Non-Committing Encryption is Too Easy in the Random Oracle Model

The non-committing encryption problem arises in the setting of adaptively secure cryptographic protocols, as the task of implementing secure channels. We prove that in the random oracle model, where the parties have oracle access to a uniformly random function, non-committing encryption can be implemented efficiently using any trapdoor permutation.<br /> <br />We also prove that no matter how the oracle is instantiated in practice the resulting scheme will never be non-committing, and we give a short discussion of the random oracle model in light of this.

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On Pseudo-Random Oracles

Tatra Mountains Mathematical Publications ◽

10.2478/v10127-012-0045-5 ◽

2012 ◽

Vol 53 (1) ◽

pp. 155-187

Author(s):

Michal Rjaško

Keyword(s):

Hash Function ◽

Random Function ◽

Hash Functions ◽

Random Oracle Model ◽

Random Oracle ◽

Public Image ◽

Signature Schemes ◽

Random Oracles ◽

Random Behavior ◽

Domain Extension

ABSTRACT Many cryptographic systems which involve hash functions have proof of their security in a so called random oracle model. Behavior of hash functions used in such cryptographic systems should be as close as possible to the behavior of a random function. There are several properties of hash functions dealing with a random behavior. A hash function is pseudo-random oracle if it is indifferentiable from a random oracle. However, it is well known that hash functions based on the popular Merkle-Damg˚ard domain extension transform do not satisfy the pseudo-random oracle property. On the other hand no attack is known for many concrete applications utilizing Merkle-Damg˚ard hash functions. Hence, a weakened notion called public-use pseudo random oracle was introduced. The property can be met by the Merkle-Damg˚ard construction and is sufficient for several important applications. A hash function is public use pseudo-random oracle if it is indifferentiable from a random oracle with public messages (i.e., all messages hashed so far are available to all parties). This is the case of most hash based signature schemes. In this paper we analyze relationship between the property pseudo-random oracle and its variant public image pseudo-random oracle. Roughly, a hash function is public image pseudo-random oracle if it is indifferentiable from a random oracle with public images (i.e., all images of messages hashed so far are available to all parties, messages are kept secret). We prove that the properties are equivalent.

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Mechanizing the Proof of Adaptive, Information-Theoretic Security of Cryptographic Protocols in the Random Oracle Model

2017 IEEE 30th Computer Security Foundations Symposium (CSF) ◽

10.1109/csf.2017.36 ◽

2017 ◽

Cited By ~ 1

Author(s):

Alley Stoughton ◽

Mayank Varia

Keyword(s):

Random Oracle Model ◽

Random Oracle ◽

Cryptographic Protocols ◽

Information Theoretic ◽

Information Theoretic Security

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An Identity-Based Blind Signature Scheme Using Lattice with Provable Security

Mathematical Problems in Engineering ◽

10.1155/2020/7528571 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Quanrun Li ◽

Chingfang Hsu ◽

Debiao He ◽

Kim-Kwang Raymond Choo ◽

Peng Gong

Keyword(s):

Quantum Computer ◽

Rapid Development ◽

Random Oracle Model ◽

Random Oracle ◽

Mean Value ◽

Blind Signature ◽

Signature Scheme ◽

Practical Applications ◽

Universal Quantum ◽

Identity Based

With the rapid development of quantum computing and quantum information technology, the universal quantum computer will emerge in the near decades with a very high probability and it could break most of the current public key cryptosystems totally. Due to the ability of withstanding the universal quantum computer’s attack, the lattice-based cryptosystems have received lots of attention from both industry and academia. In this paper, we propose an identity-based blind signature scheme using lattice. We also prove that the proposed scheme is provably secure in the random oracle model. The performance analysis shows that the proposed scheme has less mean value of sampling times and smaller signature size than previous schemes. Thus, the proposed scheme is more suitable for practical applications.

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ID-based key-insulated signcryption with equality test in cloud computing

SN Applied Sciences ◽

10.1007/s42452-021-04469-9 ◽

2021 ◽

Vol 3 (4) ◽

Author(s):

Seth Alornyo ◽

Kingsford Kissi Mireku ◽

Mustapha Adamu Mohammed ◽

Daniel Adu-Gyamfi ◽

Michael Asante

Keyword(s):

Cloud Computing ◽

Random Oracle Model ◽

Random Oracle ◽

Harsh Environments ◽

Secret Key ◽

Secret Keys ◽

Security Property ◽

Equality Test ◽

Chosen Ciphertext Attack ◽

Chosen Message Attack

AbstractKey-insulated encryption reduces the problem of secret key exposure in hostile setting while signcryption cryptosystem attains the benefits of digitally signing a ciphertext and public key cryptosystem. In this study, we merge the primitives of parallel key-insulation cryptosystem and signcryption with equality test to construct ID-based parallel key-insulated signcryption with a test for equality (ID-PKSET) in cloud computing. The construction prevent data forgery, data re-play attacks and reduces the leakage of secret keys in harsh environments. Our scheme attains the security property of existential unforgeable chosen message attack (EUF-CMA) and indistinquishable identity chosen ciphertext attack (IND-ID-CCA2) using random oracle model.

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