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a simple substitution cipher or not?

To discuss DES MD5 El-Gamal RSA PGP and others....
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dion
Member
Posts: 61
Joined: Tue Jul 31, 2007 8:38 am

a simple substitution cipher or not?

Post by dion »

Hi,

just found kind of substitution cipher type (i am quite sure it is substitution), but as i see, substitution cipher like ROT13 use the ascii hex in that range too (if the range is A..Z, then it still using that ascii hex range). but what i found is using another hex range (from 00 ...).

i.e. input :
ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz

output:
1B 18 19 1E 1F 1C 1D 12 13 10 11 16 17 14 15 0A 0B 08 09 0E 0F 0C 0D 02 03 00 7A 3B 38 39 3E 3F 3C 3D 32 33 30 31 36 37 34 35 2A 2B 28 29 2E 2F 2C 2D 22 23 20

i knew its kind of being read back and forth every 2 sequence, kind of big end<>little end thing. anyone know what cipher is this?
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disavowed
Posts: 1290
Joined: Mon Apr 01, 2002 3:00 pm

Post by disavowed »

If that mapping is constant, then yes, it's just a substitution cipher.
dion
Member
Posts: 61
Joined: Tue Jul 31, 2007 8:38 am

Post by dion »

i was doubting it'd be a substitution cipher, because the routine used in reading a large file, which is, afaik, would be slowing things down.
and i was right, it turn out that this is just a simple xor. well, my bad. thanks
sikke
Junior Member
Posts: 10
Joined: Sat Feb 27, 2010 10:03 am

Post by sikke »

Looks indeed like xor with 'Z' = 0x5A.
This is a substitution cipher, indeed, but of a simple kind.
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