A method comprising: generating an authenticated data structure of a distributed digital ledger transaction network, wherein the authenticated data structure comprises a data tree comprising nodes having data representations mapped to entries in a database; performing lazy deletion of data from the authenticated data structure by: accessing a data representation from a node of the data tree to determine expiration of an eviction date associated with the node; and in response to determining expiration of the eviction date, deleting one or more entries corresponding to the node from the database while maintaining the data representation within the data tree, characterised in that: prior to deleting the one or more entries corresponding to the node from the database: receiving a request from a client device, the request requiring use of the one or more entries; in response to receiving the request from the client device, accessing the data representation from the node of the data tree to determine expiration of the eviction date; and processing the request as if the one or more entries have been deleted. generating an authenticated data structure of a distributed digital ledger transaction network, wherein the authenticated data structure comprises a data tree comprising nodes having data representations mapped to entries in a database; performing lazy deletion of data from the authenticated data structure by: accessing a data representation from a node of the data tree to determine expiration of an eviction date associated with the node; and in response to determining expiration of the eviction date, deleting one or more entries corresponding to the node from the database while maintaining the data representation within the data tree, characterised in that: prior to deleting the one or more entries corresponding to the node from the database: receiving a request from a client device, the request requiring use of the one or more entries; in response to receiving the request from the client device, accessing the data representation from the node of the data tree to determine expiration of the eviction date; and processing the request as if the one or more entries have been deleted. accessing a data representation from a node of the data tree to determine expiration of an eviction date associated with the node; and in response to determining expiration of the eviction date, deleting one or more entries corresponding to the node from the database while maintaining the data representation within the data tree, characterised in that: prior to deleting the one or more entries corresponding to the node from the database: receiving a request from a client device, the request requiring use of the one or more entries; in response to receiving the request from the client device, accessing the data representation from the node of the data tree to determine expiration of the eviction date; and processing the request as if the one or more entries have been deleted. receiving a request from a client device, the request requiring use of the one or more entries; in response to receiving the request from the client device, accessing the data representation from the node of the data tree to determine expiration of the eviction date; and processing the request as if the one or more entries have been deleted.