The widespread adoption of Transformer models raises critical privacy concerns as users must expose sensitive inputs to service providers during inference. While existing secure Transformer frameworks have addressed this issue to some extent, most rely on interactive protocols with prohibitive communication overhead, limiting practicality in bandwidth-constrained scenarios. This paper introduces Zephyr, a secure and non-interactive two-party inference framework for Transformers that overcomes these limitations. First, Zephyr proposes two novel SIMD ciphertext decompression techniques, shifting from serial to parallel processing to accelerate decompression by 1.2× while preserving accuracy. Second, Zephyr optimizes the deployment strategy of bootstrapping operations (which refresh encrypted data noise) during computation. This allows using smaller encryption parameters while achieving 1.1× faster bootstrapping than NEXUS. Evaluated on BERT-base under challenging 100Mbps/80ms conditions, Zephyr demonstrates superior performance - 24.3× faster than Iron(NeurIPS22), 2.1× faster than BOLT, and 11% faster than NEXUS while reducing communication costs by 95% versus BOLT(Oakland24) and 32% versus NEXUS(NDSS25), making it particularly effective for bandwidth-constrained environments while maintaining security against semi-honest adversaries.

With the increasing demand of consumers for food safety, the application of Internet of Things (IoT) in agriculture is more and more extensive, especially the use of technologies such as QR codes and sensors for food information traceability. However, the Internet of Things still faces challenges in ensuring the authenticity of food data transmission and the integrity of food anti-counterfeiting authentication, especially the traditional digital signature algorithm that the Internet of Things relies on is vulnerable to the security threat brought by future quantum computers. In order to solve this problem, we propose a domestic replacement solution for the post-quantum digital signature algorithm SPHINCS-α(an improvement of the standardized post-quantum digital signature scheme SPHINCS+), and use the chinese national standard cryptographic hash function Shang Mi 3 (SM3) to replace its underlying hash function. Finally, we conducted experiments, gave the benchmark test results under three security parameters, and compared the performance with the original scheme using SHA256 and Shake256 hash function. The results prove the feasibility of our method, although there is a small rate drop, but in exchange for a more secure domestic hash function. It provides strong support for the early deployment of post-quantum cryptography algorithm in the Internet of Things environment of sustainable agriculture and industry, and ensures the integrity of the Internet of Things data in the practice of sustainable agriculture.

Abstract Video steganography has the potential to be used to convey illegal information, and video steganalysis is a vital tool to detect the presence of this illicit act. Currently, all the motion vector (MV)‐based video steganalysis algorithms extract feature sets directly from the MVs, but ignoring the embedding operation may perturb the statistical distribution of other video encoding elements, such as the skipped macroblocks (no direct MVs). This paper proposes a novel 11‐dimensional feature set to detect MV‐based video steganography based on the above observation. The proposed feature is extracted based on the skipped macroblocks by recompression calibration. Specifically, the feature consists of two components. The first is the probability distribution of motion vector prediction (MVP) difference, and the second is the probability distribution of partition state transfer. Extensive experiments on different conditions demonstrate that the proposed feature set achieves good detection accuracy, especially in lower embedding capacities. In addition, the loss of detection performance caused by recompression calibration using mismatched quantization parameters (QP) is within the acceptable range, so the proposed method can be used in practical scenarios.

Abstract Traditional video steganography methods primarily rely on modifying concealed spaces for embedding, thereby exhibiting a certain degree of security and embedding capacity. Nevertheless, these methods do not fully capitalize on the rich semantic information inherent in videos, limiting their overall effectiveness. In this paper, an AI‐generated video steganography scheme based on semantic segmentation is proposed. The mapping relationship between secret and semantic information is established by using a semantic segmentation model. The secret information can be converted into semantic labels by semantic histograms or pixels means, and semantic labels containing secret information are obtained and input into the video‐to‐video model to drive the generation of stego videos. After receiving the stego video, the receiver extracts the secret information using a pre‐defined specific embedding mode, including the methods of sub‐block partitioning and embedding capacity per frame. The experimental results show that the stego video has good visual quality, security, and robustness against various noise attacks.

Privacy-preserving multidimensional data aggregation aggregates the data of all different users into a single value, preventing the leakage of personal data while ensuring its availability. However, most current multidimensional data aggregation schemes only consider sum operations, i.e., the message of each dimension in the aggregation result is the sum of the corresponding dimensional messages of all individual message vectors. We propose a multidimensional data aggregation scheme with fine-grained linear homomorphism, called MDA-FLH. Firstly, we construct a fine-grained linear homomorphic encryption scheme which can assign different weights to each dimension of user’s data and maintain the linear homomorphic property in each dimension. We combine the Chinese remainder theorem and Paillier encryption to encode the multidimensional data with CRT and assign different weights to each dimension of user’s data in the Paillier ciphertext. Secondly, our scheme has the property of fault tolerance. In conjunction with extended Shamir’s threshold secret-sharing scheme, a security-enhanced and fault-tolerant data aggregation method has been designed so that it is resistant to internal attacks such as the control center (CC) access to individual private data if given the corresponding ciphertext. Finally, two practical schemes are designed based on MDA-FLH: fine-grained electricity price statistics scheme and multistep electricity price statistics scheme. Security analysis shows that our scheme can achieve privacy, confidentiality, integrity, and source authentication. Performance analysis shows that our scheme is efficient, especially that SMs are computationally economic, which makes our scheme more suitable for resource-constrained SM. Also, our scheme can provide linear homomorphism operations on each dimension, which further expands its applications.

With the rapid development of smart grids (SGs), designing a data aggregation scheme that ensures both data availability and privacy security has become an urgent necessity. Particularly, considering the potential failures of smart meters (SMs), ensuring fault tolerance in data decryption has become a significant challenge in the design. Recently, Wu et al. proposed a fault-tolerant data aggregation scheme FPDA that excels in privacy protection and fault tolerance. However, like most data aggregation schemes in SG, FPDA relies on a trust authority (TA), which is difficult to find in real-world scenarios. Furthermore, the scheme is vulnerable to delay attacks, posing a risk of individual meter privacy leakage. Therefore, this article first designs an attack for FPDA scheme which capable of achieving 100% plaintext recovery when users delays, with an attack time of only 518 ms. Subsequently, we propose a secure fault-tolerant and privacy-enhanced data aggregation scheme for SG without TA (SFPDA). By employing multiuser Diffie-Hellman key exchange (MDHKE), we eliminate the need for a trusted third party, Additionally, we utilize dual masking to resist delay attacks. We conduct a security analysis of the scheme, which demonstrates that SFPDA can resist delay attacks and provide enhanced privacy protection. Finally, experimental results show that SFPDA reduces encryption time by approximately 40% and decryption time by approximately 83.3%, while offering better fault tolerance, making it more suitable for grid environments where the number of residents remains constant, but the failure rate of meters fluctuates.

As the Internet of Things (IoT) is booming, the transmission speed of data in the network is getting more and more attention. Network coding is an effective technique to improve network throughput. In network coding, the encoded packets must be integrity-checked to prevent pollution attacks. Some linearly homomorphic signature (LHS) schemes based on bilinear pairs have been used to check the integrity of packets, and so far the scheme LZL20 is the most efficient signature scheme among them. Here, we first analyze the security model and signature structure of LZL20, and find that there is a security vulnerability in the scheme. Experiments show that for a 12–18 kB file, our signature forgery algorithm can forge a message/signature pair with 100% probability within 3–5 ms. Then, we construct a LHS scheme with higher signature efficiency and shorter signature length. In random oracle model, we proved the scheme is existentially unforgeable under adaptive chosen message attacks. We theoretically analyze our signature length to be 320 bits shorter than LZL20. Finally, we implement our scheme, and for a 12–18 kB file, experiments show that the signature time of our scheme is 60.93%–62.59% of that of LZL20.

Privacy protection of biometrics-based on cloud computing is attracting increasing attention. In 2018, Zhuet al.proposed an efficient and privacy-preserving online fingerprint authentication scheme for data outsourcing e-Finga. Under the premise of ensuring user's fingerprint data privacy and message security authentication, the e-Finga scheme can provide accurate and efficient fingerprint identity authentication services. However, our analysis shows that the temporary fingerprint in this scheme uses the deterministic encryption algorithm, which has the risk of leaking the user's fingerprint characteristics. Therefore, we propose a temporary fingerprint attack method for the e-Finga scheme. Experiments demonstrate that an adversary can analyze specific secret parameters and fingerprint features when eavesdropping on a user's temporary fingerprint ciphertext. To counter the temporary fingerprint attack, we propose a secure e-fingerprint scheme– Secure e-finger that uses the learning with errors samples, which has the homomorphic addition property, to encrypt user's temporary fingerprints. Experiments show that the secure e-finger scheme can resist the temporary fingerprint attack. Compared with the unprotected e-Finga scheme, the client running time is increased by about 6% percent, the communication cost on the user side only increased by 0.3125% percent. As a result, our solution can realize secure online fingerprint authentication without losing efficiency. Single user authentication is likely to cause the problem of excessive authority. Based on the Secure e-finger scheme, we propose a threshold scheme based on biological characteristics.

Biometric technologies are being prominently used everywhere. However, the leakage of biometric information can pose a serious security risk, making the protection of biometric templates particularly important and receiving more attention. Rathgeb et al. first proposed the cancelable biometric technology based on Bloom filters in 2013, which has been applied to protect different biometric templates. Bloom filter-based biometrics offer the advantages of alignment-free, fast recognition and high accuracy. An ideal biometric system should also be irreversibility and unlinkability. In this paper, firstly, we propose a reverse reconstruction attack. Through the reverse reconstruction of Bloom filters, we find that the reconstructed biometric data and the original biometric data have some strong statistical correlation, which proves that the scheme has the linkability defect. Experiments show that for the original Bloom filter-based biometric template protection scheme, we can judge whether two different biometric templates belong to the same user with a success probability of 71.0%. Secondly, to remedy above defect, we construct a structure-preserving encryption scheme, i.e., the feature template encrypted with it maintains the structure and length of the original template, making it impossible for an attacker to reconstruct meaningful data from Bloom filter. Finally, an improved biometric template protection scheme based on Bloom filters is proposed by introducing the proposed encryption. Attack experiment shows that the improved scheme can effectively resist the reverse reconstruction attack, with the success probability of attacking the unlinkability of the improved scheme being 50.0%, which is the same as the probability of random guessing. Performance evaluation shows that the proposed scheme maintains the biometric performance of the original system and the unprotected system.

Threshold proxy re-encryption (TPRE) can prevent collusion between a single proxy and a delegatee from converting arbitrary files against the wishes of the delegator through multiple proxies, and can also provide normal services even when certain proxy servers are paralyzed or damaged. A non-interactive identity-based TPRE (IB-TPRE) scheme over lattices is proposed which removes the public key certificates. To accomplish this scheme, Shamir’s secret sharing is employed twice, which not only effectively hides the delegator’s private key information, but also decentralizes the proxy power by splitting the re-encryption key. Robustness means that a combiner can detect a misbehaving proxy server that has sent an invalid transformed ciphertext share. This property is achieved by lattice-based fully homomorphic signatures. As a result, the whole scheme is thoroughly capable of resisting quantum attacks even when they are available. The security of the proposed scheme is based on the decisional learning with error hardness assumption in the standard model. Two typical application scenarios, including a file-sharing system based on a blockchain network and a robust key escrow system with threshold cryptography, are presented.

Schemes of reversible data hiding in encrypted domain (RDH-ED) based on symmetric or public key encryption are mainly applied in the scenarios of end-to-end communication. To provide security guarantees for the multi-party scenarios, a RDH-ED scheme for secret image sharing based on Chinese remainder theorem (CRT) is presented. In the application of ($t$,$n$) secret image sharing, an image is first shared into$n$different shares of ciphertext. Only when not less than$t$shares obtained, can the image be reconstructed. In our scheme, additional data could be embedded into the image shares. To realize data extraction from the image shares and the reconstructed image separably, two data hiding methods are proposed: one is homomorphic difference expansion in encrypted domain (HDE-ED) that supports data extraction from the reconstructed image by utilizing the addition homomorphism of CRT secret sharing; the other is difference expansion in image shares (DE-IS) that supports the data extraction from the marked shares before image reconstruction. Experimental results demonstrate that the proposed scheme could not only maintain the security and the threshold function of secret sharing system, but also obtain a better reversibility and efficiency compared with most existing RDH-ED algorithms. The maximum embedding rate of HDE-ED could reach 0.500 bits per pixel and the average embedding rate of DE-IS could reach 0.4652 bits per pixel.

Abstract Multi‐key fully homomorphic encryption (MKFHE) allows computations on ciphertexts encrypted by different users, which can be applied to implement secure multi‐party computing (MPC). The current NTRU‐based MKFHE has the following two drawbacks: One is that the relinearisation process during homomorphic evaluation is so complicated that the corresponding computation time is costly. The other is that a class of subfield attacks are proposed and affects the security of NTRU schemes over power‐of‐2 cyclotomic rings for large moduli q, especially for the NTRU‐based fully homomorphic encryption (FHE) schemes. In this work, an efficient MKFHE scheme is proposed over prime cyclotomic rings with fewer relinearisations, which seems a good choice because of its potential to resist a subfield attack. More specifically, the time of the relinearisation process is reduced by half in homomorphic evaluations by separating the homomorphic multiplication and the relinearisation process (implementing two homomorphic multiplication operations together before relinearisation), while in current NTRU‐type MKFHE schemes, these two processes are usually performed together. The error bound of the basic function components is re‐analysed over prime cyclotomic rings in the average case, which can be used in the error analysis of our scheme. We construct an efficient NTRU‐based single‐key FHE scheme and an efficient MKFHE scheme over prime cyclotomic rings through relinearisation and modulus‐switching techniques. The MKFHE scheme proposed has the on‐the‐fly property and has a tight ciphertext size compared with the GSW‐type and BGV‐type MKFHE schemes. An experiment shows that the homomorphic evaluation of the optimised single‐key FHE scheme proposed is 1.9 times faster than an efficient NTRU‐type MKFHE DHS16 proposed at DCC 2016.

Steganography is a technique for publicly transmitting secret information through a cover. Most of the existing steganography algorithms are based on modifying the cover image, generating a stego image that is very similar to the cover image but has different pixel values, or establishing a mapping relationship between the stego image and the secret message. Attackers will discover the existence of secret communications from these modifications or differences. In order to solve this problem, we propose a steganography algorithm ISTNet based on image style transfer, which can convert a cover image into another stego image with a completely different style. We have improved the decoder so that the secret image features can be fused with style features in a variety of sizes to improve the accuracy of secret image extraction. The algorithm has the functions of image steganography and image style transfer at the same time, and the images it generates are both stego images and stylized images. Attackers will pay more attention to the style transfer side of the algorithm, but it is difficult to find the steganography side. Experiments show that our algorithm effectively increases the steganography capacity from 0.06 bpp to 8 bpp, and the generated stylized images are not significantly different from the stylized images on the Internet.

With the advent of data outsourcing, how to efficiently verify the integrity of data stored at an untrusted cloud service provider (CSP) has become a significant problem in cloud storage. In 2019, Guo et al. proposed an outsourced dynamic provable data possession scheme with batch update for secure cloud storage. Although their scheme is very novel, we find that their proposal is not secure in this paper. The malicious cloud server has ability to forge the authentication labels, and thus it can forge or delete the user’s data but still provide a correct data possession proof. Based on the original protocol, we proposed an improved one for the auditing scheme, and our new protocol is effective yet resistant to attacks.

Now, it is common for patients and medical institutions to outsource their data to cloud storage. This can greatly reduce the burden of medical information management and storage and improve the efficiency of the entire medical industry. In some cases, the group‐based cloud storage system is also very common to be used. For example, in an medical enterprise, the employees outsource the working documents to the cloud storage and share them to the colleagues. However, when the working documents are outsourced to the cloud servers, how to ensure their security is a challenge problem for they are not controlled physically by the data owners. In particular, the integrity of the outsourced data should be guaranteed. And the secure cloud auditing protocol is designed to solve this issue. Recently, a lightweight secure auditing scheme for shared data in cloud storage is proposed. Unfortunately, we find this proposal not secure in this paper. It’s easy for the cloud server to forge the authentication label, and thus they can delete all the outsourced data when the cloud server still provide a correct data possession proof, which invalidates the security of the cloud audit protocol. On the basis of the original security auditing protocol, we provide an improved one for the shared data, roughly analysis its security, and the results show our new protocol is secure.

This paper proposes a fully homomorphic encryption encapsulated difference expansion (FHEE-DE) scheme for reversible data hiding in encrypted domain (RDH-ED). The homomorphic circuits and ciphertext operations are elaborated. Key-switching and bootstrapping techniques are introduced to control the ciphertext extension and decryption failure of homomorphic encryption. A key-switching based least-significant-bit (KS-LSB) data hiding method has been designed to realize data extraction directly from the encrypted domain without the private key. In application, the user first encrypts the plaintext and uploads ciphertext to the server. The server embeds additional data into the ciphertext by performing FHEE-DE data hiding and KS-LSB data hiding. Additional data can be extracted directly from the marked ciphertext by the server without the private key. The user owns the private key and can decrypt the marked ciphertext to obtain the marked plaintext. Then additional data or plaintext can be obtained from the marked plaintext by using the standard DE extraction or recovery. The server could also implement FHEE-DE recovery or extraction on the marked ciphertext to return the ciphertext of original plaintext or additional data to the user. Experimental results demonstrate that the embedding capacity and reversibility of the proposed scheme are superior to existing RDH-ED methods, and fully separability is achieved without reducing the security of encryption.

Nowadays, the location privacy problem has become an important problem for the users who enjoy the location-based services (LBSs). Researchers have focused on the problem of how to protect the location privacy of user efficiently for a long time. On one hand, many achievements adopt the centralized structure in which there is an additional center server. Additionally, some other researchers adopt the distributed structure to overcome the disadvantages brought by the center server in the centralized anonymous system structure. On the other hand, the existing methods of solving the problem are always to protect the individual user’s location privacy in LBSs, without considering the user group’s location privacy. This kind of methods is not very applicable to the status of a number of users who formed a group to complete a LBS task together by collaborative computing. In order to solve the problem of location privacy protection for a user group in the untrusted mobile social networks, a location privacy protection method based on the distributed structure is discussed in this paper. In the scheme, the special homomorphic features of BGN cryptosystem are cleverly used so that it can solve the group’s three classical location service applications simultaneously, namely, group nearest neighbor query, optimal group collection point determination, and group friend’s distance query, by only one security policy. If there are k users who formed the group, it could achieve k-anonymity without exposing the coordinate of each individual user or using any anonymous areas. Furthermore, theoretical and experimental analysis proves that the proposal can efficiently protect each user’s location privacy in the group through taking full advantage of the collaborative computing and communication capabilities of the mobile terminals. It can resist the existing distance interaction attack and collusion attack and can realize the secure and efficient fine-grained controllable location privacy protection for the user group.

Side-channel attacks on cryptographic chips in embedded systems have been attracting considerable interest from the field of information security in recent years. Many research studies have contributed to improve the side-channel attack efficiency, in which most of the works assume the noise of the encryption signal has a linear stable Gaussian distribution. However, their performances of noise reduction were moderate. Thus, in this paper, we describe a highly effective data-preprocessing technique for noise reduction based on empirical mode decomposition (EMD) and demonstrate its application for a side-channel attack. EMD is a time-frequency analysis method for nonlinear unstable signal processing, which requires no prior knowledge about the cryptographic chip. During the procedure of data preprocessing, the collected traces will be self-adaptably decomposed into sum of several intrinsic mode functions (IMF) based on their own characteristics. And then, meaningful IMF will be reorganized to reduce its noise and increase the efficiency of key recovering through correlation power analysis attack. This technique decreases the total number of traces for key recovering by 17.7%, compared to traditional attack methods, which is verified by attack efficiency analysis of the SM4 block cipher algorithm on the FPGA power consumption analysis platform.

Summary In the IoT setting, many resource constrained devices outsource their collected data to the Cloud. To ensure the outsourced data has not been lost, these devices need some mechanism to check the integrity of their data. Furthermore, in some settings, ad hoc devices need to act as a group, and in this group, any member may require to verify the integrity of outsourced cloud storage. Aiming at solving this problem, in AISACCS'15, first proposed the concept of group‐based proofs of storage (GPoS). In GPoS, a group manager can authorize data owners as group members, and then these group members can outsource files to the cloud storage server; later, each member can verify the integrity of the outsourced cloud storage. They also give a concrete construction of GPoS. Unfortunately, in this paper, we find their scheme is not secure. Recently, also proposed a dynamic group‐based integrity auditing protocol for outsrouced cloud storage; we also show their scheme is not secure either. Finally, we give an improved scheme and roughly analysis to its security and performance.

Summary Private set intersection (PSI) protocols enable 2 parties to compute the intersection of their inputs without compromising anything about the datasets beyond the intersection. With the advent of cloud computing, outsourcing computation has been attracted wide range of attention from research community and applied widely in the industry. The cloud computing allows resources restrained devices to outsource their expensive computation to the cloud. Based on Abadi's O‐PSI, we present a variant of delegated private set intersection protocol secure in the semi‐honest model under RSA assumption, and we also give an efficient and secure outsourcing computation algorithm for RSA cryptosystem. Depending on this algorithm, we transform a variant of delegated private set intersection protocol into an improved outsourced one. It enables the clients only to perform simple modular multiplication for computing what they want during the execution of protocol. Besides, the variant of delegated protocol can be easily extended to multiple clients. Compared with the state of the art, our proposed protocol has great advantage in efficiency. We finally evaluate these protocols and prove their security in the semi‐honest model.

The decline in genome sequencing costs has widened the population that can afford its cost and has also raised concerns about genetic privacy. Kim et al. present a practical solution to the scenario of secure searching of gene data on a semitrusted business cloud. However, there are three errors in their scheme. We have made three improvements to solve these three errors. (1) They truncate the variation encodings of gene to 21 bits, which causes LPCE error and more than 5% of the entries in the database cannot be queried integrally. We decompose these large encodings by 44 bits and deal with the components, respectively, to avoid LPCE error. (2) We abandon the hash function used in Kim’s scheme, which may cause HCE error with a probability of 2-22 and decompose the position encoding of gene into three parts with the basis 211 to avoid HCE error. (3) We analyze the relationship between the parameters and the CCE error and specify the condition that parameters need to satisfy to avoid the CCE error. Experiments show that our scheme can search all entries, and the probability of searching error is reduced to less than 2-37.4 .

SUMMARY E2, a block cipher, is an Advanced Encryption Standard candidate designed and submitted by Nippon Telegraph and Telephone Corporation. It employs a Feistel structure as global structure and two‐layer substitution–permutation network structure in round function. The conservative structure makes E2 immune to kinds of current cryptanalysis. Previously, there is no result of impossible differential attacks on E2 because it was once supposed to have no more than five‐round impossible differential characteristic. In this paper, we present a series of six‐round impossible differential characteristics of E2 with/without initial transformation (IT)/ final transformation (FT) functions. Based on these impossible differentials, the immunity of E2 against impossible differential cryptanalysis is evaluated. We perform a seven‐round attack on tweaked E2 (E2 without IT and FT ) with 128, 192, and 256 bits key and an eight‐round attack on tweaked E2 with 256 bits key. The seven‐round attack requires about 2120 chosen plaintexts and 2115.5 seven‐round encryptions; the eight‐round attack needs 2121 chosen plaintexts and less than 2214 eight‐round encryptions. We also discuss the seven‐round attack on E2 with IT or FT, and the result shows that the attack has the same complexities with the seven‐round attack on tweaked E2. Copyright © 2013 John Wiley & Sons, Ltd.

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.

At Pairing'07, Matsuo proposed two proxy re-encryption schemes: proxy re-encryption fromCBE to IBE and IBE to IBE. Now both schemes have been standardized by P1363.3workgroup. In this paper, we show that their identity based proxy re-encryption scheme is insecure. We give two attacks to this scheme. The first attack shows that the proxy can re-encrypt any IBE user's ciphertext to be the delegatee's ciphertext. The second attack implies that, if the proxy colludes with any delegatee, the proxy and this delegatee can derive any other IBE user's secret key.

The concept of proxy re-cryptography comes from the work of Blaze, Bleumer, and Strauss in 1998. The goal of proxy re-encryption is to securely enable the re-encryption of ciphertexts from one key to another, without relying on trusted parties. In 2007, Matsuo proposed the concept of four types of proxy re-encryption schemes: CBE to CBE, IBE to CBE, CBE to IBE and IBE to IBE. Now CBE to IBE and IBE to IBE proxy re-encryption schemes are being standardized by IEEEP1363.3 working group. One feature of their schemes is that they are all based on BB1 identity based encryption. We reconsider the problem of constructing proxy re-encryption based on SK identity based encryption. Surprisingly, if we consider the help of PKG, then it is easy to construct proxy re-encryption based on SK identity based encryption. Interestingly , our proxy re-encryption scheme even can achieve CCA2 secure, which makes it is unique.

First we revisit three (BGLS, MBGLS and GZZ) verifiably encrypted signature schemes. We find that they are all not strong unforgeable. We remark that the notion of existential unforgeable is not sufficient for fair exchange protocols in most circumstances. So we propose three new (NBGLS, MBGLS and NGZZ) verifiably encrypted signature schemes which are strong unforgeable. Also we reconsider other two (ZSS and CA) verifiably encrypted signature schemes we find that they both cannot resist replacing public key attack. So we strongly suggest that strong unforgeable for verifiably encrypted signature be a better notion than existential unforgeable and checking adjudicator knowing its private key is a necessary step for secure verifiably encrypted signature scheme.

If the user can compress the multimedia repeatedly, it will decrease the numbers of different resolution copies largely, and then reduce the transmission volume. Combining tamper-detection with DCT-based multi-compression will bring great benefit to the owner in copyright protection system. By embedding the information into the maximal quantized DCT coefficient, the user may make compression with the production in some distance, and finally the integrity of the content will be authenticated. An authenticating algorithm with multi-compression compatible is presented in this paper. The experiment shows that this semi-fragile watermarking algorithm can meet the need of multi-compress, permit the authentication pass, detect the malicious tamper, and obtain better imperceptibly as well as robustness.

Blind signature is very important technology in secure e-commerce. Certificateless public key cryptography avoids the using of certificate in certificate-based public key signature scheme and removes key escrow in ID-based signature scheme. In this paper we introduce the notion of blind signature into certificateless public key cryptography and propose a concrete certificateless blind signature scheme. In terms of computational cost, totally, only one pairing operation is required for blind signing and verification. The security models of certificateless blind signature are also formalized. This scheme is provably secure against a super Type I/II adaptively chosen message and chosen identity adversary in random oracle model.

To improve the survivability of distributed storage systems, using the theory of similarity transformation of Jordan standard shape in theory of matrix, combining the method of Lagrange interpolation method, we design a safe and high-efficient data distributing algorithm with(r,n)threshold scheme. This algorithm has higher efficiency, stronger security and survivability than reference. It has important applications in the intensive data distributed storage system and some storage scenes which have very high expectations for survivability.

We propose a Wavelet based Markov Chain (WBMC) model for nature images, which can present statistic divergence between cover image and steg image prominently. Based on Markov chain empirical matrix, we discussed the difference between low frequency domain and high frequency domain generalized by steg process, and then defined two models: WBMC_L model and WBMC_H model respective to construct our WBMC model. This model relied most on the statistic relativity of coefficients. At last, many experiment results are given to support our theory.

An audio digital signature algorithm based on principal component analysis (PCA) was presented. Wavelet packet decomposition was implemented to audio files, all the terminal coefficients of the wavelet packet decomposing tree were used as the data matrix. The matrix was chaotically encrypted, and then it was principal component analysis that to get the eigenvector. Quantized eigenvector matrix was used as the signature, and the signature was embedded into the primal audio data by using watermarking system, and at the same time ICA technology was introduced to locate the audio tamper. The experiment results confirm that the signature is sensitive to the change of the audio data and can locate the tamper.

Multi-receiver signcryption is a new cryptographic primitive that simultaneously fulfills both the functions of signature and multi-receiver encryption. Generalized Multi-Receiver signcryption can provide authenticity or confidentiality separately under specific inputs. Based on ECDSA, a generalized Multi-Receiver signcryption scheme is designed. It will be equivalent to ECDSA or multi-receiver encryption when one of party is absent. Compared with others, this scheme is based on the efficient and provably secure scheme ECDSA. It can work with three modes: signcryption, signature and encryption. A trusted party can verify the signcryption text publicly in the method of ECDSA.