A system and method for signing a message and establishing a symmetric key between two entities. A plurality of leaves are generated, each including public and private values of a Lamport signature; a plurality of trees are generated each including a subgroup of leaves; leaves of a first nested tree are used for signing messages sent to a second entity. If a first nested tree is exhausted, then a leaf of a following tree is used for signing and a root of the following tree together with an auxiliary value are published, the auxiliary value enabling the second entity to verify that the root of the following tree was generated by the first entity. The symmetric key is generated using a modified Merkel puzzle including a plurality of rows, each including a plurality of hashed values. The modified Merkel puzzle may be signed using a leave of a nested tree.
|State||Published - 9 May 2019|