By about 1300 CE, Arabic cryptographers had determined that you can decipher messages in which one letter has been replaced by another letter, number, or symbol by exploiting statistical characteristics of the underlying language. Here are some especially useful patterns in English.

*E*is by far the most common letter – representing about 1/8th of normal text.- If you list the alphabet from most to least commonly used, it divides into four groups.
- The highest frequency group includes:
*e*,*t*,*a*,*o*,*n*,*i*,*r*,*s*, and*h*. - The middle frequency group includes:
*d*,*l*,*u*,*c*, and*m*. - Less common are
*p*,*f*,*y*,*w*,*g*,*b*, and*v*. - The lowest frequency group includes:
*j*,*k*,*q*,*x*, and*z*. *E*associates most widely with other letters: appearing before or after virtually all of them, in different circumstances.- Among combinations of
*a*,*i*, and*o**io*is the most common combination.*Ia*is the second most common.*Ae*is rarest. - 80% of the time,
*n*is preceded by a vowel. - 90% of the time,
*h*appears before vowels. *R*tends to appear with vowels;*s*tends to appear with consonants.- The most common repeated letters are
*ss*,*ee*,*tt*,*ff*,*ll*,*mm*and*oo*.

Naturally, there are thousands more such patterns. Even understanding a few can help in deciphering messages that have had a basic substitution cipher applied.

Here’s one to try out:

LKCLHQBCKDRCPQQBDKAPZULSQUCDK

AZRDTDGPCOTZKQDPQBZQDQZHHLOIP

XLSVDQBZAOCZQICZGLHQDJCQLOCZI

QBDKAPQBZQDKQCOCPQXLSDKXLSOPM

ZOCQDJCSKHLOQSKZQCGXLQQZVZDPO

CGZQDTCGXMLLOGXMOLTDICIHLOVDQ

BRZHCPQLLJZKXLHQBCJRGLPCNSDQC

CZOGXDKQBCCTCKDKA

One hint is that cipher alphabets are not always entirely random. The tools on this page are useful for cracking monoalphabetic substitution ciphers.

{ 9 comments… read them below or add one }

Here is a much easier to solve ciphetext from Simon Singh’s website.

What a difference spaces make…

Crushing by elephant

In your puzzle, I am betting C is ‘e’ and Q is ‘t.’

If Q is ‘t’, QQZVZ might be ‘Ottawa.’

LQQZVZ, rather

oKeoHtBeKDRePttBDKAPaUoStUeDK

AaRDTDGPeOTaKtDPtBatDtaHHoOIP

XoSwDtBaAOeatIeaGoHtDJetoOeaI

tBDKAPtBatDKteOePtXoSDKXoSOPM

aOetDJeSKHoOtSKateGXottawaDPO

eGatDTeGXMooOGXMOoTDIeIHoOwDt

BRaHePtooJaKXoHtBeJRGoPeNSDte

eaOGXDKtBeeTeKDKA

‘tBe’ occurs three times, so B may be ‘h.’

oKeoHtheKDRePtthDKAPaUoStUeDK

AaRDTDGPeOTaKtDPthatDtaHHoOIP

XoSwDthaAOeatIeaGoHtDJetoOeaI

thDKAPthatDKteOePtXoSDKXoSOPM

aOetDJeSKHoOtSKateGXottawaDPO

eGatDTeGXMooOGXMOoTDIeIHoOwDt

hRaHePtooJaKXoHtheJRGoPeNSDte

eaOGXDKtheeTeKDKA

abcdefghijklmnopqrstuvwxyz

Z—C–B——L—-Q–V—

I am betting the cipher alphabet is in the form:

abcdefghijklmnopqrstuvwxyz

WORDABCEFGHIJKLMNPQSTUVWYZ