Secret Key Size Research Articles

Novel Leakage-Resilient Attribute-Based Encryption from Hash Proof System

As an important primitive, attribute-based encryption (ABE) has attracted much attention in the relative-leakage model. However, the leakage rate in almost all of the existing ABE schemes is restricted with a leakage parameter. It implicitly suggests that higher leakage rate results in larger ciphertexts and keys. Aiming at tackling the challenge, novel leakage-resilient ciphertext-policy attribute-based encryption (CP-ABE) and key-policy attribute-based encryption (KP-ABE) are designed in this paper. It achieves shorter secret key size and simultaneously does not suffer from the undesirable drawback above. To realize this, the concepts of CP-AB-HPS and KP-AB-HPS are introduced, which generalize the notion of hash proof system (HPS) to attribute-based setting. Under some static assumptions, the proposed schemes are proved adaptively secure in the standard model. In addition, the results in simulation experiments indicate that the proposed scheme is efficient and practical.

Efficient attribute-based signature and signcryption realizing expressive access structures

This paper addresses the open problem of designing attribute-based signature (ABS) schemes with constant number of bilinear pairing operations for signature verification or short signatures for more general policies posed by Gagne et al. in Pairing 2012. Designing constant-size ABS for expressive access structures is a challenging task. We design two key-policy ABS schemes with constant-size signature for expressive linear secret-sharing scheme (LSSS)-realizable monotone access structures. Both the schemes utilize only 3 pairing operations in signature verification process. The first scheme is small universe construction, while the second scheme supports large universes of attributes. The signing key is computed according to LSSS-realizable access structure over signer's attributes, and the message is signed with an attribute set satisfying the access structure. Our ABS schemes provide the existential unforgeability in selective attribute set security model and preserve signer privacy. We also propose a new attribute-based signcryption (ABSC) scheme for LSSS-realizable access structures utilizing only 6 pairings and making the ciphertext size constant. Our scheme is significantly more efficient than existing ABSC schemes. While the secret key (signing key or decryption key) size increases by a factor of number of attributes used in the system, the number of pairing evaluations is reduced to constant. Our protocol achieves (a) ciphertext indistinguishability under adaptive chosen ciphertext attacks assuming the hardness of decisional Bilinear Diffie---Hellman Exponent problem and (b) existential unforgeability under adaptive chosen message attack assuming the hardness of computational Diffie---Hellman Exponent problem. The security proofs are in selective attribute set security model without using any random oracle heuristic. In addition, our ABSC achieves public verifiability of the ciphertext, enabling any party to verify the integrity and validity of the ciphertext.

Finger Knuckle Print as Unimodal Fuzzy Vault Implementation

A biometric template is a digital reference of distinct characteristics that are extracted from a biometric sample. The feature set obtained during enrollment is stored in the system database as a template.Disparate passwords, when biometric templates are compromised, it is not feasible for a valid user to rescind his biometric identifiers and change to another set of uncompromised identifiers. Due to this irrevocable nature of biometric data, attacks against the stored templates constitute a major security and privacy peril in a biometric system. The primary aim of this paper is to propose a novel technique for security of templates by using fuzzy vault implementation. The first proposed approach is used to extract the feature point from finger knuckle print (FKP). This approach uses an image processing techniques to extract the biometric feature from the user's finger knuckle print.The second approach is one of unimodal fuzzy vault implementation. Fuzzy vault is a cryptographic framework that binds the biometric template with a uniformly random key to build a secure sketch of the template. Only the secure sketch is stored and if the original template is uniformly random, it is not feasible to retrieve either the template or the key without any knowledge of the user's biometric data.The performances of the proposed approaches are evaluated using the experimental observation. The simplicity and efficiency of the proposed methods make it readily applicable in various security fields. The performance of the proposed fuzzy vault implementation has been evaluated for Hong Kong polytechnic university FKP database. In this fuzzy vault implementation for biometric evaluation the performance metrics used are Failure-to-Capture Rate (FTCR), Genuine Accept Rate (GAR) and False Accept Rate (FAR)Performance analysis is carried out in two phases. In the initial phase, the secret key size is varied and the results are obtained. In phase two, the effect of adding salt and pepper noise is considered. Noise is added to analyze the strength of the fuzzy vault implementation.

Attribute-Based Encryption for circuits on lattices

In the previous construction of attributed-based encryption for circuits on lattices, the secret key size was exponential to the number of AND gates of the circuit. Therefore, it was suitable for the shallow circuits whose depth is bounded. For decreasing the key size of previous scheme, combining the techniques of Two-to-One Recoding (TOR), and sampling on lattices, we propose a new Key-Policy Attribute-Based Encryption (KP-ABE) scheme for circuits of any arbitrary polynomial on lattices, and prove that the scheme is secure against chosen plaintext attack in the selective model under the Learning With Errors (LWE) assumptions. In our scheme, the key size is proportional to the number of gates or wires in the circuits.

Efficient forward secure identity-based shorter signature from lattice

We propose an efficient forward secure identity-based signature scheme from lattice assumption.The signing secret key size and the signature length of our scheme are much shorter and invariant.We p...

이진트리 기반의 속성기반 암호전송 알고리즘

In this paper, we present two constructions of the attribute-based broadcast encryption(ABBE) algorithm. Attribute-based encryption(ABE) algorithm enables an access control mechanism over encrypted data by specifying access policies among private keys and ciphertexts. ABBE algorithm can be used to construct ABE algorithm with revocation mechanism. Revocation has a useful property that revocation can be done without affecting any non-revoked uers. The main difference between our algorithm and the classical ones derived from the complete subtree paradigm which is apt for military hierarchy. Our algorithm improve the efficiency from the previously best ABBE algorithm, in particular, our algorithm allows one to select or revoke users by sending ciphertext of constant size with respect to the number of attributes and by storing logarithm secret key size of the number of users. Therefore, our algorithm can be an option to applications where computation cost is a top priority and can be applied to military technologies in the near future.

A Lattice-Based Identity-Based Proxy Blind Signature Scheme in the Standard Model

A proxy blind signature scheme is a special form of blind signature which allowed a designated person called proxy signer to sign on behalf of original signers without knowing the content of the message. It combines the advantages of proxy signature and blind signature. Up to date, most proxy blind signature schemes rely on hard number theory problems, discrete logarithm, and bilinear pairings. Unfortunately, the above underlying number theory problems will be solvable in the postquantum era. Lattice-based cryptography is enjoying great interest these days, due to implementation simplicity and provable security reductions. Moreover, lattice-based cryptography is believed to be hard even for quantum computers. In this paper, we present a new identity-based proxy blind signature scheme from lattices without random oracles. The new scheme is proven to be strongly unforgeable under the standard hardness assumption of the short integer solution problem (SIS) and the inhomogeneous small integer solution problem (ISIS). Furthermore, the secret key size and the signature length of our scheme are invariant and much shorter than those of the previous lattice-based proxy blind signature schemes. To the best of our knowledge, our construction is the first short lattice-based identity-based proxy blind signature scheme in the standard model.

Security of Multivariate Signature Scheme Using Non-commutative Rings

Multivariate Public Key Cryptosystems (MPKC) are candidates for post-quantum cryptography. Rainbow is a digital signature scheme in MPKC, whose signature generation and verification are relatively efficient. However, the security of MPKC depends on the difficulty in solving a system of multivariate polynomials, and the key length of MPKC becomes substantially large compared with that of RSA cryptosystems for the same level of security. The size of the secret and public keys in MPKC has been reduced in previous research. The NC-Rainbow is a signature scheme in MPKC, which was proposed in order to reduce the size of secret key of Rainbow. So far, several attacks against NC-Rainbow have been proposed. In this paper, we summarize attacks against NC-Rainbow, containing attacks against the original Rainbow, and analyze the total security of NC-Rainbow. Based on the cryptanalysis, we estimate the security parameter of NC-Rainbow at the several security level.

Efficient forward secure identity-based shorter signature from lattice

All regular cryptographic schemes rely on the security of the secret key. However, with the explosive use of some relatively insecure mobile devices, the key exposure problem has become more aggravated. In this paper, we propose an efficient forward secure identity-based signature (FSIBS) scheme from lattice assumption, with its security based on the small integer solution problem (SIS) in the random oracle model. Our scheme can guarantee the unforgeability of the past signatures even if the current signing secret key is revealed. Moreover, the signature size and the secret key size of our scheme are unchanged and much shorter. To the best of our knowledge, our construction is the first FSIBS scheme based on lattice which can resist quantum attack. Furthermore, we extend our FSIBS scheme to a forward secure identity-based signature scheme in the standard model.

Efficient hierarchical identity-based signatures from lattices

Lattice-based hierarchical identity-based signature HIBS schemes are receiving significant attention due to provable security reductions and potential security for quantum computers. However, most of the existing HIBS schemes based on lattices are less efficient for practical applications. To make lattice-based HIBS schemes become more practical, this paper presents an efficient HIBS scheme from lattices. Both the secret key size and the signature length of our proposal are much shorter than those of other lattice-based HIBS proposals. Our scheme is proven to be strongly unforgeable against adaptive identity attacks in the random oracle model. The security of the construction relies on the standard short integer solution SIS assumption.

Fully Secure Ciphertext-Policy Attribute-Based Encryption in Prime Order Group

We present a fully secure ciphertext-policy attribute-based encryption (CP-ABE) scheme in prime order group by using a tool which can convert composite order paring-based encryption scheme into prime order one. Although, a fully secure CP-ABE scheme in prime order group has been proposed recently, our scheme needs less master secret key size and can be seen as a different version of it. Besides, the sketch of our scheme's security proof is also given.

Efficient secure channel coding based on quasi-cyclic low-density parity-check codes

A secure channel coding (joint encryption-channel coding) scheme provides both data security and reliability in one combined process to achieve faster processing and/or more efficient implementation. The issue of using quasi-cyclic low-density parity-check (QC-LDPC) codes in a symmetric-key secure channel coding scheme is addressed. A set of this class of LDPC codes has recently been recommended by the NASA Goddard Space Flight Center for near-earth and deep-space communications. The proposed scheme provides an efficient error performance, an acceptable level of security and a low-complexity practicable implementation. The results indicate that the proposed scheme can efficiently employ large QC-LDPC codes to achieve a relatively smaller secret-key size to be exchanged by the sender and the receiver, and higher information rates in comparison with the previous symmetric-key McEliece-like schemes. Simulation results indicate that there is no trade-off between the error performance and the security level of the proposed scheme unlike that of the previous ones. These characteristics make the proposed scheme suitable for high-speed communications, such as satellite communication systems.

On vulnerabilities and improvements of fast encryption algorithm for multimedia FEA-M

FEA-M is evaluated from cryptographic security of view and the weaknesses of its algebraic structure are pointed out which imply that the effective secret key size, under realistic known and chose plaintext attacks, is much smaller than its nominal one. Particularly, existence of a large class of the weak keys is shown. It appears that FEA-M is an insecure algorithm even if secret keys of 4096 bits are employed. On the other hand, it is shown that FEA-M is very sensitive on the packet loss errors. Finally, am improved variant of FEA-M is proposed which is resistant against the developed attacks, as well as to the packet loss errors.

Controlling access in tree hierarchies

Inspired from Sandhu's scheme, this paper presents a cryptographic key assignment scheme in tree hierarchies for access control. Initially, the root security class is assigned an arbitrary secret key which is a 3-dimensional row vector. Any other security class's secret key can be generated or derived from its ancestor's secret key as needed. In our scheme, the secret key can be used directly as an encryption key, or used as an encryption-encryption key for generating an encryption key to encipher the owned information items. Our scheme preserves the advantages of Sandhu's scheme, such as a new security class can be defined easily and the size of secret key is fixed. Furthermore, each security class can freely choose or change its encryption key for protecting the owned information items without altering the existing secret keys.