in reply to Understanding Obfuscation

Character-based XOR works on the binary representation of the characters. 
'd' = 100 (base 10) = 01100100
'A' =  65 (base 10) = 01000001
'd' ^ 'A'           = 00100101 = 37 (base 10) = '%'

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Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

In Section Seekers of Perl Wisdom