A computer-implemented method to increase security of a blockchain-implemented transaction, in a network comprising a dealer node, and a plurality of participating nodes each having its own public key and private key, the method comprising: for each of a plurality of cycles, obtaining a set of output addresses by: at the dealer node, ordering said participating nodes such that there exists a cycle node order, designating a first node in the node order as a message originator, and the last node as a propagator, and designating one of the remaining participating nodes as a selector, wherein each node is not the propagator in more than one cycle order, at the message originator, generating ciphertext comprising a nested encrypted first message and a nested encrypted second message, each message comprising one or more transaction options, and transmitting said ciphertext to a next participating node in said cycle node order, transmitting said ciphertext from node to node in said cycle node order, each node decrypting the ciphertext before transmitting it, wherein the selector additionally removes, 640) one of the nested encrypted messages from the ciphertext before transmitting it, and at the propagator, decrypting the remaining single message to obtain the one or more transaction optionscontained in the message, and outputting (730, 740) the transaction options as one or more propagator outputs; at all the nodes designated as propagator, generating a shuffled order of the propagator outputs obtained from all the cycles; and generating a blockchain transaction wherein each output of the transaction is based on one of the propagator outputs, and the outputs are ordered according to the shuffled order. for each of a plurality of cycles, obtaining a set of output addresses by: at the dealer node, ordering said participating nodes such that there exists a cycle node order, designating a first node in the node order as a message originator, and the last node as a propagator, and designating one of the remaining participating nodes as a selector, wherein each node is not the propagator in more than one cycle order, at the message originator, generating ciphertext comprising a nested encrypted first message and a nested encrypted second message, each message comprising one or more transaction options, and transmitting said ciphertext to a next participating node in said cycle node order, transmitting said ciphertext from node to node in said cycle node order, each node decrypting the ciphertext before transmitting it, wherein the selector additionally removes, 640) one of the nested encrypted messages from the ciphertext before transmitting it, and at the propagator, decrypting the remaining single message to obtain the one or more transaction optionscontained in the message, and outputting (730, 740) the transaction options as one or more propagator outputs; at the dealer node, ordering said participating nodes such that there exists a cycle node order, designating a first node in the node order as a message originator, and the last node as a propagator, and designating one of the remaining participating nodes as a selector, wherein each node is not the propagator in more than one cycle order, at the message originator, generating ciphertext comprising a nested encrypted first message and a nested encrypted second message, each message comprising one or more transaction options, and transmitting said ciphertext to a next participating node in said cycle node order, transmitting said ciphertext from node to node in said cycle node order, each node decrypting the ciphertext before transmitting it, wherein the selector additionally removes, 640) one of the nested encrypted messages from the ciphertext before transmitting it, and at the propagator, decrypting the remaining single message to obtain the one or more transaction optionscontained in the message, and outputting (730, 740) the transaction options as one or more propagator outputs; at all the nodes designated as propagator, generating a shuffled order of the propagator outputs obtained from all the cycles; and generating a blockchain transaction wherein each output of the transaction is based on one of the propagator outputs, and the outputs are ordered according to the shuffled order.