1.1.05. Most of you got it right. Some of you thought 'shifting with key 12' was to shift the alphabet backward, which in effect encripts the message with key 14 (26-12, see 1.1.15). For this problem, 1.3.04 (otp) and 1.4.04 (affine cipher), you can verify your result with a simple Perl script like the following.
#!/usr/bin/perl
@input_text=split(//,$ARGV[0]);
$key=$ARGV[1];
foreach (@input_text) {
if($_ eq " "){
print " ";
}else {
print chr((ord($_)-ord('a')+$key)%26+ord('a'));
}
}
print "\n";
This script is not quite "Perlish", you Perl hackers may come up with a more succint script using pack/unpack.