Fast and Secure Updatable Encryption

Boyd, Colin; Davies, Gareth T.; Gjøsteen, Kristian; Jiang, Yao

doi:10.1007/978-3-030-56784-2_16

Cited by 35 publications

(45 citation statements)

References 26 publications

(46 reference statements)

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“…Giving the relevant security notion to consider according to a given leakage context, as done above, we show that the IND-UE security notion of Boyd et al [9] is not always stronger than the one of [32], namely IND-(ENC + UPD).…”

Section: Contributionsmentioning

confidence: 81%

“…Definitions We follow the syntax given in [9]. A UE scheme is given by a tuple of algorithms (KG, TG, Enc, Dec, Upd) operating in epochs over message space M, ciphertext space C, key space K and token space T .…”

Section: Updatable Encryptionmentioning

confidence: 99%

“…In previous works, the security of UE is described using security games. We will analyze the differences between the IND-ENC + IND-UPD security notion of [32] and the IND-UE one of [9].…”

Section: Security Notionsmentioning

confidence: 99%

“…We will study the confidentiality of UE schemes in the CPA setting of [9] where the adversary has access to both an encryption and an update oracle. We recall the different game oracles used in the CPA setting of [9] in fig. 20 of the appendix.…”

Section: Security Notionsmentioning

confidence: 99%

“…UE allows a client, who outsourced his encrypted data, to make an untrusty server update it. The huge real-life applications of such a functionality explains the recent renew of interest on the subject [17,32,28,23,9]. The concept and definition of UE first appeared in a paper by Boneh et al in 2013 [8], as an application of key homomorphic PRFs to the context of rotating keys for encrypted data stored in the cloud.We are here interested in the ciphertext-independent variant of UE, i.e., the one in which a token dependent only on the old and new keys is used to update all ciphertexts.…”

mentioning

confidence: 99%

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Interactivity in Constructive Cryptography : Modeling and Applications to Updatable Encryption and Private Information Retrieval

Levy-dit-Vehel¹,

Roméas²

2022

Preprint

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In this work, we extend the Constructive Cryptography (CC) framework introduced by Maurer in 2011 so as to handle interactive protocols. We design and construct a so-called Interactive Server Memory Resource (ISMR), that is an augmented version of the basic instantiation of a client-server protocol in CC, namely the Server Memory Resource. We then apply our ISMR construction to two types of interactive cryptographic protocols for remote storage : Updatable Encryption (UE) and Private Information Retrieval (PIR). Concerning UE, our results are a composable version of those protocols, clarifying the security guarantees achieved by any UE scheme. Namely, we give the relevant security notion to consider according to a given leakage context. Letting USMR denote our ISMR adapted to the UE application, we prove that IND-UE-CPA security is sufficient for a secure construction of a confidential USMR that hides the age of ciphertexts; and IND-(ENC+UPD)-CPA security is sufficient for a secure construction of a confidential USMR in case of unrestricted leakage. As a consequence, contrary to what was claimed before, the IND-UE security notion is not always stronger than the IND-(ENC + UPD) one. Another contribution to CC is a method of proof handling asymmetric challenges, namely game pairs of the form (m, c), i.e. (plaintext, ciphertext), where the oracle either answers an encryption of m or an update of c. Those occur for instance when proving IND-UE-CPA security. Concerning PIR, we also give a composable version of PIR protocols, yielding a unique model that unifies different notions of PIR : IT-PIR, C-PIR, one-or multi-server PIR. Using the flexibility of CC, we are also able to model PIR variants, such as SPIR.CC is a composable framework that was introduced by Maurer [33]. Its topdown approach makes it very intuitive and nice to work with. Badertscher and Maurer [5] first used it in the outsourced storage setting to clarify some security models and build protocols in a modular fashion. Jost et al. [25] introduced the notion of global event history to the theory and give a first treatment of adaptive security. This work was then pursued [24] by introducing interval-wise security guarantees in order to find a way to overcome impossibility results such as the commitment problem.We extend this model by introducing and modeling interactivity in CC. We make this possible by proposing new ways of using of so-called converters and simulators. We illustrate the power and the flexibility of our model on two privacy preserving and interactive schemes : Updatable Encryption (UE) and Private Information Retrieval (PIR). We make their modeling possible by introducing a new proof technique. We think that our treatment of interactivity in CC will permit to more easily build and to better understand the security guarantees of interactive protocols.Updatable Encryption. UE allows a client, who outsourced his encrypted data, to make an untrusty server update it. The huge real-life applications of such a functionality explains the recent ...

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Section: Contributionsmentioning

confidence: 81%

Section: Updatable Encryptionmentioning

confidence: 99%

“…In previous works, the security of UE is described using security games. We will analyze the differences between the IND-ENC + IND-UPD security notion of [32] and the IND-UE one of [9].…”

Section: Security Notionsmentioning

confidence: 99%

Section: Security Notionsmentioning

confidence: 99%

mentioning

confidence: 99%

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Interactivity in Constructive Cryptography : Modeling and Applications to Updatable Encryption and Private Information Retrieval

Levy-dit-Vehel¹,

Roméas²

2022

Preprint

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Toward data privacy preservation with ciphertext update and key rotation for IoT

Shen

Yang

Liu

2021

Concurrency and Computation

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Fine‐grained access control become a research spotlight in the scenario of the smart home with Internet‐of‐Things (IoTs). However, most of the existing works could only realize ciphertext outsourcing with an unchangeable encryption key in the cloud. That is because the trivial solution needs great communication overhead. To overcome this challenge, we propose an updatable encryption based on SM9 (SM9‐UE) scheme for the IoT smart home scenario, where SM9 is an identity and cryptographic standard adopted by GM/T0044. SM9‐UE realizes secure and lightweight ciphertext updating through using the token generated by the data owner, which is information independent with the plaintext. We give the formal security definition and prove it to be adaptive update indistinguishability (IND‐UPD) secure. Theoretical comparison and analysis show that our scheme is efficient in computation and storage overhead. Experimental results also indicate that SM9‐UE can be practically applied to IoT smart home.

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The Direction of Updatable Encryption Does Not Matter Much

Jiang

2020

Advances in Cryptology – ASIACRYPT 2020

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Fast and Secure Updatable Encryption

Abstract: This is the full version. An earlier version of this document was titled 'RISE and SHINE: Fast and Secure Updatable Encryption'. This version subsumes that work and includes new results; we summarize the changes in Section 1.4.

Cited by 35 publications

References 26 publications

Interactivity in Constructive Cryptography : Modeling and Applications to Updatable Encryption and Private Information Retrieval

Interactivity in Constructive Cryptography : Modeling and Applications to Updatable Encryption and Private Information Retrieval

Toward data privacy preservation with ciphertext update and key rotation for IoT

The Direction of Updatable Encryption Does Not Matter Much

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