Method and apparatus for communications using secret key in communication system

An operation method of a first communication node in a communication system, the operation method comprising:

• transmitting a first pilot signal to a second communication node;
• estimating a channel state between the first communication node and the second communication node based on a second pilot signal received from the second communication node;
• generating a first channel codebook based on the estimated channel state;
• receiving information of a second channel codebook generated based on a channel state estimated based on the first pilot signal from the second communication node;
• when a size of the second channel codebook is equal to or less than a size of the first channel codebook, adjusting the size of the first channel codebook to be equal to the size of the second channel codebook;
• and
• transmitting an acknowledgment (ACK) indicating that the second channel codebook is to be used to the second communication node.

A first communication node in a communication system, the first communication node comprising:

• a channel estimator estimating a channel state between the first communication node and a second communication node based on a pilot signal received from the second communication node;
• a channel codebook generator generating a first channel codebook based on the estimated channel state;
• a secret key codebook generator generating a secret key based on the first channel codebook;
• an encryptor performing an encryption operation on transmission data by using the secret key;
• and
• a decryptor performing a decryption operation on reception data by using the secret key.