TP-PRE: threshold progressive proxy re-encryption, its definitions, construction and applications

Autor: B. R. Purushothama, Gaurav Pareek
Rok vydání: 2020
Předmět:
Zdroj: Journal of Ambient Intelligence and Humanized Computing. 12:1943-1965
ISSN: 1868-5145
1868-5137
DOI: 10.1007/s12652-020-02285-4
Popis: Proxy re-encryption (PRE) is a public-key cryptography primitive that delegates the decryption capabilities of a user (called delegator) to another user (called delegatee) using a re-encryption key. A semi-trusted proxy uses the re-encryption key to transform a ciphertext under the delegator’s public key such that it becomes a ciphertext under the delegatee’s public key. If instead of “all”, a delegator wishes to delegate a subset of his decryption capabilities, there is a need for elevating the level of trust in the re-encrypting proxy. As a result, PRE in multi-proxy scenario has received significant research attention in recent times. In this paper, we introduce a new PRE primitive in a multi-proxy setting called Threshold Progressive Proxy Re-encryption (TP-PRE), that involves progressive transformation of ciphertext and results in production of a valid re-encrypted ciphertext if and only if at least t out of the total N distinct proxies perform re-encryption. The way these proxies are selected for re-encryption is significantly different from the existing threshold proxy cryptosystems. The TP-PRE scheme we present does not require prior knowledge about the available proxies. Proxies can take turn in any order to progressively transform the ciphertext and output of $$t{\mathrm{th}}$$ transformation, or any transformation(s) afterward, is the final re-encrypted ciphertext that can be successfully decrypted by the intended delegatee to obtain the correct underlying plaintext. Unlike conventional threshold cryptosystems, TP-PRE does not have a share combination phase hence it does not require any central dealer. We formally define system model and security notions for TP-PRE. We present a concrete construction for TP-PRE that satisfies indistinguishability under chosen-plaintext attacks (IND-CPA) and formally prove its security. We analyze the performance of our construction by providing theoretical bounds of the solution along with the results of practical implementation.
Databáze: OpenAIRE
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