Cryptanalysis and improvement of a pairing-free certificateless signature scheme

Cryptanalysis and improvement of a pairing-free certificateless signature scheme
پانزدهمین کنفرانس بین ‌المللی انجمن رمز ایران
تهران
تاریخ کنفرانس: 
سه شنبه - ۰۶ شهريور ۱۳۹۷ تا چهارشنبه - ۰۷ شهريور ۱۳۹۷
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چکیده

Certificateless signature (CLS) schemes aim to eliminate the need of certificates in traditional public-key signature schemes and also to resolve the inherent key-escrow problem of identity-based signature schemes.‎ There are a vast number of secure CLS schemes in the literature;‎ however, the usage of map-to-point hash functions and bilinear pairings in their constructions makes them less efficient to be applicable in many real-world applications.‎ Recently, Karati et al.‎ proposed an elliptic curve based CLS scheme in which there exists neither any bilinear pairing nor any map-to-points hash function.‎ The authors claimed that the proposed CLS scheme is existentially unforgeable against both types of adversaries considered in certificateless cryptography.‎ However, in this paper, we show that this claim is wrong and a type-1 adversary of certificateless cryptography can forge the signature of any signer on any message of his choice in this scheme.‎ We further slightly modify Karati et al.‎’s scheme in order to make it secure in the standard security model of a CLS scheme.‎ Meanwhile, the proposed improved scheme preserves all the efficiency properties of Karati et al.‎’s scheme.‎

استناد: 

Pakniat, Nasrollah, and Behnam Abasi Vanda.‎ 2018.‎ Cryptanalysis and improvement of a pairing-free certificateless signature scheme. Paoer presented at 15th International ISC (Iranian Society of Cryptology) Conference on Information Security and Cryptology (ISCISC), Tehran.‎

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