Identifying properties of a communication device

A computer-implemented method of identifying a property of a communication device, the method comprising:

• receiving a character string that identifies the communication device;
• searching a data structure having multiple nodes, wherein at least some of the nodes store a hash value, wherein the data structure stores hash values of a minimal set of substrings that allows unique identification of each of a plurality of communication devices in training data used to create the data structure, and wherein the searching comprises iteratively performing the following operations for each of a plurality of nodes of the data structure:
• performing a hash function on a sequence of characters in the received character string to generate a hash value,
• comparing the generated hash value with the hash value stored by the node, and
• identifying a next node of the data structure to evaluate based on a result of the comparison;
• and
• identifying a property of the communication device, wherein the property is associated with a node identified by searching the data structure.

A non-transitory computer-readable medium comprising information for use in identifying a property of a communication device, the communication device being arranged to transmit a character string that identifies the communication device, the character string comprising a plurality of substrings, each substring comprising a sequence of characters, wherein the information comprises:

• a data structure having multiple nodes, wherein:
• each of a plurality of nodes of the data structure stores a respective hash value, wherein each hash value corresponds to the hash value that would be generated by performing a hash function on the sequence of characters of each substring;
• the data structure stores hash values of a minimal set of substrings that allows unique identification of each of a plurality of communication devices in training used to create a data structure;
• the data structure comprises references between the plurality of nodes, wherein the references define a path through the data structure that identifies the communication device;
• and
• a node on the path is associated with a property of the communication device.