Question about decrypting file with pem file or key file

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1

hello, I am trying to decipher a message.txt file of a challenge I am practicing crypto. I am given a .pem file with a private key and a .key file that appears to be symmetric (it is in BASE64).
I have tried quite a few combinations with OpenSSL but have not been able to come up with anything, what procedures should I follow? I am new to this crypto stuff, but I am interested in learning.

The message looks like this:

image
image953×135 44.4 KB

2

Hi,
did you asked ChatGPT?. Furthermore, it is recommended to attach the exact commands you used followed by the error.

3

Yes, I did that quite a bit.
The command that I used quite a lot in different variants is:
'openssl pkeyutl -decrypt -inkey private_key.pem -in message.txt -out decrypted.txt ’ but it returned the response ‘bad magic number’.