Solving Singh's Substitution Cipher
Many of us enjoy playing with encryption algorithms. Simon Singh, before a book promotion trip to Greece, published a "substitution cipher with a twist". I would consider solving a substitution cipher aimed at the general public unfair, but the "twist" made me curious.
The cryptogram's text reads as follows:
GPJDB, SB MDJTP, DOJ DQWP PO HTDOG UPDMJTOHW, D MDSST, DO DJNTMDQ OPGPMTPKW ZPM UTW QTOYW GP NDWPOMB, D GMTP PZ IDMJTODQW, D GMTP, GPP, PZ TOWTHOTZTIDOG VPQTGTITDOW (SPKHUG DOJ VDTJ ZPM SB D MTIU DOJ IPMMKVGDOHQP-IDODJTDO SDOYTOH IPMVPMDGTPO) TOZPMN KW DQQ PZ UPF PKM IPKOGMB OPF MTWYW JBTOH PZ WGDMXDGTPO.D MKNPKM, GUDGW NB TOTGTDQ GUPKHUG DW T WFTGIU PZZ NB MDJTP, MKNPKM PM VPWWTSQB D UPDL(At the time of this writing, no hint was published on the web page). There was definitely a twist in the cryptotext, because the cipher resisted all my attempts to decode it by substituting the letter E (the most common letter in English). Working on words, did not get me much further: substituting the DOJ sequence with THE (or, remembering the twist, its reverse EHT) did not get me much further.
I then tried grep and various pattern matches (based on letter substitutions) on the English dictionary available on Unix, but none seemed to give any useful results.
cd /usr/share/dict grep '^.e.t.$' words grep '^.e.e..e..$' words grep '^.e.e..e..$' words | wc -l grep '^.e....t...e.t.t..t.$' words grep '^......t.....t.t..t.$' words grep '^......e.....e.e..e.$' words grep '^.e..e.t..e.$' words egrep '^.(.)\1$' words grep thte words grep '^eh..e..e..$' words grep '^eh...e..e..$' words grep -i '^eh...e..e..$' words grep '^..a$' words grep '^..i$' words grep '^i..$' words grep '^a..$' words grep '^.a.k.sa..$' words
TOWTHOTZTIDOG 12 1 21 1 2Expressing these as an extended regular expression allowed me to look for such a word in the dictionary:
egrep -i '^(.)(.).\1.\2\1.\1..\2.$' words
INSIGNIFICANT 12 1 21 1 2 TOWTHOTZTIDOGThis gave me many more letters:
W -> S H -> G Z -> F I -> C D -> A G -> TFrom then on, a simple examination of the cyphertext with the replaced letters allowed me to guess more words, and more substitutions.
TODAY, BY RADIO, AND ALSO ON GIANT HOARDINGS, A RABBI, AN ADMIRAL NOTORIOUS FOR HIS LINKS TO MASONRY, A TRIO OF CARDINALS, A TRIO, TOO, OF INSIGNIFICANT POLITICIANS (BOUGHT AND PAID FOR BY A RICH AND CORRUPTANGLO-CANADIAN BANKING CORPORATION) INFORM US ALL OF HOW OUR COUNTRY NOW RISKS DYING OF STARVATION.A RUMOUR, THATS MY INITIAL THOUGHT AS I SWITCH OFF MY RADIO, RUMOUR OR POSSIBLY A HOAX
And the twist? The above text does not contain any instance of the letter E!Read and post comments, or share through