As the digital ecosystem becomes increasingly reliant on centralized cloud infrastructure, the vulnerabilities associated with single points of failure, data sovereignty, and privacy intrusion have become critical bottlenecks. This paper introduces SentinelStore, a novel decentralized storage protocol designed to shift the trust boundary entirely to the client edge. Unlike traditional distributed systems that rely on full-file replication, SentinelStore implements a Zero-Knowledge Architecture by performing all cryptographic operations—key generation, authenticated encryption, and Shamir’s Secret Sharing (SSS)—directly within the user’s browser. This ensures that the storage network remains mathematically oblivious to the data it holds. We propose a hybrid storage model that utilizes a Kademlia-based Distributed Hash Table (DHT) for resilient shard distribution and a metadata coordinator for access control, without compromising the zero-trust principle. Furthermore, we introduce an innovative Dynamic Re-sharding Orchestration mechanism, allowing administrators to mathematically alter the fault-tolerance parameters of stored data without decrypting it or requiring client intervention. Experimental results demonstrate that this architecture achieves information-theoretic security and high availability with significantly lower storage overhead compared to traditional replication strategies.