My question is that thhe ciphertext AAAAFXGGFAFFGGFGXAFGADGGAXXXFX was encrypted using the ADFGX cipher with the 55 matrix and the keyword broken. Find the plaintext

I saw an expert's answer, but I don't get this part. can you explain in detail? Thank you

To decrypt the ciphertext, we need to reverse the process. The first step is to undo the transposition of the columns and rows by reading the ciphertext in columns according to the order of the keyword "broken". In your case, the ciphertext is AAAAFXGGFAFFGGFGXAFGADGGAXXXFX, so the columns will be read as AAFGXXAFGGAFAGFGGXDGGAXFX.

Then, we need to use the matrix to convert the ciphertext back into the original digrams of plaintext. To do this, we look up the position of each pair of letters in the matrix and find the corresponding digram.

Finally, we get the plaintext:

AAAFGXAFGGAFAGFGGXDGGAXFX -> "brokenpassword"