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MARTINA Crack the ******

This challenge can be found on the inside of the cover of issue 2.

The Setup

We are given a 6-letter cipher to crack, and a phrase made up of five 5-letter words.

The Square

The page given in the cover gives us a hint: it mentions the Polybius square.

This page leads us to discover the Bifid cipher.

Let's try the decryption method for this cipher:

| \ | 1 | 2 | 3 | 4 | 5 |
| - | - | - | - | - | - |
| 1 | D | W | A | R | F |
| 2 | G | L | Y | P | H |
| 3 | J | O | C | K | S |
| 4 | M | U | N | T | Z |
| 5 | V | I | B | E | X |

The ciphertext is ZKSWIE, whose letters are represented by the coordinates:

45 34 35 12 52 54

We find the midpoint and move both halves on top of each other:

45 34 35
12 52 54

We read out the columns as coordinates:

41 52 35 42 35 54

Which gives us our flag when translated with the table!