Authors:
Marek Karpinski
and
Yakov Nekrich†
Affiliation:
University of Bonn, Germany
Keyword(s):
Identification and Authentication, Merkle Trees, Public Key Signatures, Authentication Path, Fractal Tree Traversal, Trade-off, Amortization.
Related
Ontology
Subjects/Areas/Topics:
Cryptographic Techniques and Key Management
;
Information and Systems Security
Abstract:
In this paper we describe optimal trade-offs between time and space complexity of Merkle tree traversals with their associated authentication paths, improving on the previous results of Jakobsson, Leighton, Micali, and Szydlo (Jakobsson et al., 03) and Szydlo (Szydlo, 04). In particular, we show that our algorithm requires 2 log n/ log(3) n hash function computations and storage for less than (log n/ log(3) n + 1) log log n + 2 log n hash values, where n is the number of leaves in the Merkle tree. We also prove that these trade-offs are optimal, i.e. there is no algorithm that requires less than O(log n/ log t) time and less than O(t log n/ log t) space for any choice of parameter t ≥ 2. Our algorithm could be of special use in the case when both time and space are limited.