Key escrow

About: Key escrow is a research topic. Over the lifetime, 1162 publications have been published within this topic receiving 19616 citations.

Attribute Specified Identity-Based Encryption

Abstract: Fine-grained access control of encrypted data without trusted third party is a challenging task. Using the simple attribute-based encryption has the problem of key escrow, since there exists a trusted authority who is able to generate the secret keys of all users. Delegating this ability to multiple authorities can only minimize the risk, but not eliminating the possibility that all authorities may collude. We develop a new cryptosystem called Attribute Specified Identity-Based Encryption (AS-IBE) to solve this problem. We employ the idea of certificateless encryption and extend it to the attribute-based setting. Each user chooses his own public and secret key pairs to use, in addition to his attribute-based secret key. Therefore, the authority cannot decrypt without the knowledge the user’s own secret key. Yet, the resulting AS-IBE system has some fundamental differences with the original attribute-based encryption. In this paper, we give the security model for the new AS-IBE cryptosystems, and propose two variants for the construction, namely the key policy AS-IBE and ciphertext policy AS-IBE.

A comment on efficient certificateless aggregate signature scheme

Abstract: Certificateless signature scheme provides the solution of key escrow problem inherit in ID based public key cryptography. Aggregate signature allows aggregating of n signature in one single short signature which is very efficient in ad-hoc networks, PDA, mobile computation and more. A certificateless aggregate signature scheme solves not only the certification problem and key escrow problem but also done aggregation of n user's signatures. Recently, Deng et al proposed a certificateless aggregate signature scheme in “Concurrency and Computation: Practice and Experience” [doi: 10.1002/cpe.3551] in 2015 and claims that it is unforgeable under some concrete attacks but during security analysis we found it is insecure by some concrete attacks. In this paper, we show that proposed scheme is forged by universal adversary.

Certificateless threshold decryption scheme secure in the standard model

Abstract: Certificateless cryptography solves the key escrow problem inherent in identity-based cryptography. This paper first presents a practical model for certificateless threshold decryption scheme which avoids both the single point of failure in the distributed networks and the inherent key escrow problem in identity-based cryptosystem. Based on the idea of [9], The paper also introduces the first certificateless threshold decryption scheme that is IND-CCA secure against chosen ciphertext attack in the standard model.

Forward-Secure Certificate-Based Encryption: Definition and Generic Construction

Abstract: Certificate-based encryption (CBE) is a new paradigm which combines traditional public-key encryption (PKE) and identity-based encryption (IBE) while preserving their features. CBE provides an efficient implicit certificate mechanism to eliminate third-party queries for the certificate status and to simplify the certificate revocation problem. Therefore, CBE can be used to construct an efficient PKI requiring fewer infrastructures. In addition, it also solves the key escrow problem and key distribution problem inherent in IBE. In this paper, we introduce a new notion called Forward-Secure Certificate-Based Encryption. It preserves the advantages of CBE such as implicit certificate and no private key escrow. At the same time it also inherits the properties of the forward-secure public key encryption. We first formalize the definition and security model for forward-secure CBE. Then we propose a generic construction of forward-secure CBE and prove it to be secure against chosen plaintext attacks in the standard model. We also describe how our generic scheme can be enhanced to achieve security against adaptive chosen-ciphertext attacks in both the standard model and the random oracle model.

Blockchain based joint blind key escrow

Abstract: A computer-implemented method for escrowing secret data in a server of a client-server network, the client-server network comprising: a first client having at least one public and private client key pairs, at least one trusted client having at least one public and private trusted client key pairs, a server having a public and private server key pairs, a blockchain system comprising a plurality of nodes which are configured to store the public keys of the elements of the client-server network. It is also described a computer-implemented method for obtaining secret data of a server wherein the secret data is escrowed with the above computer-implemented method for escrowing secret data in a server. System, computer-readable mediums and computer programs, which are configured to implement or perform said computer-implemented methods, are also described.