Information Technology Reference
In-Depth Information
Table 10.1 Message Decodings with a Caesar Cipher
Shift by
Alphabet Coded By
Possible Decoding of Message
0
ABCDEFGHIJKLMNOPQRSTUVWXYZ
Igkygx iovnkxy gxk kgye zu ixgiq
1
BCDEFGHIJKLMNOPQRSTUVWXYZA
Hfjxfw hnvmjwx fwj jfxd yt hwfhp
2
CDEFGHIJKLMNOPQRSTUVWXYZAB
Geiwev gmtlivw evi iewc xs gvego
3
DEFGHIJKLMNOPQRSTUVWXYZABC
Fdhvdu flskhuv duh hdvb wr fudfn
4
EFGHIJKLMNOPQRSTUVWXYZABCD
Ecguct ekrjgtu ctg gcua vq etcem
5
FGHIJKLMNOPQRSTUVWXYZABCDE
Dbftbs djqifst bsf fbtz up dsbdl
6
GHIJKLMNOPQRSTUVWXYZABCDEF
Caesar ciphers are easy to crack
7
HIJKLMNOPQRSTUVWXYZABCDEFG
Bzdrzq bhogdqr zqd dzrx sn bqzbj
8
IJKLMNOPQRSTUVWXYZABCDEFGH
Aycqyp agnfcpq ypc cyqw rm apyai
9
JKLMNOPQRSTUVWXYZABCDEFGHI
Zxbpxo zfmebop xob bxpv ql zoxzh
10
KLMNOPQRSTUVWXYZABCDEFGHIJ
Ywaown yeldano wna awou pk ynwyg
11
LMNOPQRSTUVWXYZABCDEFGHIJK
Xvznvm xdkczmn vmz zvnt oj xmvxf
12
MNOPQRSTUVWXYZABCDEFGHIJKL
Wuymul wcjbylm uly yums ni wluwe
13
NOPQRSTUVWXYZABCDEFGHIJKLM
Vtxltk vbiaxkl tkx xtlr mh vktvd
14
OPQRSTUVWXYZABCDEFGHIJKLMN
Uswksj uahzwjk sjw wskq lg ujsuc
15
PQRSTUVWXYZABCDEFGHIJKLMNO
Trvjri tzgyvij riv vrjp kf tirtb
16
QRSTUVWXYZABCDEFGHIJKLMNOP
Squiqh syfxuhi qhu uqio je shqsa
17
RSTUVWXYZABCDEFGHIJKLMNOPQ
Rpthpg rxewtgh pgt tphn id rgprz
18
STUVWXYZABCDEFGHIJKLMNOPQR
Qosgof qwdvsfg ofs sogm hc qfoqy
19
TUVWXYZABCDEFGHIJKLMNOPQRS
Pnrfne pvcuref ner rnfl gb penpx
20
UVWXYZABCDEFGHIJKLMNOPQRST
Omqemd oubtqde mdq qmek fa odmow
21
VWXYZABCDEFGHIJKLMNOPQRSTU
Nlpdlc ntaspcd lcp pldj ez nclnv
22
WXYZABCDEFGHIJKLMNOPQRSTUV
Mkockb mszrobc kbo okci dy mbkmu
23
XYZABCDEFGHIJKLMNOPQRSTUVW
Ljnbja lryqnab jan njbh cx lajlt
24
YZABCDEFGHIJKLMNOPQRSTUVWX
Kimaiz kqxpmza izm miag bw kziks
25
ZABCDEFGHIJKLMNOPQRSTUVWXY
Jhlzhy jpwolyz hyl lhzf av jyhjr
letter, with T second, and so forth.
2
Thus, another approach to
breaking a code (given enough text to study) is to count the number
of times each coded letter occurs. The chances are quite good that
the letter appearing most frequently will be an E or T, for example.
Approaches to Improve the Caesar Cipher: With these basic
weaknesses in the Caesar Cipher, improvements could be made in
several ways. First, during encoding, instead of simply replacing a
letter by the third (or
n
th) letter after it, each letter could be
matched with a random letter of a new madeup alphabet. This
2 Sinkov, op. cit. presents more frequency count information on p. 16.
