HIBE Scheme Research Articles

A Generic Approach to Build Revocable Hierarchical Identity-Based Encryption

Revocable hierarchical identity-based encryption (RHIBE) is an extension of HIBE that provides the efficient key revocation function by broadcasting an update key per each time period. Many RHIBE schemes have been proposed by combining an HIBE scheme and a tree-based revocation method, but a generic method for constructing an RHIBE scheme has not been proposed. In this paper, we show for the first time that it is possible to construct RHIBE schemes by generically combining underlying cryptographic primitives and tree-based revocation methods. We first generically construct an RHIBE-CS scheme by combining HIBE schemes and the complete subtree (CS) method, and prove the adaptive security by using the adaptive security of the HIBE schemes. Thus, we obtain RHIBE schemes under the quadratic residuosity assumption, CDH assumption, and factoring assumption. Next, we generically construct an RHIBE-SD scheme with shorter update keys by combining HIBE and hierarchical single revocation encryption (HSRE) schemes, and the subset difference (SD) method to reduce the size of update keys. Finally, we generically construct an RHIBE-CS scheme with shorter ciphertexts by combining HIBE schemes with constant-size ciphertext and the CS method. Through different kind of generic combinations, we obtain various RHIBE schemes that provide a trade-off between shorter ciphertexts and shorter update keys.

Adaptively secure revocable hierarchical IBE from k-linear assumption

Revocable identity-based encryption (RIBE) is an extension of IBE with an efficient key revocation mechanism. Revocable hierarchical IBE (RHIBE) is its further extension with key delegation functionality. Although there are various adaptively secure pairing-based RIBE schemes, all known hierarchical analogues only satisfy selective security. In addition, the currently known most efficient adaptively secure RIBE and selectively secure RHIBE schemes rely on non-standard assumptions, which are referred to as the augmented DDH assumption and q-type assumptions, respectively. In this paper, we propose a simple but effective design methodology for RHIBE schemes. We provide a generic design framework for RHIBE based on an HIBE scheme with a few properties. Fortunately, several state-of-the-art pairing-based HIBE schemes have the properties. In addition, our construction preserves the sizes of master public keys, ciphertexts, and decryption keys, as well as the complexity assumptions of the underlying HIBE scheme. Thus, we obtain the first RHIBE schemes with adaptive security under the standard k-linear assumption. We prove adaptive security by developing a new proof technique for RHIBE. Due to the compactness-preserving construction, the proposed R(H)IBE schemes have similar efficiencies to the most efficient existing schemes.

Adaptively Secure Efficient (H)IBE over Ideal Lattice with Short Parameters.

Identity-based encryption (IBE), and its hierarchical extension (HIBE), are interesting cryptographic primitives that aim at the implicit authentication on the users’ public keys by using users’ identities directly. During the past several decades, numerous elegant pairing-based (H)IBE schemes were proposed. However, most pairing-related security assumptions suffer from known quantum algorithmic attacks. Therefore, the construction of lattice-based (H)IBE became one of the hot directions in recent years. In the setting of most existing lattice-based (H)IBE schemes, each bit of a user’s identity is always associated with a parameter matrix. This always leads to drastic but unfavorable increases in the sizes of the system public parameters. To overcome this issue, we propose a flexible trade-off mechanism between the size of the public parameters and the involved computational cost using the blocking technique. More specifically, we divide an identity into segments and associate each segment with a matrix, while increasing the lattice modulo slightly for maintaining the same security level. As a result, for the setting of 160-bit identities, we show that the size of the public parameters can be reduced by almost 89.7% (resp. 93.8%) while increasing the computational cost by merely 5.2% (resp. 12.25%) when is a set of 16 (resp. 8). Finally, our IBE scheme is extended to an HIBE scheme, and both of them are proved to achieve the indistinguishability of ciphertexts against adaptively chosen identity and chosen plaintext attack (IND-ID-CPA) in the standard model, assuming that the well-known ring learning with error (RLWE) problem over the involved ideal lattices is intractable, even in the post-quantum era.

Revocable hierarchical identity-based encryption with shorter private keys and update keys

Revocable hierarchical identity-based encryption (RHIBE) is an extension of HIBE that supports the revocation of user’s private keys to manage the dynamic credentials of users in a system. Many different RHIBE schemes were proposed previously, but they are not efficient in terms of the private key size and the update key size since the depth of a hierarchical identity is included as a multiplicative factor. In this paper, we propose efficient RHIBE schemes with shorter private keys and update keys and small public parameters by removing this multiplicative factor. To achieve our goals, we first present a new HIBE scheme with the different generation of private keys such that a private key can be simply derived from a short intermediate private key. Next, we show that two efficient RHIBE schemes can be built by combining our HIBE scheme, an IBE scheme, and a tree based broadcast encryption scheme in a modular way.

Unbounded Anonymous Hierarchical Identity-Based Encryption in the Standard Model

In this work, we present a new anonymous HIBE scheme which is unbounded in the sense that the public parameters do not impose additional limitations on the functionality of the systems. In most of previous constructions of anonymous HIBE in the standard model, a maximum hierarchy depth had to be fixed at setup. Our constructions avoid these limitations. We use a nested dual system encryption argument to prove full security for our anonymous HIBE scheme, in the standard model and relying on static assumptions.

Realizing Fully Secure Unrestricted ID-Based Ring Signature in the Standard Model Based on HIBE

We describe a secure and unrestricted identity-based ring signature scheme in the standard model. Our construction is provably fully secure in the standard model under static assumptions and is motivated by an existing HIBE scheme. Our observation on the relationship between ID-based ring signatures and HIBE is of interest to researchers in other fields as well. Following the strongest anonymity definition in ring signatures, we define a new level of anonymity for ID-based ring signatures in which the attacker can specify the randomness used in the creation of the user secret key, in addition to the private key generators master key. Our scheme provides unconditional anonymity in this model.

Practical hybrid (hierarchical) identity-based encryption schemes based on the decisional bilinear Diffie-Hellman assumption

The paper proposes a HIBE scheme, which improves upon Waters' scheme from Eurocrypt 2005 by significantly reducing the size of the public parameters. The improvement is based on two ideas: 1 partitioning the identities in smaller blocks; 2 reusing public parameters. Modification of the basic HIBE scheme yields a CCA-secure hybrid HIBE where symmetric key authentication is used to eliminate costly pairing operations from the decryption algorithm. The protocols and the security arguments are recast in the most efficient asymmetric pairing setting where one gets several variants of the basic protocol with associated trade-offs in the ciphertext overhead and public parameter size. For practical security levels, the variants we obtain are currently the most efficient and practical among all other schemes which achieve similar security under the DBDH assumption. The basic idea provides improvements to the construction of other cryptographic primitives such as signatures, wildcard IBE and certificateless encryption.

Anonymous HIBE Scheme Secure Against Full Adaptive-ID Attacks

This paper constructs a new anonymous IBE scheme,and expands it to an anonymous HIBE scheme secure against full adaptive-ID attacks.These systems are built in composite order groups,which have four prime order subgroups.To achieve the anonymity,the authors blinded the public parameters and ciphertexts using the random elements of same subgroup.Moreover,the authors used the random elements of different subgroup to construct secret key for properly decryption.This idea is inspired by the related work,which proposed by Seo et al.in PKC 2009.To obtain full security,the authors applied the new techniques for dual system encryption recently introduced by Lewko and Waters in TCC 2010.Like the techniques used in their paper,the authors also used the semi-functional structures,and employed a hyhrid argument in the security by a sequence of games proof.And employed an additional dummy semi-functional structure to overcome the difficulty in the proof of the anonymity.The new anonymous HIBE scheme has short ciphertexts,and can be proven to be secure in the full-ID model using static assumptions.However,the previous schemes were only proven in the selective-ID model,under some non-static assumption which depended on the depth of the hierarchy.

Anonymous Hierarchical Identity-Based Encryption with Short Ciphertexts

We propose an anonymous Hierarchical Identity-Based Encryption (anonymous HIBE) scheme with short ciphertexts. Prior to our work, most anonymous HIBE schemes have long ciphertexts increased according to the hierarchical depth of recipient. The size of the ciphertext in our scheme does not depend on the depth of the hierarchy. Moreover, our scheme achieves the lowest computational cost because during the decryption phase the computational cost of decryption is constant. The security can be proven under reasonable assumptions without using random oracles. Our scheme achieves selective-ID security notion.

Cryptanalysis of Two Efficient HIBE Schemes in the Standard Model

In Informatica 32 (2008), Ren and Gu proposed an anonymous hierarchical identity based encryption scheme based on the q-ABDHE problem with full security in the standard model. Later in Indocrypt'08, they proposed another secure hierarchical identity based encryption scheme based on the q-TBDHE problem with full security in the standard model. They claimed that their schemes have short parameters, high efficiency and tight reduction. However, in this paper we give attacks to show their schemes are not secure at all. Concretely, from any first level private key, the adversary can easily derive a “private key” which can decrypt any ciphertexts for the target identity. That is to say, a query on any first level identity is enough to decrypt any ciphertext in the system.

New Identity-Based Blind Signature and Blind Decryption Scheme in the Standard Model

We explicitly describe and analyse blind hierachical identity-based encryption (blind HIBE) schemes, which are natural generalizations of blind IBE schemes [20]. We then uses the blind HIBE schemes to construct: (1) An identity-based blind signature scheme secure in the standard model, under the computational Diffie-Hellman (CDH) assumption, and with much shorter signature size and lesser communication cost, compared to existing proposals. (2) A new mechanism supporting a user to buy digital information over the Internet without revealing what he/she has bought, while protecting the providers from cheating users.