TUCoPS :: Crypto :: lesson2.txt

Breaking Cue:Cat Encryption for Complete Fucking Retards

   breaking That advanced (for a 2nd grader) encryption (if you can call it that) 
                                    of the cue:cat
                               for complete fucking retards

Ok we should all have a cue cat by now, if not we should be heading out the door right now
to get one for FREE from radio shack then come back and read this text. The encryption of
the cue:cat is a BASE 64 cypher. it's quite simple. first well start with some input and 
what it comes out as

input  >>  195
output >>  CNP2 

Well to decrypt this lets look at the ratio of output to input, yeah that is odd.
so we can automaticly figure all the bits are not used in the output, so heres how it
works. first heres the decodeing table.. 

0  >> abcdefghijklmnop << 15
16 >> qrstuvwxyzABCDEF << 31
48 >> WXYZ0123456789** << 63

ok that said, lets break down each output byte acording to the table's decimal value

Byte    >    C        N        P        2
Decimal >    28       39       41       54
Binary  > 00011100 00100111 00101001 00110110

now lets do some math to decide how many bits you need from each byte.
(i figured i would put the math here in the file, so i didn't loose the majority of ya)

 b * i / o

b = number of bits per byte, this is 8
i = number of input bytes, this is 3
o = number of output bytes, this is 4


so we need 6 bits from each byte, looking at the pateren we see the 2 most significant bits
are always 0, se lets strip those leaving us with.

Striped  > 011100 100111 101001 110110

ok well we need 3 bytes so lets regroup the bits.

Regroup  > 01110010 01111010 01110110
Decimal  >    114      122      118
Byte     >    r        z        v

well this is not the input, what do we have to do to get the output from that.  XOR!!

Regroup  > 01110010 01111010 01110110
Xor with > 01000011 01000011 01000011
Xored    > 00110001 00111001 00110101
Decimal  >    49       57       53
Byte     >    1        9        5

ok well there ya go thats how the decypher works for the cue:cat

and if you dont understand it now, then you may need to locate a copy of the 
  "for still born babies" version of this text..

copyright(c) 2001 by HeadTrip.
e-mail headtrip@ureach.com

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