Given that the ciphertext KHOOR ZRUOG was encrypted using a Cæsar cipher, what is the key equivocation? Clearly there are 26 possible keys; here is the decryption of the ciphertext for each key:
| key | plaintext | key | plaintext | key | plaintext |
|---|---|---|---|---|---|
| A | KHOOR ZRUOG | R | TQXXA IADXP | J | BYFFI QILFX |
| Z | LIPPS ASVPH | Q | URYYB JBEYQ | I | CZGGJ RJMGY |
| Y | MJQQT BTWQI | P | VSZZC KCFZR | H | DAHHK SKNHZ |
| X | NKRRU CUXRJ | O | WTAAD LDGAS | G | EBIIL TLOIA |
| W | OLSSV DVYSK | N | XUBBE MEHBT | F | FCJJM UMPJB |
| V | PMTTW EWZTL | M | YVCCF NFICU | E | GDKKN VNQKC |
| U | QNUUX FXAUM | L | ZWDDG OGJDV | D | HELLO WORLD |
| T | ROVVY GYBVN | K | AXEEH PHKEW | C | IFMMP XPSME |
| S | SPWWZ HZCWO | B | JGNNQ YQTNF |
Assuming the plaintext is ordinary English (and not a code), the only possible plaintext is HELLO WORLD and the key is D.
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