Smart Grid provides a reliable and efficient end-toend delivery system. Data on each user's unique electricity consumption is given in real time. It also enables utilities to control and monitor the electrical system in real-time, helping them to reduce power outages. Users' privacy is a significant issue in addition to the usual security issues. Data about power usage may be used to infer private information about users by entities with access to the data. To solve these problems, a Block-Chain-based Secure Smart Grid Network (BCS-SGN) has been created, utilizing group signatures and covert channel permission to guarantee user validity. Initially, the data from the smart grid network will be collected and encrypted using blowfish techniques. After encryption, the encrypted data will be stored in the block chain network, which also stores the transmission logs. In order to utilize the security controller, smart contracts are analyzed using smart grid devices. DES, AES, and BCS-SGN are widely used. Symmetric key algorithms are properly compared in this study. Additionally, the metrics of encryption/decryption time, computational time, and throughput are also compared. The percentage of the proposed method, BCS-SGN, is 20%, AES is 15%, and DES is 12%. These outcomes demonstrate that the proposed BCS-SGN outperforms other techniques.