It seems that really you are just dealing with big integers. The hex representation is only a detail. Math::BigInt handles the details of representation for you, provides a bitwise 'and' operation, named band:

use Math::BigInt;

my $operand = '0x123456789abcdef0123456789abcdef0';
my $mask    = '0x100000000f00000000000000000000f0';

print Math::BigInt->new($mask)->band($operand)->as_hex(), "\n";
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Math::BigInt also overloads the '&' operator, so you can do things like this:

my $anded = Math::BigInt->new($mask) & $operand;
print $anded->as_hex(), "\n";
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