针对目前密码科学与技术专业人才培养体系存在的"能力指向不够清晰、实践特色不够突出"问题,深层剖析网络密码时代密码学人才培养的核心目标和关键指标,提出"理念—体系—课程—平台"四位一体的改革模式,介绍如何构建密码科学与技术专业本科专业人才KSA能力体系,搭建密码科学与技术专业实践教学基础训练平台,以实现高质量的密码人才供给输送,全面提升密码科学与技术专业人才培养的科学性和实用性.

针对密码学课程存在"重理论轻实践,重编码轻分析"的教学现状,剖析密码分析实践类课程的难点,提出将具有攻防对抗特色的CTF(Capture The Flag,夺旗竞赛)模式引入密码分析实践课程中,并从课程思政、考核评价等方面探讨如何进行探索创新,最后通过实践结果分析,说明该模式能够进一步激发学生的主动性和创造性.

Identity-based broadcast encryption (IBBE) is an effective method to protect the data security and privacy in multi-receiver scenarios, which can make broadcast encryption more practical. This paper further expands the study of scalable revocation methodology in the setting of IBBE, where a key authority releases a key update material periodically in such a way that only non-revoked users can update their decryption keys. Following the binary tree data structure approach, a concrete instantiation of revocable IBBE scheme is proposed using asymmetric pairings of prime order bilinear groups. Moreover, this scheme can withstand decryption key exposure, which is proven to be semi-adaptively secure under chosen plaintext attacks in the standard model by reduction to static complexity assumptions. In particular, the proposed scheme is very efficient both in terms of computation costs and communication bandwidth, as the ciphertext size is constant, regardless of the number of recipients. To demonstrate the practicality, it is further implemented in Charm, a framework for rapid prototyping of cryptographic primitives.

In this paper, we introduce a new multi-authority ciphertext policy attribute-based encryption (MA-CP-ABE) system. In our system, there are multiple central authorities (CAs) and attribute authorities (AAs). The CAs will not need to coordinate or even be aware of each other, and so do the AAs. In particular, we present two constructions that will be proved secure in the standard model. Our first scheme is fully secure under static assumptions in composite-order bilinear group, and can work for any monotone access structure. The second one achieves constant size ciphertexts for AND-gate policy in prime-order group. The security can be proved under the decisional linear (DLIN) assumption.

Secure and efficient authentication protocols are necessary for cloud service. Multi-factor authentication protocols taking advantage of smart card, user's password and biometric, are more secure than password-based single-factor authentication protocols which are widely used in practice. However, almost all the existed two-factor authentication protocols and multi-factor authentication protocols are based on smart cards, which will inevitably lead to a series of security problems caused by the loss of smart cards. Recently, Li et al. proposed a two-factor authenticated key agreement protocol based on biometric feature and password innovatively without using smart card. But we demonstrate that Li et al.'s protocol can't resist the privileged-insider attack and the stolen verifier attack. Moreover, their protocol failed to provide user anonymity. To overcome the weaknesses of Li et al.' s scheme, we then proposed an improved two-factor authentication protocol based on the extended Chebyshev chaotic mapping. To illustrate the security of our scheme, we give a standard formal proof with the sequence of games (SOG) technique. Furthermore, we also present a comprehensive heuristic security analysis to demonstrate that the proposed protocol is capable of withstanding all the possible various attacks and provides the desired security features. Compared with other schemes, ours is more secure and efficient.

Recently, leakage-resilient cryptography has become a hot research topic. It seeks to build more robust models of adversarial access to cryptographic algorithms. The main goal is to design a scheme that remains secure even when arbitrary, yet bounded, information about secret key is leaked. In this paper, we present a modular framework for designing leakage-resilient attribute-based encryption (ABE) schemes based on extended predicate encoding. We first extend the predicate encoding to the leakage-resilient predicate encoding; and then, design several leakage-resilient predicate encodings, and finally give a generic construction of leakage-resilient ABE based on the newly proposed encodings. Moreover, we can instantiate our framework in prime order bilinear groups to obtain concrete constructions, and prove their full security under the standard k-Lin assumption in the continual memory leakage model.

Decentralized attribute-based encryption (ABE) is a special form of multiauthority ABE systems, in which no central authority and global coordination are required other than creating the common reference parameters. In this paper, we propose a new decentralized ABE in prime-order groups by using extended dual system groups. We formulate some assumptions used to prove the security of our scheme. Our proposed scheme is fully secure under the standard k-Lin assumption in randomoraclemodel and can support any monotone access structures. Compared with existing fully secure decentralized ABE systems, our construction has shorter ciphertexts and secret keys. Moreover, fast decryption is achieved in our system, in which ciphertexts can be decrypted with a constant number of pairings.

Ciphertext-policy attribute-based encryption(CP-ABE) has become a crucial technical for cloud computing in that it enables one to share data with users under the access policy defined by himself. Generally, the universe of attributes is not fixed before the system setup in practice. So in this paper, we propose a CP-ABE scheme with large attribute universe based on the scheme presented by Chen et al. The number of attributes is independent of the public parameter in our scheme, and it inherents the excellent properties of both constant ciphertext and constant computation cost.

Based on prime‐order bilinear groups ,we propose a decentralized multi‐authority attribute‐based encryption scheme which is proven to be secure in the standard model .Firstly ,we construct an attribute‐based encryption system with a central authority (CA ) and multiple attribute authorities (AAs) ,where CA is responsible for generating a random value associated with each user’s unique global identifier (GID) ,and does not participate in any operation related to users’ attributes .Different users will get different random values ,thus they cannot obtain any information beyond authority even through collusion .Every attribute authority is responsible for different attributes domain and they are independent of each other .It’s even not necessary to know the existence of each other in the system . In particular ,there is no authority that can decrypt a ciphertext alone .Secondly ,this scheme can be extended to a decentralized attribute‐based encryption with multiple CAs setting ,where every CA is also independent of each other ,and each user can issue his private key from only one CA .Bringing it into practice under the Charm infrastructure ,the results show that the decentralized attribute based encryption schemes are very efficient ,whose ciphertexts are of constant size ,i .e .,regardless of the number of underlying attributes of access control policy or users .

This paper present an identity-based encryption (IBE) scheme with full security in prime order bilinear groups by using dual pairing vector space. The security of our scheme is based upon decisional linear and three party Diffie-Hellman assumption by adapting the dual system encryption. We obtain a tighter security reduction compared to previous works based on dual system encryption. The loss for security reduction of our scheme is 𝒪(q_1) , where q_1 is the number of key queries in Phase 1.

Asymmetric searchable encryption(ASE) enables one to retrieve encrypted data stored on an untrusted server without revealing the contents. Now, beyond single keyword search, more and more attention have already been paid to the problem of multi-keyword search. However, existing schemes are mainly based on composite-order bilinear groups. In this paper, we propose a public key encryption with conjunctive and disjunctive keyword search(PECDK) scheme which can simultaneously support conjunction and disjunction within each keyword field for cloud storage. It is based on prime-order bilinear groups, and can be proved fully secure under the standard model.

Three-party password authenticated key exchange (3PAKE) protocols allow two clients to establish a common secure session key via the help of an authentication server, in which each client only needs to share a single password with the server. Many researchers pay attention to 3PAKE protocols since they are well suited for large-scale communication in mobile environments. Recently, Farash et al. proposed an enhanced 3PAKE protocol without using server's public-keys and symmetric cryptosystems. They claimed that their protocol is secure against various attacks. However, we found that Farash et al.'s protocol is vulnerable to partition attacks and off-line dictionary attacks. Moreover, their protocol needs 5 rounds to work, so it is inefficient in terms of communication. To overcome these shortcomings, we improve their protocol and propose a provably secure 3PAKE protocol, which is more efficient and secure than other related protocols.DOI: http://dx.doi.org/10.5755/j01.itc.44.2.8197

In this paper, we present a new construction of attribute-based signature (ABS) scheme supporting flexible threshold predicates from lattices. The new construction is proved to be selective-predicate and adaptive-message unforgeable under chosen message attacks in random oracle model if the small integer solution (SIS) assumption holds. In addition, this scheme can also achieve privacy, which means the signature reveals nothing about the attributes or identity information about the real signer. Compared with existing lattice-based threshold ABS scheme, the new construction provides better efficiency.

Inner product encryption (IPE) is a concrete construction of predicate encryption ,which represents a wide class of predicates that includes an equality test (for identity‐based encryption and hidden vector encryption ) , disjunctions or conjunctions of equality tests ( for attribute‐based encryption) .Hierarchical inner product encryption (HIPE) can provide the capacity of delegate for inner product encryption ,and it can effectively reduce the workload of root node of the system . Aiming at the efficiency that exists in the hierarchical inner product encryption ,we present a short ciphertexts IPE scheme with full security in asymmetric bilinear pairing .By making use of the IPE scheme as building blocks ,we then present a new HIPE scheme with the new technique for dual system encryption .The new realization of dual system encryption does not use tags ,which makes the compression of ciphertexts possible .The proposed HIPE scheme achieves constant‐size ciphertexts and full security in the standard model .Security is proven under three static assumptions w hose size does not depend on the number of queries .Furthermore ,our scheme achieves lower computational cost because decryption only needs seven pairing operations .Compared with other existing schemes , our scheme is more compact to implement and can provide better efficiency in terms of the communication and computation cost .

Fuzzy identity-based encryption can provide an error-tolerance property for identity-based systems ,and it allows a sender to encrypt a message to all users who have a certain set of attributes .In this paper ,we proposed a fuzzy identity-based en-cryption scheme with constant size of ciphertexts that is indistinguishable against adaptive chosen ciphertexts attacks (CCA2 )in the standard model .Compared with other existing schemes ,this construction can satisfy the application requirements ,as it can provide better efficiency in terms of the communication and computation cost as well as a stronger security guarantee .

In a decentralized attribute-based encryption (ABE) system, any party can act as an authority by creating a public key and issuing private keys to different users that reflect their attributes without any collaboration. Such an ABE scheme can eliminate the burden of heavy communication and collaborative computation in the setup phase of multiauthority ABE schemes, thus is considered more preferable. Recently in IEEE Transactions Parallel Distributed Systems, Han et al. proposed an interesting privacy-preserving decentralized key-policy ABE scheme, which was claimed to achieve better privacy for users and to be provably secure in the standard model. However, after carefully revisiting the scheme, we conclude that their scheme cannot resist the collusion attacks, hence fails to meet the basic security definitions of the ABE system.

Recently, Wang et al. presented a new construction of attribute-based signature with policy-and-endorsement mechanism. The existential unforgeability of their scheme was claimed to be based on the strong Diffie-Hellman assumption in the random oracle model. Unfortunately, by carefully revisiting the design and security proof of Wang et al.’s scheme, we show that their scheme cannot provide unforgeability, namely, a forger, whose attributes do not satisfy a given signing predicate, can also generate valid signatures. We also point out the flaws in Wang et al.’s proof.

In PKC 2010, Herranz et al. proposed the first ciphertext policy attribute-based encryption (CP-ABE) scheme with constant size ciphertexts for threshold predicates. However, their scheme was only secure against chosen plaintext attacks (CPA), which was impossible to obtain security against chosen ciphertext attacks (CCA) in the standard model, and they left open the following three problems for CP-ABE schemes with constant size ciphertexts, i.e., how to achieve full security (i.e., not only the selective security), CCA security in the standard model, and security reduction to a more standard mathematical problem. In this paper, we answer the last two of these three problems affirmatively. Towards our goal, we first design a CPA secure threshold CP-ABE scheme, which can be further upgraded to the CCA security. The security of our schemes can be proved under the decisional q-Bilinear Diffie-Hellman Exponent (q-BDHE) assumption in the selective model. To the best of our knowledge, this is the first construction of CCA secure CP-ABE scheme with constant size ciphertexts that can support flexible threshold access structure in the standard model.