Threshold schemes for cryptographic primitives:

Abstract

The Information Technology Laboratory (ITL) at the National Institute of Standards and Technology (NIST) promotes the U.S. economy and public welfare by providing technical leadership for the Nation's measurement and standards infrastructure. ITL develops tests, test methods, reference data, proof of concept implementations, and technical analyses to advance the development and productive use of information technology. ITL's responsibilities include the development of management, administrative, technical, and physical standards and guidelines for the cost-effective security and privacy of other than national security-related information in federal information systems. AbstractThe Computer Security Division at the National Institute of Standards and Technology is interested in promoting the security of implementations of cryptographic primitives. This security depends not only on the theoretical properties of the primitives but also on the ability to withstand attacks on their implementations. It is thus important to mitigate breakdowns that result from differences between ideal and real implementations of cryptographic algorithms.This document overviews the possibility of implementing cryptographic primitives using threshold schemes, where multiple components contribute to the operation in a way that attains the desired security goals even if f out of n of its components are compromised. There is also an identified potential in providing resistance against side-channel attacks, which exploit inadvertent leakage from real implementations. Security goals of interest include the secrecy of cryptographic keys, as well as enhanced integrity and availability, among others. This document considers challenges and opportunities related to standardization of threshold schemes for cryptographic primitives. It includes examples illustrating security tradeoffs under variations of system model and adversaries. It enumerates several high-level characterizing features of threshold schemes, including the types of threshold, the communication interfaces (with the environment and between components), the executing platform (e.g., single device vs. multiple devices) and the setup and maintenance requirements.The document poses a number of questions, motivating aspects to take into account when considering standardization. A particular challenge is the development of criteria that may help guide a selection of threshold cryptographic schemes. An open question is deciding at what level each standard should be defined (e.g., specific base techniques vs. conceptualized functionalities) and which flexibility of parametrization they should allow. Suitability to testing and validation of implementations are also major concerns to be addressed. Overall, the document intends to support discussion about standardization, including motivating an engagement from stakeholders. This is a step towards enabling threshold cryptography within the US federal government and beyond.

Blockchain networks :

“…One cannot access the tokens and submit transactions without the requisite number of signatures from an m-of-n quorum of private keys. Multi-signature wallets can rely on threshold cryptography 5 [31] to compute the aggregate signature.…”

“…Once the computation is completed, the output is known by all of the nodes. Thus, secure multi-party computation allows multiple parties, often mutually distrustful, to compute some functionality of their inputs as if they were computed by a trusted third party[31] 10. Homomorphic encryption allows encrypted data to be processed without having to be decrypted beforehand.…”

Fully Decentralized Multi-Party Consent Management for Secure Sharing of Patient Health Records

“…Threshold cryptographic schemes are generally encryption and decryption protocols where more than one party can contribute to the operation [28], hence named as MPA. Threshold cryptography can be highly advantageous in decentralized systems that require the approval of m out of n entities for the cryptographic operation to succeed, where m ≤ n, n is the total number of entities involved in the encryption operation and m is the required number of entities for the decryption operation.…”

Blockchain Networks:

“…One cannot access the tokens and submit transactions without the requisite number of signatures from an m-of-n quorum of private keys. Multi-signature wallets can rely on threshold cryptography 5 [27] to compute the aggregate signature.…”

“…Once the computation is completed, the output is known by all of the nodes. Thus, secure multi-party computation allows multiple parties, often mutually distrustful, to compute some functionality of their inputs as if they were computed by a trusted third party [27]. 9 Homomorphic encryption allows encrypted data to be processed without having to be decrypted beforehand.…”