A method comprising: requesting, by a second entity comprising a plurality of entities, a confirmation possession token from a first entity, the first entity comprising one of a set of entities, wherein the confirmation possession token is associated with a resource from the first entity; receiving, by the second entity and from the first entity, the confirmation possession token; sending, by the second entity and to a hash chain service that maintains a hash chain associated with the resource, an electronic message with a request to add an expansion node to the hash chain associated with the resource, wherein the expansion node indicates a transfer of a privilege associated with the resource from the first entity to the second entity, wherein the request includes the confirmation possession token of the first entity, wherein a root node is included in a first level of the hash chain, and wherein the root node includes a resource-identifier token that identifies the resource associated with the hash chain; generating, by the hash chain service, a confirmation hash digest based on the confirmation possession token via a hashing function associated with the hash chain; verifying, by the hash chain service, the confirmation hash digest matches a predecessor hash digest indicated in a predecessor node of the hash chain, wherein the hashing function maps a predecessor possession token to the predecessor hash digest, wherein the predecessor node includes an identifier of the first entity, wherein the identifier identifies the first entity has a privilege associated with the resource; and linking, by the hash-chain service, the expansion node to the predecessor node at a second level of the hash chain, wherein the expansion node indicates the predecessor possession token, a successor hash digest, and an identifier that identifies the second entity, wherein each entity of the plurality of entities comprised in the second entity has a corresponding node at the second level of the hash chain, wherein each node includes an identifier of the corresponding entity as a member element of the second entity, wherein the successor hash digest is based on a successor possession token, and wherein the link is implemented by setting a pointer that is a member element of the predecessor node to a memory address of the expansion node, or by setting a pointer that is a member element of the expansion node to a memory address of the predecessor node. requesting, by a second entity comprising a plurality of entities, a confirmation possession token from a first entity, the first entity comprising one of a set of entities, wherein the confirmation possession token is associated with a resource from the first entity; receiving, by the second entity and from the first entity, the confirmation possession token; sending, by the second entity and to a hash chain service that maintains a hash chain associated with the resource, an electronic message with a request to add an expansion node to the hash chain associated with the resource, wherein the expansion node indicates a transfer of a privilege associated with the resource from the first entity to the second entity, wherein the request includes the confirmation possession token of the first entity, wherein a root node is included in a first level of the hash chain, and wherein the root node includes a resource-identifier token that identifies the resource associated with the hash chain; generating, by the hash chain service, a confirmation hash digest based on the confirmation possession token via a hashing function associated with the hash chain; verifying, by the hash chain service, the confirmation hash digest matches a predecessor hash digest indicated in a predecessor node of the hash chain, wherein the hashing function maps a predecessor possession token to the predecessor hash digest, wherein the predecessor node includes an identifier of the first entity, wherein the identifier identifies the first entity has a privilege associated with the resource; and linking, by the hash-chain service, the expansion node to the predecessor node at a second level of the hash chain, wherein the expansion node indicates the predecessor possession token, a successor hash digest, and an identifier that identifies the second entity, wherein each entity of the plurality of entities comprised in the second entity has a corresponding node at the second level of the hash chain, wherein each node includes an identifier of the corresponding entity as a member element of the second entity, wherein the successor hash digest is based on a successor possession token, and wherein the link is implemented by setting a pointer that is a member element of the predecessor node to a memory address of the expansion node, or by setting a pointer that is a member element of the expansion node to a memory address of the predecessor node.