Seriously, Inc. employees use a shared 256-bit secret key when exchanging messages.

The actual encryptionscheme is:

 

ciphertext = plaintext XOR extended_key,

where

extended_key = key||key||...||key

,

such that

 

|extended_key| >= |plaintext|

 

(

|x|

 

denotes string length,

x||x

 

–

string concatenation).

Can you help me to decrypt the following HEX cipher text message we have intercepted?

 

676B274A2A5A34312F4D1E167A10205F50565A5020192D40614E53464F14315D5F475D42505E584F141B10405851546536595312205A2E413045544B6E6412502B5C624C2B5435623241594256102752535C5F5C305C284D61514514425C2015515B414052441A167119445B50565B653659531233472C5329545C1562305F11275D6249365C3527635C5F5856433717425C455D64402B416D185F4716402D5444154B5842165C574E5C105D5C4E55376250554636542F5D3C115A572D335E113250234C634129276345455340442A585B1558466A1B

 

Is the given message uniquely decodable? Why?

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