Steganographic Storage System ensures data confidentiality while allowing users to deny the existence of data under coercion. Existing methods are often challenged by multiple snapshot attacks and performance overhead. To address these issues, we propose HiddenStor, a Steganographic Storage System based on secret sharing. Unlike other schemes, HiddenStor features a deniable encryption scheme that uses high-order polynomial secret sharing to obscure the use of lower-order sharing, thereby enhancing the security of confidential data. In addition, HiddenStor is implemented in hardware, eliminating the need to maintain additional metadata. Therefore, HiddenStor can be transparent to the user, and the user’s disk read and write operations remain the same as if HiddenStor had not been used. For compatibility with different operating environments, HiddenStor uses a file-based configuration module that allows users to configure it by simply writing files directly, without the need for additional configuration manangenet software. Performance evaluations show that HiddenStor achieves significant improvements in both security and performance over existing solutions.