Storing and Retrieving Secrets on a Blockchain

Goyal, Vipul; Kothapalli, Abhiram; Masserova, Elisaweta; Parno, Bryan; Song, Yifan

doi:10.1007/978-3-030-97121-2_10

Cited by 13 publications

(11 citation statements)

References 42 publications

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“…Liu et al [20] proposed a construction based on multi-linear maps, which can be instantiated from indistinguishability obfuscation (iO) [1], which in turn can be obtained from well-founded assumptions [19], leading to a theoretical instantiation. A different approach was taken by Goyal et al [15] who show how the functionality of extractable witness encryption can be implemented efficiently on a blockchain. This approach is especially appealing in relation to our work due to the obtained efficiency and that our construction already makes use of a blockchain.…”

Section: Instantiating Witness Encryptionmentioning

confidence: 99%

“…This approach is especially appealing in relation to our work due to the obtained efficiency and that our construction already makes use of a blockchain. Note that [15] requires the miners maintaining the blockchain to implement additional functionality i.e. smaller changes would have to be made to existing blockchain protocols to achieve the desired functionality, and to maintain forward security, the communication between miners and the decryptor must be forward secure (e.g.…”

Section: Instantiating Witness Encryptionmentioning

confidence: 99%

“…by using TLS 1.3 [23]). Furthermore, due to the dependency on a blockchain, [15] does not follow the standard definition of witness encryption. However, in this work, we will make use of the standard definitions above.…”

Section: Instantiating Witness Encryptionmentioning

confidence: 99%

“…† † † We note the approach by Goyal et al [15] allows efficient encryption and only requires the decryptor to perform a potentially heavy computation related to the relevant statement and witness.…”

Section: Efficiencymentioning

confidence: 99%

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PoS Blockchain-Based Forward-Secure Public Key Encryption with Immutable Keys and Post-Compromise Security Guarantees

Nuta

Schuldt

Nishide

2023

IEICE Trans. Fundamentals

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We present a forward-secure public-key encryption (PKE) scheme without key update, i.e. both public and private keys are immutable. In contrast, prior forward-secure PKE schemes achieve forward security by constantly updating the secret keys. Our scheme is based on witness encryption by Garg et al. (STOC 2013) and a proof-of-stake blockchain with the distinguishable forking property introduced by Goyal et al. (TCC 2017), and ensures a ciphertext cannot be decrypted more than once, thereby rendering a compromised secret key useless with respect to decryption of past ciphertext the legitimate user has already decrypted.In this work, we formalize the notion of blockchain-based forwardsecure PKE, show the feasibility of constructing a forward-secure PKE scheme without key update, and discuss interesting properties of our scheme such as post-compromise security.

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Section: Instantiating Witness Encryptionmentioning

confidence: 99%

Section: Instantiating Witness Encryptionmentioning

confidence: 99%

Section: Instantiating Witness Encryptionmentioning

confidence: 99%

Section: Efficiencymentioning

confidence: 99%

See 2 more Smart Citations

PoS Blockchain-Based Forward-Secure Public Key Encryption with Immutable Keys and Post-Compromise Security Guarantees

Nuta

Schuldt

Nishide

2023

IEICE Trans. Fundamentals

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“…In particular, the idea of distributing sensitive information to anonymous committees (e.g. privacy revocation trapdoors) or having anonymous committees execute cryptographic protocols has been explored in the context of proactive secret sharing [11,41,26], multiparty computation (MPC) [38] and threshold encryption [35]. These protocols work in the so called You Only Speak Once (YOSO) model, where a fresh randomly chosen anonymous committee executes each round of the protocol, limiting the adversary to probabilistic corruptions (i.e.…”

Section: Related Workmentioning

confidence: 99%

PAPR: Publicly Auditable Privacy Revocation for Anonymous Credentials

Brorsson

David

Gentile

et al. 2023

Lecture Notes in Computer Science

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We study the notion of anonymous credentials with Publicly Auditable Privacy Revocation (PAPR). PAPR credentials simultaneously provide conditional user privacy and auditable privacy revocation. The first property implies that users keep their identity private when authenticating unless and until an appointed authority requests to revoke this privacy, retroactively. The second property enforces that auditors can verify whether or not this authority has revoked privacy from an issued credential (i.e. learned the identity of the user who owns that credential), holding the authority accountable. In other words, the second property enriches conditionally anonymous credential systems with transparency by design, effectively discouraging such systems from being used for mass surveillance. In this work, we introduce the notion of a PAPR anonymous credential scheme, formalize it as an ideal functionality, and present constructions that are provably secure under standard assumptions in the Universal Composability framework. The core tool in our PAPR construction is a mechanism for randomly selecting an anonymous committee which users secret share their identity information towards, while hiding the identities of the committee members from the authority. As a consequence, in order to initiate the revocation process for a given credential, the authority is forced to post a request on a public bulletin board used as a broadcast channel to contact the anonymous committee that holds the keys needed to decrypt the identity connected to the credential. This mechanism makes the user de-anonymization publicly auditable.

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