Biblio

Ensuring sustainable sourcing of crude materials and production of goods is a pressing problem in consideration of the growing world population and rapid climate change. Supply-chain traceability systems based on distributed ledgers can help to enforce sustainability policies like production limits. We propose two mutually independent distributed-ledger-based protocols that enable public verifiability of policy compliance. They are designed for different supply-chain scenarios and use different privacy-enhancing technologies in order to protect confidential supply-chain data: secret sharing and homomorphic encryption. The protocols can be added to existing supply-chain traceability solutions with minor effort. They ensure confidentiality of transaction details and offer public verifiability of producers' compliance, enabling institutions and even end consumers to evaluate sustainability of supply chains. Through extensive theoretical and empirical evaluation, we show that both protocols perform verification for lifelike supply-chain scenarios in perfectly practical time.

Cloud computing enables users and organizations to conveniently store and share data in large volumes and to enjoy on-demand services. Security and the protection of big data sharing from various attacks is the most challenging issue. Proxy re-encryption (PRE) is an effective method to improve the security of data sharing in the cloud environment. However, in PRE schemes, offloading big data for re-encryption will impose a heavy computational burden on the cloud proxy server, resulting in an increased computation delay and response time for the users. In this paper, we propose a novel parallel PRE workload distribution scheme to dynamically route the big data re-encryption process into the fog of the network. Moreover, this paper proposes a dynamic load balancing technique to avoid an excessive workload for the fog nodes. It also uses lightweight asymmetric cryptography to provide end-to-end security for the big data sharing between users. Within the proposed scheme, the offloading overhead on the centralized cloud server is effectively mitigated. Meanwhile, the processing delay incurred by the big data re-encryption process is efficiently improved.

In this paper, the role re-encryption is used to avoid the privacy data lekage and also to avoid the deduplication in a secure role re-encryption system(SRRS). And also it checks for the proof of ownership for to identify whether the user is authorized user or not. This is for the efficiency. Role re-encrytion method is to share the access key for the corresponding authorized user for accessing the particular file without the leakage of privacy data. In our project we are using both the avoidance of text and digital images. For example we have the personal images in our mobile, handheld devices, and in the desktop etc., So, as these images have to keep secure and so we are using the encryption for to increase the high security. The text file also important for the users now-a-days. It has to keep secure in a cloud server. Digital images have to be protected over the communication, however generally personal identification details like copies of pan card, Passport, ATM, etc., to store on one's own pc. So, we are protecting the text file and image data for avoiding the duplication in our proposed system.

Nowadays, massive amounts of data are stored in the cloud, how to access control the cloud data has become a prerequisite for protecting the security of cloud data. In order to address the problems of centralized control and privacy protection in current access control, we propose an access control scheme based on the blockchain and re-encryption technology, namely PERBAC-BC scheme. The access control policy is managed by the decentralized and immutability characteristics of blockchain, while the re-encryption is protected by the trusted computing characteristic of blockchain and the privacy is protected by the identity re-encryption technology. The overall structure diagram and detailed execution flow of the scheme are given in this paper. Experimental results show that, compared with the traditional hybrid encryption scheme, the time and space consumption is less when the system is expanded. Then, the time and space performance of each part of the scheme is simulated, and the security of blockchain is proved. The results also show that the time and space performance of the scheme are better and the security is stronger, which has certain stability and expandability.

Unmanned Aerial Vehicles (UAVs) also known as drones are being used in many applications where they can record or stream videos. One interesting application is the Intelligent Transportation Systems (ITS) and public safety applications where drones record videos and send them to a control center for further analysis. These videos are shared by various clients such as law enforcement or emergency personnel. In such cases, the recording might include faces of civilians or other sensitive information that might pose privacy concerns. While the video can be encrypted and stored in the cloud that way, it can still be accessed once the keys are exposed to third parties which is completely insecure. To prevent such insecurity, in this paper, we propose proxy re-encryption based sharing scheme to enable third parties to access only limited videos without having the original encryption key. The costly pairing operations in proxy re-encryption are not used to allow rapid access and delivery of the surveillance videos to third parties. The key management is handled by a trusted control center, which acts as the proxy to re-encrypt the data. We implemented and tested the approach in a realistic simulation environment using different resolutions under ns-3. The implementation results and comparisons indicate that there is an acceptable overhead while it can still preserve the privacy of drivers and passengers.

Security of cloud storage and sharing is concerned for years since a semi-trusted party, Cloud Server Provider (CSP), has access to user data on cloud server that may leak users' private data without constraint. Intuitively, an efficient solution of protecting cloud data is to encrypt it before uploading to the cloud server. However, a new requirement, data sharing, makes it difficult to manage secret keys among data owners and target users. Therefore conditional proxy broadcast re-encryption technology (CPBRE) is proposed in recent years to provide data encryption and sharing approaches for cloud environment. It enables a data owner to upload encrypted data to the cloud server and a third party proxy can re-encrypted cloud data under certain condition to a new ciphertext so that target users can decrypt re-encrypted data using their own private key. But few CPBRE schemes are applicable for a dynamic cloud environment. In this paper, we propose a new dynamic conditional proxy broadcast reencryption scheme that can be dynamic in system user setting and target user group. The initialization phase does not require a fixed system user setup so that users can join or leave the system in any time. And data owner can dynamically change the group of user he wants to share data with. We also provide security analysis which proves our scheme to be secure against CSP, and performance analysis shows that our scheme exceeds other schemes in terms of functionality and resource cost.

It is quite common nowadays for clients to outsource their personal data to a cloud service provider. However, it causes some new challenges in the area of data confidentiality and access control. Attribute-based encryption is a promising solution for providing confidentiality and fine-grained access control in a cloud-based cryptographic system. Moreover, in some cases, to preserve the privacy of clients and data, applying hidden access structures is required. Also, a data owner should be able to update his defined access structure at any time when he is online or not. As in several real-world application scenarios like e-health systems, the anonymity of recipients, and the possibility of updating access structures are two necessary requirements. In this paper, for the first time, we propose an attribute-based access control scheme with hidden access structures enabling the cloud to update access structures on expiry dates defined by a data owner.

In last few years, Proxy Re-Encryption has been used for forwarding the encrypted message to the user, these users are the one who has not been a part of encryption. In the past several scheme were developed in order to provide the efficient and secure proxy re-encryption. However, these methodology mainly focused on features like maximum key privacy, minimal trust proxy and others. In such cases the efficiency and security was mainly ignored. Hence, in order to provide the efficient and secure proxy re-encryption, we proposed an algorithm named as MLBC (Modified Lattice Based Cryptography) is proposed. Our method is based on the PKE (Public Key Encryption) and it provides more efficiency when compared to the other cryptography technique. Later in order to evaluate the algorithm simulation is done based on several parameter such as encryption time, proxy key generation time, Re-encryption time and Total computation time. Later, it is compared with the existing algorithm and the plotted graph clearly shows that our algorithm outperforms the existing algorithm.

Designing secure, scalable, and resilient IoT networks is a challenging task because of resource-constrained devices and no guarantees of reliable network connectivity. Fog computing improves the resiliency of IoT, but its security model assumes that fog nodes are fully trusted. We relax this latter constraint by proposing a solution that guarantees confidentiality of messages exchanged through semi-honest fog nodes thanks to a lightweight proxy re-encryption scheme. We demonstrate the feasibility of the solution by applying it to IoT networks of low-power devices through experiments on microcontrollers and ARM-based architectures.

Cloud computing undoubtedly is the most unparalleled technique in rapidly developing industries. Protecting sensitive files stored in the clouds from being accessed by malicious attackers is essential to the success of the clouds. In proxy re-encryption schemes, users delegate their encrypted files to other users by using re-encryption keys, which elegantly transfers the users' burden to the cloud servers. Moreover, one can adopt conditional proxy re-encryption schemes to employ their access control policy on the files to be shared. However, we recognize that the size of re-encryption keys will grow linearly with the number of the condition values, which may be impractical in low computational devices. In this paper, we combine a key-aggregate approach and a proxy re-encryption scheme into a key-aggregate proxy re-encryption scheme. It is worth mentioning that the proposed scheme is the first key-aggregate proxy re-encryption scheme. As a side note, the size of re-encryption keys is constant.

In recent years, many users have uploaded data to the cloud for easy storage and sharing with other users. At the same time, security and privacy concerns for the data are growing. Attribute-based encryption (ABE) enables both data security and access control by defining users with attributes so that only those users who have matching attributes can decrypt them. For real-world applications of ABE, revocation of users or their attributes is necessary so that revoked users can no longer decrypt the data. In actual implementations, ABE is used in hybrid with a symmetric encryption scheme such as the advanced encryption standard (AES) where data is encrypted with AES and the AES key is encrypted with ABE. The hybrid encryption scheme requires re-encryption of the data upon revocation to ensure that the revoked users can no longer decrypt that data. To re-encrypt the data, the data owner (DO) must download the data from the cloud, then decrypt, encrypt, and upload the data back to the cloud, resulting in both huge communication costs and computational burden on the DO depending on the size of the data to be re-encrypted. In this paper, we propose an attribute-based proxy re-encryption method in which data can be re-encrypted in the cloud without downloading any data by adopting both ABE and Syalim's encryption scheme. Our proposed scheme reduces the communication cost between the DO and cloud storage. Experimental results show that the proposed method reduces the communication cost by as much as one quarter compared to that of the trivial solution.

Inner-product encryption (IPE) is a well-known functional encryption primitive that allows decryption when the inner-product of the attribute vectors, upon which the encrypted data and the decryption key depend, is equal to zero. Using IPE, it is possible to define fine-grained access policies over encrypted data whose enforcement can be outsourced to the cloud where the data are stored. However, current IPE schemes do not support efficient access policy changes. In this paper, we propose an efficient inner-product proxy re-encryption (E-IPPRE) scheme that provides the proxy server with a transformation key, with which a ciphertext associated with an attribute vector can be transformed to a new ciphertext associated with a different attribute vector, providing a policy update mechanism with a performance suitable for many practical applications. We experimentally assess the efficiency of our protocol and show that it is selective attribute-secure against chosen-plaintext attacks in the standard model under the Asymmetric Decisional Bilinear Diffie-Hellman assumption.

Outsourcing the decryption of attribute-based encryption (ABE) ciphertext is a promising way to tackle the question of how users can perform decryption efficiently. However, existing solutions require the type of the target ciphertext to be determined at the setup of the outsourcing scheme. As such, making the target cryptosystems (or the clients) to be versatile becomes an issue that warrants investigations. In this paper, the problem we wish to tackle is to transform an ABE ciphertext to any client who is using the same, or possibly different, public-key encryption (PKE) system with the sender. The problem is of practical interest since it is hard to require all clients to use the same PKE, especially in the case of remote and cross-system data sharing. In addition, we also consider whether robust client-side decryption scheme can be adopted. This feature is not supported in the existing ABE with outsourcing. We introduce cross-system proxy re-encryptions (CS-PRE), a new re-encryption paradigm in which a semi-trusted proxy converts a ciphertext of a source cryptosystem (\$\textparagraphi\_0\$) into a ciphertext for a target cryptosystem (\$\textparagraphi\$). We formalize CS-PRE and present a construction that performs well in the following aspects. (1)Versatility: \$\textparagraphi\_0\$ can be any attribute-based encryption (ABE) within Attrapadung's pair encoding framework. \$\textparagraphi\$ can be any public-key encryption. Furthermore, the keys and public parameters can be generated independently. (2) Compatibility: CS-PRE does not modify the public parameters and keys of \$\textparagraphi\_0\$ and \$\textparagraphi\$. Besides, input for the conversion is an ordinary ciphertext of \$\textparagraphi\_0\$. (3) Efficiency: The computational cost for re-encryption and decryption of the re-encrypted ciphertext are roughly the same as a decryption in \$\textparagraphi\_0\$ and \$\textparagraphi\$ respectively. We prove that our construction is fully secure assuming \$\textparagraphi\_0\$ is secure in Attrapadung's framework and \$\textparagraphi\$ is IND-CPA secure. Furthermore, it remains secure when there are multiple target cryptosystems. As with other proxy re-encryption, CS-PRE enables flexible sharing of cloud data, as the owner can instruct the cloud server to re-encrypt his ciphertext to those for the intended recipient. In addition, it allows lightweight devices to enjoy access to remote data encrypted under powerful but possibly costly encryption, such as functional encryption, by utilizing the server's power in converting the ciphertext to a simpler encryption, such as RSA. Finally, instances of CS-PRE can be viewed as new proxy re-encryption schemes, such as a PRE supporting ABE for regular language to Hierarchical IBE or Doubly Spatial Encryption to lattice-based encryptions (e.g. NTRUCCA).

Enhancing trust among service providers and end-users with respect to data protection is an urgent matter in the growing information society. In response, CREDENTIAL proposes an innovative cloud-based service for storing, managing, and sharing of digital identity information and other highly critical personal data with a demonstrably higher level of security than other current solutions. CREDENTIAL enables end-to-end confidentiality and authenticity as well as improved privacy in cloud-based identity management and data sharing scenarios. In this paper, besides clarifying the vision and use cases, we focus on the adoption of CREDENTIAL. Firstly, for adoption by providers, we elaborate on the functionality of CREDENTIAL, the services implementing these functions, and the physical architecture needed to deploy such services. Secondly, we investigate factors from related research that could be used to facilitate CREDENTIAL's adoption and list key benefits as convincing arguments.

Proxy Re-encryption (PRE) is a useful cryptographic structure who enables a semi-trusted proxy to convert a ciphertext for Alice into a ciphertext for Bob without seeing the corresponding plaintext. Although there are many PRE schemes in recent years, few of them are set up based on lattice. Not only this, these lattice-based PRE schemes are all more complicated than the traditional PRE schemes. In this paper, through the study of the common lattice problems such as the Small integer solution (SIS) and the Learning with Errors (LWE), we analyze the feasibility of efficient lattice-based PRE scheme combined with the previous results. Finally, we propose an efficient lattice-based PRE scheme L-PRE without losing the hardness of lattice problems.

In the big data era, many users upload data to cloud while security concerns are growing. By using attribute-based encryption (ABE), users can securely store data in cloud while exerting access control over it. Revocation is necessary for real-world applications of ABE so that revoked users can no longer decrypt data. In actual implementations, however, revocation requires re-encryption of data in client side through download, decrypt, encrypt, and upload, which results in huge communication cost between the client and the cloud depending on the data size. In this paper, we propose a new method where the data can be re-encrypted in cloud without downloading any data. The experimental result showed that our method reduces the communication cost by one quarter in comparison with the trivial solution where re-encryption is performed in client side.

Proxy Re-Encryption (PRE) is a favorable primitive to realize a cryptographic cloud with secure and flexible data sharing mechanism. A number of PRE schemes with versatile capabilities have been proposed for different applications. The secure data sharing can be internally achieved in each PRE scheme. But no previous work can guarantee the secure data sharing among different PRE schemes in a general manner. Moreover, it is challenging to solve this problem due to huge differences among the existing PRE schemes in their algebraic systems and public-key types. To solve this problem more generally, this paper uniforms the definitions of the existing PRE and Public Key Encryption (PKE) schemes, and further uniforms their security definitions. Then taking any uniformly defined PRE scheme and any uniformly defined PKE scheme as two building blocks, this paper constructs a Generally Hybrid Proxy Re-Encryption (GHPRE) scheme with the idea of temporary public and private keys to achieve secure data sharing between these two underlying schemes. Since PKE is a more general definition than PRE, the proposed GHPRE scheme also is workable between any two PRE schemes. Moreover, the proposed GHPRE scheme can be transparently deployed even if the underlying PRE schemes are implementing.

The emerging Information-Centric Networking (ICN) paradigm is expected to facilitate content sharing among users. ICN will make it easy for users to appoint storage nodes, in various network locations, perhaps owned or controlled by them, where shared content can be stored and disseminated from. These storage nodes should be (somewhat) trusted since not only they have (some level of) access to user shared content, but they should also properly enforce access control. Traditional forms of encryption introduce significant overhead when it comes to sharing content with large and dynamic groups of users. To this end, proxy re-encryption provides a convenient solution. In this paper, we use Identity-Based Proxy Re-Encryption (IB-PRE) to provide confidentiality and access control for content items shared over ICN, realizing secure content distribution among dynamic sets of users. In contrast to similar IB-PRE based solutions, our design allows each user to generate the system parameters and the secret keys required by the underlay encryption scheme using their own \textbackslashemph\Private Key Generator\, therefore, our approach does not suffer from the key escrow problem. Moreover, our design further relaxes the trust requirements on the storage nodes by preventing them from sharing usable content with unauthorized users. Finally, our scheme does not require out-of-band secret key distribution.