Threshold cryptography provides a more secure method of ensuring the cloud storage, through sharing cryptographic keys with a number of participants, none of whom can have the system compromised. The paper is a probabilistic analysis of threshold-based schemes to assess the reliability, security resilience and fault tolerance of these schemes in the presence of different adversarial conditions. The framework suggested describes the important reconstruction probability, share compromise probability, and availability of the system in stochastic distribution and in the form of combinatorics. Using parameters like threshold value, node failure rate, and the strength of adversary, the study illustrates that optimal choice of threshold value contributes much in data confidentiality and at the same time, accessibility. Experimental assessment shows enhanced resistance to partial breaches, and minimized the risk of key exposure as compared to centralized models. The results present a mathematically based basis of constructing safe, scalable and fault-tolerant cloud-based storage systems with the help of threshold cryptography.