The widespread distribution and ease of modification of digital content have led to increasing instances of copyright infringement and unauthorized use, posing significant challenges to intellectual property (IP) protection and ownership preservation. Non-Fungible Tokens (NFTs) offer promising potential in this domain by enhancing the efficiency of copyright registration and improving the transparency and liquidity of digital content transactions. However, existing NFT-based copyright protection mechanisms predominantly rely on tokens minted by third-party platforms, which are vulnerable to various security threats. In this paper, we propose a multi-layered blockchain security framework designed to safeguard users from risks such as illegal duplication, IP infringement, and malware attacks during the acquisition of NFT assets. Our approach involves a comprehensive analysis of the smart contracts, metadata, and digital assets that constitute NFTs. To further strengthen the system, we introduce a Schnorr-based multi-signature scheme that enables collaborative transaction signing, thereby reducing single-point vulnerabilities and enhancing transparency. The proposed framework effectively ensures integrity, ownership, and copyright protection of digital content in NFT ecosystems.