A commitment scheme enables a sender to transmit an encrypted message, known as a commitment, in such a way that its contents remain concealed until the sender provides the necessary opening information. Furthermore, there is only one valid way to open the commitment. In this chapter, we examine a scenario where the sender transmits the commitment (e.g., over a computer network) while an adversary has the ability to actively tamper with it. Specifically, the adversary can intercept the commitment C, modify it, and generate a new commitment \(C'\) that encodes a message related to the original content of C. A non-malleable commitment scheme mitigates this type of attack. In this chapter, we propose a secure non-malleable commitment scheme that remains secure even when the adversary can eavesdrop on multiple commitments and subsequently compute and send multiple commitments. The construction relies on the existence of sub-exponentially hard one-way permutations.