Hill

I found these characters on top of a hill covered with algae ... bruh I can't figure it out can you help me? wznqca{d4uqop0fk_q1nwofDbzg_eu}

Recon

The flag is encrypted with hill cipher. We know the first 6 characters are utflag, which is encrypted to wznqca.

With this you can construct a matrix that encrypts wznqca to utflag by constructing two equations with two unknowns and then substituting and solving them. The matrix I found is 2x2:

| 1 | 22 |
| 11 | 13 |

And the inverse matrix is:

| 13 | 6 |
| 3  | 21 |

With this we can decrypt the flag.

Flag

utflag{d4nger0us_c1phertext_qq}