\"QUESTION 5 CIPHER George owns a company that produces mobile phones to end use
ID: 3702590 • Letter: #
Question
"QUESTION 5 CIPHER George owns a company that produces mobile phones to end users. George's company must keep up with other competitors therefore during a company meeting George announced that he will be making changes to their new upcoming mobile device. George's company follows a strict confidentiality policy when it comes to the exchange of information. To prevent the leakage of information during transmission George also informed his employees during the meeting that he will be sending them instructions encrypted under Caesar cipher followed by another substitution where the key is 234. Employees received the following cipher text. NTJWKHXK AMK WWUJJYZTX MWKXZKUHE What is the plain text?"Explanation / Answer
Answer- INCREASE THE PROCESSOR FREQUENCY
1) using the given key 234, decrypting the given cipher text into intermediary cipher text by left shifting the letters, you get
LQFUHDVH WKH SURFHVVRU IUHTXHQFB( left shifted first letter of given ciphertext by 2, second letter by 3, third letter by 4, fourth letter by 2, fifth by 3, sixth by 4, so on till end)
2 ) doing frequency analysis of intermediary cipher text from step 1 I got the following frequencies,
monogram, digrams, trigrams were- B=1, D=1, F=3, H=6, I=1, K=1, L=1, Q=2, R=2, S=1, T=1, U=3, V=3, W=1, X=1
VV=1, SU=1, FH=1, TX=1, LQ=1, HQ=1, IU=1, HT=1, HV=1, FU=1, XH=1, DV=1, VH=1, UH=2, WK=1, RF=1, QF=2, HD=1, VR=1, FB=1, KH=1, UR=1
LQF=1, UHT=1, XHQ=1, QFU=1, TXH=1, URF=1, HVV=1, QFB=1, HTX=1, UHD=1, SUR=1, VVR=1, WKH=1, RFH=1, FHV=1, DVH=1, FUH=1, HDV=1, HQF=1, IUH=1
3) I observed H=6, and assigned to one of the most frequently used english alphabets(e,t ,a)
4) I assumed H as E for a trial which meant the most probable key used in the first round of encyption is right shift of 3 alphabet places.
5)Hence I left shifted each letter by 3 places the text from step 1.
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