A certificateless public key cryptosystem can make a special contribution to building key distribution and management architecture in resource-constrained mobile ad hoc networks (MANETs) because it has no separate certificate and no complex certificate management problems. In this paper, we present a virtual private key generator (VPKG)-based escrow-free certificateless public key cryptosystem as a novel combination of certificateless and threshold cryptography. Using secret sharing, we build a VPKG whose members collaboratively calculate the partial private key and send it to the user via public channels. The private key of a user is generated jointly by the VPKG and the user. Each of them has “half” of the secret information about the private key of the user. In addition, binding a user's public key with its identity and partial private key, respectively, raises our schemes to the same trust level as is enjoyed in a traditional public key infrastructure. We also show that the proposed scheme is secure against public key replacement attacks and passive attacks. Copyright © 2012 John Wiley & Sons, Ltd.