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Blockchain technology has transformed secure data management by employing a decentralized framework that fundamentally depends on cryptographic methods. This paper investigates how hash functions (e.g., SHA-256), digital signatures (e.g., ECDSA), and Merkle trees enable blockchain’s core attributes—immutability, security, and transparency. A Python-based proof-of-concept demonstrates hashing’s pivotal role in linking blocks, ensuring resistance to tampering. The study assesses cryptography’s contributions, such as enhanced security, alongside limitations like quantum vulnerabilities and scalability constraints. It proposes future directions, including post-quantum cryptography and zero-knowledge proofs, to mitigate these challenges. Real-world applications in finance and supply chains highlight practical relevance. Findings confirm cryptography as the bedrock of blockchain, offering insights to bolster its resilience amid evolving technological demands.