75N79T77B7HE8C7OFJBE9DCWJQRBKXDM6PMV1TJOW51X9LSKJ0

Input----> binary ----> dec(1)
Key------> MD5(base16) ----> dec(2)
dec(1)*dec(2) = dec(3)

dec(4)= dec(3) padded with itself to be the same length(or longer) as dec(3)

dec(3) XOR dec(4) ----> base36 ----> Output
//reverse________________________________________________________________________________________
Output ----> base36 ----->dec(5)
dec(5) XOR dec(4) = dec(3)

dec(3)/dec(2) = dec(1)

dec(1) ---> binary ----> UTF-8 ----> Input

ttTtt

Example:

input = "6u8b"
key = "key"

input ---> 00110110011101010011100001100010 --> 913651810
key------> MD5 = 3c6e0b8a9c15224a8228b9a98ca1531d --> 80325066489831061459460196859901989661

key*input = 80325066489831061459460196859901989661*913651810 = 73389142386804495896657050484005769276373936410(this is dec3)
73389142386804495896657050484005769276373936410 XOR 8032506648983106145946019685990198966180325066489831061459460196859901989661 (MD5 to the same(longer in this case) length as dec3) = 8032506648983106145946019685922970759228882849748582617896490145877473655303 <-- in base36 = output=

FXMRE4PS5UE9WOH7AK7DHTO8O8F5T1Z3H2MNF3OPGXRZRWHZB
reverse_________________________________________________________________________________________

FXMRE4PS5UE9WOH7AK7DHTO8O8F5T1Z3H2MNF3OPGXRZRWHZB in base36 =
8032506648983106145946019685922970759228882849748582617896490145877473655303

key in MD5 = 3c6e0b8a9c15224a8228b9a98ca1531d
MD5 in decimal is 80325066489831061459460196859901989661

73389142386804495896657050484005769276373936410
XOR 8032506648983106145946019685990198966180325066489831061459460196859901989661
(MD5 to the same(longer in this case) length as dec3)
= 73389142386804495896657050484005769276373936410

73389142386804495896657050484005769276373936410 / MD5 =
73389142386804495896657050484005769276373936410 / 80325066489831061459460196859901989661 = 913651810

913651810 in base(2) = 110110011101010011100001100010

binary string leftpadded with "0" until that (binary string length)mod8 = 0
padded 00110110011101010011100001100010 --> ASCII = "6u8b"