I will try to not directly answer your question, but this exercise is so simple that it gets hard to help you without doing that.

You are going to use a symmetric cipher (One-Time Pad - OTP), thus your initial step is to compute your key.

  This is given by the execution of the LFSR as you described, until a key-stream of the length of the message is obtained.

  Then, simply apply the OTP decryption step into your pair (key, ciphertext).

(I hope you know what the OTP decryption step looks like! ;-)

I will try to not directly answer your question, but this exercise is so simple that it gets hard to help you without doing that.

You are going to use a symmetric cipher (One-Time Pad - OTP), thus your initial step is to compute your key. This is given by the execution of the LFSR as you described, until a key-stream of the length of the message is obtained. Then, simply apply the OTP decryption step ^(*) into your pair (key, ciphertext).

_{^(*) I hope you know what the OTP decryption step looks like! ;-)}

I will try to not directly answer your question, but this exercise is so simple that it gets hard to help you without doing that.

You are going to use a symmetric key (One-Time Pad - OTP), thus your initial step is to compute your key.

This is given by the execution of the LFSR as you described, until a key-stream of the length of the message is obtained.

Then, simply apply the OTP decryption step into your pair (key, ciphertext).

(I hope you know what the OTP decryption step looks like! ;-)

I will try to not directly answer your question, but this exercise is so simple that it gets hard to help you without doing that.

You are going to use a symmetric cipher (One-Time Pad - OTP), thus your initial step is to compute your key.

This is given by the execution of the LFSR as you described, until a key-stream of the length of the message is obtained.

Then, simply apply the OTP decryption step into your pair (key, ciphertext).

(I hope you know what the OTP decryption step looks like! ;-)