A computer-implemented method for a node (i) of a blockchain network, the method implemented on a node of a blockchain network, said node (i) having a plurality of interfaces (a, b, c, d, e) connected to peer nodes, the computer-implemented method comprising: determining a correlation matrix having correlation coefficients representing the correlation between data processed at each interface (a,b,c,d,e) of said node, wherein the correlation coefficient represents the correlation between transactions between each pair of interfaces; receiving data at a receiving interface of said node (i); selecting at least one of a plurality of other interfaces (a,b,c,d,e) of said node, and relaying said received data to the selected at least one interface, wherein the at least one interface is selected according to a set of the correlation coefficients of the receiving interfaces, wherein relaying data is further based on at least one of (i) a reset time, the time during which full transaction relay will be performed; and, (ii) a change time, being the average time between two or more consecutivechange events, the change events including at least one of: a new peer node connecting to an interface; a terminated connection to an interface; and an interface connecting to a node categorised or judged to be malicious, wherein the correlation matrix is reset once every change time; and wherein data is relayed to all interfaces during the reset time after the correlation matrix has been reset before starting to select the interfaces according to the set of correlation coefficients again. determining a correlation matrix having correlation coefficients representing the correlation between data processed at each interface (a,b,c,d,e) of said node, wherein the correlation coefficient represents the correlation between transactions between each pair of interfaces; receiving data at a receiving interface of said node (i); selecting at least one of a plurality of other interfaces (a,b,c,d,e) of said node, and relaying said received data to the selected at least one interface, wherein the at least one interface is selected according to a set of the correlation coefficients of the receiving interfaces, wherein relaying data is further based on at least one of (i) a reset time, the time during which full transaction relay will be performed; and, (ii) a change time, being the average time between two or more consecutivechange events, the change events including at least one of: a new peer node connecting to an interface; a terminated connection to an interface; and an interface connecting to a node categorised or judged to be malicious, wherein the correlation matrix is reset once every change time; and wherein data is relayed to all interfaces during the reset time after the correlation matrix has been reset before starting to select the interfaces according to the set of correlation coefficients again. (i) a reset time, the time during which full transaction relay will be performed; and, (ii) a change time, being the average time between two or more consecutivechange events, the change events including at least one of: a new peer node connecting to an interface; a terminated connection to an interface; and an interface connecting to a node categorised or judged to be malicious, wherein the correlation matrix is reset once every change time; and wherein data is relayed to all interfaces during the reset time after the correlation matrix has been reset before starting to select the interfaces according to the set of correlation coefficients again. a new peer node connecting to an interface; a terminated connection to an interface; and an interface connecting to a node categorised or judged to be malicious, wherein the correlation matrix is reset once every change time; and wherein data is relayed to all interfaces during the reset time after the correlation matrix has been reset before starting to select the interfaces according to the set of correlation coefficients again.