1. A method for secure workgroup communication, the method comprising: recording, at a key server, a plurality of public keys associated with a plurality of clients in a workgroup; generating a time-to-live (TTL) value for a workgroup key, wherein the workgroup key is generated by the key server and used to encrypt workgroup communications, and the TTL value indicates a period of time until the workgroup key expires; generating a workgroup key update message, wherein the workgroup key update message includes the workgroup key, a workgroup key version number, and the TTL value for the workgroup key; encrypting the workgroup key update message using at least a subset of the public keys; wherein encrypting the workgroup key update message comprises generating separate ciphertexts for each of the at least a subset of public keys, wherein each ciphertext comprises the workgroup key update message encrypted using a respective public key; and broadcasting the encrypted workgroup key update message to the workgroup.