The security of digital signature schemes that are used today depends on the security of cryptographic hash functions and the intractability of certain number theoretic problems. In this talk CMSS, an efficient version of the Merkle signature scheme from the late seventies, is presented whose security only relies on the existence of secure cryptographic hash functions and pseudo random number generators. It is shown that the efficiency of CMSS is competitive to RSA and ECDSA. This raises the question of whether it is possible and useful to eliminate number theory from digital signature schemes.