Fred is right. If it's a simple substitution of some sort and the text
is English, it won't be too hard to crack.
My wife Julie is reading a fictional book in which cracking codes is a
big part. (Can't remember the title.) I taught her a little about how
monoalphabetic codes worked, and kidded with her to let me know when
she wanted to try cracking one. She said "Ready when you are!", so I
created a 21 character key and threw the remaining characters at the
end. (There's a big hint for you!) I then encrypted the final three
paragraphs and came up with this cipher text:
"YKIX FSD DUID A BUIGG TK DUK AFBDXLJKFD SY YLDLXK JABHUAKY. JV PSXE
AB FKIXGV HSJCGKDK. FKADUKX VSLXB FSX IFV JIF'B NKIDU AB FKKNKN DS
HSFBLJJIDK DUK BKXAKB SY JV TKAFO, IFN IHHSJCGABU DUID PUAHU JLBD TK
NSFK; TLD AD XKWLAXKB JV SPF. NS FSD DUAFE DUID A BUIGG TK BGSP DS
CKXYSXJ DUAB BIHXAYAHK. A BUIGG WLAD VSLX MKBBKG SF DUK AHKXIYD PUAHU
TXSLOUD JK DUADUKX, IFN BUIGG BKKE DUK JSBD FSXDUKXF KQDXKJADV SY DUK
OGSTK; A BUIGG HSGGKHD JV YLFKXIG CAGK IFN HSFBLJK DS IBUKB DUAB
JABKXITGK YXIJK, DUID ADB XKJIAFB JIV IYYSXN FS GAOUD DS IFV HLXASLB
IFN LFUIGGSPKN PXKDHU PUS PSLGN HXKIDK BLHU IFSDUKX IB A UIMK TKKF. A
BUIGG NAK. A BUIGG FS GSFOKX YKKG DUK IOSFAKB PUAHU FSP HSFBLJK JK, SX
TK DUK CXKV SY YKKGAFOB LFBIDABYAKN, VKD LFWLKFHUKN. UK AB NKIN PUS
HIGGKN JK AFDS TKAFO; IFN PUKF A BUIGG TK FS JSXK DUK MKXV XKJKJTXIFHK
SY LB TSDU PAGG BCKKNAGV MIFABU. A BUIGG FS GSFOKX BKK DUK BLF SX
BDIXB, SX YKKG DUK PAFNB CGIV SF JV HUKKEB. GAOUD, YKKGAFO, IFN BKFBK
PAGG CIBB IPIV; IFN AF DUAB HSFNADASF JLBD A YAFN JV UICCAFKBB. BSJK
VKIXB IOS, PUKF DUK AJIOKB PUAHU DUAB PSXGN IYYSXNB YAXBD SCKFKN LCSF
JK, PUKF A YKGD DUK HUKKXAFO PIXJDU SY BLJJKX, IFN UKIXN DUK XLBDGAFO
SY DUK GKIMKB IFN DUK PIXTGAFO SY DUK TAXNB, IFN DUKBK PKXK IGG DS JK,
A BUSLGN UIMK PKCD DS NAK; FSP AD AB JV SFGV HSFBSGIDASF. CSGGLDKN TV
HXAJKB, IFN DSXF TV DUK TADDKXKBD XKJSXBK, PUKXK HIF A YAFN XKBD TLD
AF NKIDU?
"YIXKPKGG! A GKIMK VSL, IFN AF VSL DUK GIBD SY ULJIF EAFN PUSJ DUKBK
KVKB PAGG KMKX TKUSGN. YIXKPKGG, YXIFEKFBDKAF! AY DUSL PKXD VKD IGAMK,
IFN VKD HUKXABUKN I NKBAXK SY XKMKFOK IOIAFBD JK, AD PSLGN TK TKDDKX
BIDAIDKN AF JV GAYK DUIF AF JV NKBDXLHDASF. TLD AD PIB FSD BS; DUSL
NANBD BKKE JV KQDAFHDASF DUID A JAOUD FSD HILBK OXKIDKX PXKDHUKNFKBB;
IFN AY VKD, AF BSJK JSNK LFEFSPF DS JK, DUSL UIBD FSD HKIBKN DS DUAFE
IFN YKKG, DUSL PSLGNBD FSD NKBAXK IOIAFBD JK I MKFOKIFHK OXKIDKX DUIF
DUID PUAHU A YKKG. TGIBDKN IB DUSL PKXD, JV IOSFV PIB BDAGG BLCKXASX
DS DUAFK; YSX DUK TADDKX BDAFO SY XKJSXBK PAGG FSD HKIBK DS XIFEGK AF
JV PSLFNB LFDAG NKIDU BUIGG HGSBK DUKJ YSX KMKX.
"TLD BSSF," UK HXAKN, PADU BIN IFN BSGKJF KFDULBAIBJ, "A BUIGG NAK,
IFN PUID A FSP YKKG TK FS GSFOKX YKGD. BSSF DUKBK TLXFAFO JABKXAKB
PAGG TK KQDAFHD. A BUIGG IBHKFN JV YLFKXIG CAGK DXALJCUIFDGV, IFN
KQLGD AF DUK IOSFV SY DUK DSXDLXAFO YGIJKB. DUK GAOUD SY DUID
HSFYGIOXIDASF PAGG YINK IPIV; JV IBUKB PAGG TK BPKCD AFDS DUK BKI TV
DUK PAFNB. JV BCAXAD PAGG BGKKC AF CKIHK; SX AY AD DUAFEB, AD PAGG FSD
BLXKGV DUAFE DULB. YIXKPKGG."
UK BCXLFO YXSJ DUK HITAF-PAFNSP, IB UK BIAN DUAB, LCSF DUK AHK-XIYD
PUAHU GIV HGSBK DS DUK MKBBKG. UK PIB BSSF TSXFK IPIV TV DUK PIMKB IFN
GSBD AF NIXEFKBB IFN NABDIFHK.
You know this going in - it's a monoalphabetic cipher with a 21
character key. That means you know more than she did going in. Folks,
she broke the code by hand with very little frequency analysis!
Everything she did to break this code she did in her head. That means
what frequency analysis she did was something like "I see that
character more than any other, so it's probably an E."
I'd think that most people with a little knowledge of the English
language could figure this out fairly easily. (There's only two words
that are single letters - A and I, and A probably isn't a above. E is
the most common letter in the English language. etc)
Take that same text above and throw in nulls of some sort and that
gets a lot harder to break until you figure out what the nulls are. (I
was going to use Z, which I think is an unused character, as a null
but I went easy on her for this one.)
If anyone's bored enough to crack the cipher text above, let me know.
Once it's back to plain text, tell me where the quote is from.
Likewise if anyone's so frustrated in trying to crack it that they're
about to flip out, email me and I'll dig the key up. :)
Boy that was a long winded way of saying null characters make ciphers
harder to decrypt!
As for the original poster talking about ways to encrypt something,
why not use DES? Basic DES can be cracked by a home computer in less
than a day - probably quicker with the high powered PC's we have
today. It's be challenging, yet fun for your classmates.
- Dave
--
Dave Bush <hockeystatman@gmail.com>
There are two seasons in my world - Hockey and Construction
