Constant-round nonmalleable commitments from any one-way function

We show unconditionally that the existence of commitment schemes implies the existence of constant-round nonmalleable commitments; earlier protocols required additional assumptions such as collision-resistant hash functions or subexponential one-way functions. Our protocol also satisfies the stronger notions of concurrent nonmalleability and robustness. As a corollary, we establish that constant-round nonmalleable zero-knowledge arguments for NP can be based on one-way functions and constant-round secure multiparty computation can be based on enhanced trapdoor permutations; also here, earlier protocols additionally required either collision-resistant hash functions or subexponential one-way functions.