A computer-implemented method of operating a dealer node to distribute a computation output, the method comprising: providing a respective secret value secret share of a secret value to each of a first evaluator node and a second evaluator node; receiving, from the first evaluator node, a first masked computation output secret share of a masked computation output and a first Message Authentication Code, MAC, secret share of a MAC of the masked computation output, wherein the masked computation output is a function of an output of the computation and a random mask, and wherein the MAC of the masked computation output is a function of the masked computation output and the secret value, the first MAC secret share being formed using the secret value secret share of the first evaluator node; wherein the random mask is determined by the first and the second evaluator nodes; receiving, from the second evaluator node, a second masked computation output secret share of the masked computation output and a second MAC secret share of the MAC of the masked computation output, the second MAC secret share being formed using the secret value secret share of the second evaluator node; verifying the MAC of the masked computation output using the first masked computation output secret share, the first MAC secret share, the second masked computation output secret share, the second MAC secret share, and the secret value, wherein verifying the MAC of the masked computation output comprises combining the first masked computation output secret share and the second masked computation output secret share to determine the first masked computation output; if the MAC of the masked computation output is verified: sending the determined first masked computation output to the first evaluator node and the second evaluator node; receiving, from both the first and the second evaluator node, information to enable the dealer node to determine the output of the computation from the first masked computation output; determining which of the received information is correct, and using correct received information to determine the computation output. providing a respective secret value secret share of a secret value to each of a first evaluator node and a second evaluator node; receiving, from the first evaluator node, a first masked computation output secret share of a masked computation output and a first Message Authentication Code, MAC, secret share of a MAC of the masked computation output, wherein the masked computation output is a function of an output of the computation and a random mask, and wherein the MAC of the masked computation output is a function of the masked computation output and the secret value, the first MAC secret share being formed using the secret value secret share of the first evaluator node; wherein the random mask is determined by the first and the second evaluator nodes; receiving, from the second evaluator node, a second masked computation output secret share of the masked computation output and a second MAC secret share of the MAC of the masked computation output, the second MAC secret share being formed using the secret value secret share of the second evaluator node; verifying the MAC of the masked computation output using the first masked computation output secret share, the first MAC secret share, the second masked computation output secret share, the second MAC secret share, and the secret value, wherein verifying the MAC of the masked computation output comprises combining the first masked computation output secret share and the second masked computation output secret share to determine the first masked computation output; if the MAC of the masked computation output is verified: sending the determined first masked computation output to the first evaluator node and the second evaluator node; receiving, from both the first and the second evaluator node, information to enable the dealer node to determine the output of the computation from the first masked computation output; determining which of the received information is correct, and using correct received information to determine the computation output. sending the determined first masked computation output to the first evaluator node and the second evaluator node; receiving, from both the first and the second evaluator node, information to enable the dealer node to determine the output of the computation from the first masked computation output; determining which of the received information is correct, and using correct received information to determine the computation output.