaintext;
my $ciphertext = crypt_($in);
}

sub crypt_ {
$cipher->start('encrypting');
print $sock $cipher->crypt($_) while <STDIN>;
print $sock $cipher->finish();
}
sub decrypt {
$cipher->start('decrypting');
local $/ = \4096;
process_bytes($cipher->crypt($_)) while <$sock>;
process_bytes($cipher->finish());
}

    [download]
    client.pl: 
    if ($kid) {
    # parent reads from STDIN, prints to socket
    while (defined($in = <STDIN>)) {
#     my $ciphertext = $cipher->encrypt($in);
#     print $ciphertext;
#    print $sock $ciphertext;
   my $ciphertext = crypt_($in);
    }
    # kill the child process
    kill(TERM => $kid);
} else {
    # child reads from socket, prints to STDOUT
    while (defined($buf = <$sock>)) {
#       my $plaintext = $cipher->decrypt($buf);
#    print $plaintext;
   my $plaintext = decrypt($buf);
   print $plaintext;
    }
    close $sock;
}
sub crypt_ {
$cipher->start('encrypting');
print $sock $cipher->crypt($_) while <STDIN>;
print $sock $cipher->finish();
}
sub decrypt {
$cipher->start('decrypting');
local $/ = \4096;
process_bytes($cipher->crypt($_)) while <$sock>;
process_bytes($cipher->finish());
}

    [download]
    In output from server.pl i have error: 
    wmp@innocence:~/ISS/iss/daemon$ ./server.pl
Undefined subroutine &main::process_bytes called at ./server.pl line 6
+6.
wmp@innocence:~/ISS/iss/daemon$

    [download]
    In client.pl again I must clicks enter. How to i can use IO::Socket::SSL ?
[reply]
[d/l]
[select]

      In output from server.pl i have error:

      You need to provide the sub. Incoming bytes are fed to that sub. What you do in it is up to you.

      In client.pl again I must clicks enter.

      Well yeah, that's what <STDIN> means. You'll need Term::ReadKey to read a key at a time from the keyboard.

[reply]
[d/l]
        What these functions: crypt_ ; decrypt must do? Is this function written properly? Why i'm getting this error: 
        Undefined subroutine &main::process_bytes called at ./server.pl line 6
+6

        [download]
        Line 66: 
        process_bytes($cipher->finish());

        [download]
        And, how can I use IO::Socket::SSL ? There is only http example in manual.
[reply]
[d/l]
[select]

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