A cryptosystem is a structure or scheme consisting of a set of algorithms that converts plaintext to ciphertext to encode or decode messages securely. The cryptosystem points at a computer system that employs cryptography. Cryptosystems are classified by the method they use to encrypt data. One of them is symmetric key encryption. While the symmetric key algorithm uses the same key for encryption and decryption, asymmetric key encryption or public-key encryption uses the different keys. So it is more reliable than symmetric cipher algorithm. In this paper, we propose a new public-key cryptosystem by using LCD codes and explain the signature protocol based on this system which is reliable.