Question

I need help with this home work:

Given the Caesar cipher output wzgp xp ezytrse, what is the plaintext message? Start with the first possible key (a>b), then the second possible key (a>c), the third possible key (a>d), and so on until you reach a plaintext that is easily recognizable. You may stop there! Hint:

Answer 1

Ceaser cipher: it is simple substitution cipher where each letter of text is replaced by a letter with some fixed position.

for example shift of 2 means A becomes C, B becomes D so on.

Here encoded Ceaser cipher is given. we have to decode it.

D(x)= (x-n)mod 26

Here n is a shift

we are using brute force technique to guess plain text.

Cipher text = wzgp xp ezytrse

shift	Plain Text
+1	VYFOWODYXSQRD
+2	UXENVNCXWRPQC
+3	TWDMUMBWVQOPB
+4	SVCLTLAVUPNOA
+5	RUBKSKZUTOMNZ
+6	QTAJRJYTSNLMY
+7	PSZIQIXSRMKLX
+8	ORYHPHWRQLJKW
+9	NQXGOGVQPKIJV
+10	MPWFNFUPOJHIU
+11	LOVEMETONIGHT

so when the shift is 11 we got plain text

Plain text: love me tonight

shift: 11

Cipher text: wzgp xp ezytrse