Systems and methods are described for implementing communication of data between a group of users in a communication system. In one implementation, a plurality of quorum portions of a private group signing key are generated and provided to each of a plurality of devices of the group of users, wherein a group digital signature is reconstructed from a predetermined minimum number of encrypted portions of the group digital signature, each generated by a respective device of the group of users using a corresponding quorum portion of the private group signing key. Each user device may digitally sign group output data using a respective private group signing key portion. A reconstructed group digital signature may be verified using a corresponding public group signing key. Other embodiments are also described and claimed.