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Teams will cryptanalyze and decode encrypted messages using cryptanalysis techniques for historical and modern advanced ciphers.

Regional Location
Eye Protection
Rules Location
Written Test Day
National Rulebook
December 30, 2022

The Rail Fence Cipher - Science Olympiad rules do not define Rail Fence. ACA rules allow encryption to be either writing into the rainfence pattern on the zigzag and reading off on rows, or writing into the pattern on rows and reading off on the zigzag. Are both encryptions allowed?

Only the pattern where the cipher text is written in rows and the plaintext is read through the zigzag is allowed. For example with the cipher text "RFEALECIN" would be written into three rows of "R F E" "ALEC" and "IN" and would be read out via zigzag as "RAILFENCE".

December 30, 2022

Rule 3.e.v. - Relating to the Fractionated Morse Cipher, will it always end with the last letter or will there be an XX at the end to mark the end of the word?

No. For a Fractionated Morse Cipher, the cipher can end with 0,1, or 2 X at the end depending on how many are needed to pad to a group of 3 symbols.


2023 CodeBusters Tournament Resource Sheet
Download PDF • 204KB


National Codebusters Div B event page

National Codebusters Div C event page

Student Resource Center (Scioly)

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