A method for collecting data from a group of entitled members, the method comprising: receiving, by a collection unit, a message, and a message signature; validating, by the collection unit, whether the message was received from one of the entitled members of the group, without identifying an entitled member that sent the message, wherein the validating comprises applying a second plurality of mathematical operations on a first group of secrets, a second group of secrets and a first part of the message signature; rejecting, by the collection unit, the message when the message was not received from any entitled member of the group; and collecting data embedded in the message when the message was received from one of the entitled members of the group; wherein a message signature received from the entitled member comprises a first part, and a second part; wherein the second part is generated using a secret key; wherein the secret key is calculated by applying a first plurality of mathematical operations on first member secrets allocated to the entitled member, second member secrets allocated to the entitled member, and a random vector; wherein the first plurality of mathematical operations comprises calculation of products of multiplications of factors that have bases and random exponents; wherein the first member secrets are calculated based on secrets from the first group of secrets allocated to the group, and a subset of random vectors allocated to the entitled member; wherein the second member secrets are calculated based on secrets from the second group of secrets allocated to the group, and the subset of random vectors allocated to the entitled member; wherein the first member secrets and the second member secrets are calculated by applying a modulo operation and additional operations; and wherein the collection unit has access to the first group of secrets and the second group of secrets but is unaware of an allocation of first member secrets and second member secrets to the entitled members of the group. receiving, by a collection unit, a message, and a message signature; validating, by the collection unit, whether the message was received from one of the entitled members of the group, without identifying an entitled member that sent the message, wherein the validating comprises applying a second plurality of mathematical operations on a first group of secrets, a second group of secrets and a first part of the message signature; rejecting, by the collection unit, the message when the message was not received from any entitled member of the group; and collecting data embedded in the message when the message was received from one of the entitled members of the group; wherein a message signature received from the entitled member comprises a first part, and a second part; wherein the second part is generated using a secret key; wherein the secret key is calculated by applying a first plurality of mathematical operations on first member secrets allocated to the entitled member, second member secrets allocated to the entitled member, and a random vector; wherein the first plurality of mathematical operations comprises calculation of products of multiplications of factors that have bases and random exponents; wherein the first member secrets are calculated based on secrets from the first group of secrets allocated to the group, and a subset of random vectors allocated to the entitled member; wherein the second member secrets are calculated based on secrets from the second group of secrets allocated to the group, and the subset of random vectors allocated to the entitled member; wherein the first member secrets and the second member secrets are calculated by applying a modulo operation and additional operations; and wherein the collection unit has access to the first group of secrets and the second group of secrets but is unaware of an allocation of first member secrets and second member secrets to the entitled members of the group.