There are probably a zillion ways to do this. The simplest to me seems like a s///e substitution:

$x =~ s/(.)/ord $1/egs;
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If you ever want to get the data back though, this is a bad encoding. For instance do you decode "64" as chr(6).chr(4) or just chr(64)? Maybe you should pad out the ASCII values to 3 digits (though probably won't work with some wide unicode characters)

$x =~ s/(.)/sprintf "%03d", ord $1/egs;
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Then to get the characters back:

$x =~ s/(\d{3})/chr $1/g;
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