We present a new efficient paradigm for signing digital streams. The problem of signing digital streams to prove their authenticity is substantially different from the problem of signing regular messages. Traditional signature schemes are message oriented and require the receiver to process the entire message before being able to authenticate its signature. However, a stream is a potentially very long ( or infinite) sequence of bits that the sender sends to the receiver and the receiver is required to consumes the received bits at more or less the input rate and without excessive delay. Therefore it is infeasible for the receiver to obtain the entire stream before authenticating and consuming it. Examples of streams include digitized video and audio files, data feeds and applets. We present two solutions to the problem of authenticating digital streams. The first one is for the case of a finite stream which is entirely known to the sender (say a movie). We use this constraint to devise...

In this work, we aim to reduce the computational costs of using public-key digital signatures in securing routing protocols. Two protocols (COSP and IOSP) using one-time digital signatures are introduced to provide the functionality of public-key digital signatures. Our protocols are intended to be used in place of public-key digital signatures for signing all kinds of message exchanges among routers. We obtained more than ten-fold increase in speed compared with public-key signatures. Our protocols overcome the shortcomings identified in previous works, such as timing constraints, limited applications and high storage and computational costs for volatile environments [12].

One-time signature schemes have found numerous applications: in ordinary, on-line/off-line, and forward-secure signatures. More recently, they have been used in multicast and broadcast authentication. We propose a one-time signature scheme with very efficient signing and verifying, and short signatures. Our scheme is well-suited for broadcast authentication, and, in fact, can be viewed as an improvement of the BiBa one-time signature (proposed by Perrig in CCS 2001 for broadcast authentication).

We introduce the notion of multi-trapdoor commitments which is a stronger form of trapdoor commitment schemes. We then construct two very e#cient instantiations of multi-trapdoor commitment schemes, based on the Strong RSA Assumption and the recently introduced Strong Di#e-Hellman Assumption.

Abstract. Essentially all known one-time signature schemes can be described as special instances of a general scheme suggested by Bleichenbacher and Maurer based on “graphs of one-way functions”. Bleichenbacher and Maurer thoroughly analyze graph based signatures from a combinatorial point of view, studying the graphs that result in the most efficient schemes (with respect to various efficiency measures, but focusing mostly on key generation time). However, they do not give a proof of security of their generic construction, and they leave open the problem of determining under what assumption security can be formally proved. In this paper we analyze graph based signatures from a security point of view and give sufficient conditions that allow to prove the security of the signature scheme in the standard complexity model (no random oracles). The techniques used to prove the security of graph based one-time signatures are then applied to the construction of a new class of algebraic signature schemes, i.e., schemes where signatures can be combined with a restricted set of operations. 1

We provide a positive result about the Fiat-Shamir (FS) transform in the standard model, showing how to use it to convert three-move identification protocols into two-tier signature schemes with a proof of security that makes a standard assumption on the hash function rather than modeling it as a random oracle. The result requires security of the starting protocol against concurrent attacks. We can show that numerous protocols have the required properties and so obtain numerous efficient two-tier schemes. Our first application is a two-tier scheme based efficient transform of any unforgeable signature scheme into a strongly unforgeable one. (This extends Boneh, Shen and Waters [BSW06] whose transform only applies to a limited class of schemes.) The second application is new one-time signature schemes that, compared to one-way function based ones of the same computational cost, have smaller key and signature sizes. Keywords: Fiat-Shamir transform, signatures, identification protocols, one-time signatures.

Abstract. One-time proxy signatures are one-time signatures for which a primary signer can delegate his or her signing capability to a proxy signer. In this work we propose two one-time proxy signature schemes with different security properties. Unlike other existing one-time proxy signatures that are constructed from public key cryptography, our proposed schemes are based one-way functions without trapdoors and so they inherit the communication and computation efficiency from the traditional one-time signatures. Although from a verifier point of view, signatures generated by the proxy are indistinguishable from those created by the primary signer, a trusted authority can be equipped with an algorithm that allows the authority to settle disputes between the signers. In our constructions, we use a combination of one-time signatures, oblivious transfer protocols and certain combinatorial objects. We characterise these new combinatorial objects and present constructions for them. 1

We give a direct construction of digital signatures based on the complexity of approximating the shortest vector in ideal (e.g., cyclic) lattices. The construction is provably secure based on the worst-case hardness of approximating the shortest vector in such lattices within a polynomial factor, and it is also asymptotically efficient: the time complexity of the signing and verification algorithms, as well as key and signature size is almost linear (up to poly-logarithmic factors) in the dimension n of the underlying lattice. Since no sub-exponential (in n) time algorithm is known to solve lattice problems in the worst case, even when restricted to cyclic lattices, our construction gives a digital signature scheme with an essentially optimal performance/security trade-off.

One-time signatures have been known for more than two decades, and have been studied mainly due to their theoretical value. Recent works motivated us to examine the practical use of one-time signatures in high-performance applications. In this paper we describe FMTseq — a signature scheme that merges recent improvements in hash tree traversal into Merkle’s one-time signature scheme. Implementation results show that the scheme provides a signature speed of up to 35 times faster than a 2048-bit RSA signature scheme, for about one million signatures, and a signature size of only a few kilobytes. We provide an analysis of practical parameter selection for the scheme, and improvements that can be applied in more specific scenarios.

This paper analyzes and improves the recently proposed bins and balls signature (BiBa [23]), a new approach for designing signatures from one-way functions without trapdoors.