Research On Provably Secure Identity-based Public Key Cryptography Scheme Under Key Compromise Attack

With the rise of internet of things,cloud computing,big data and other new network forms and service environment,more and more cryptosystems are applied to the occasions with poor security,such as mobile devices.Attackers in these occasions can obtain the internal state of system secret information through various side channel attacks(such as time attack,power consumption,cold start attack and spectrum analysis,etc.),which are called the key leakage attacks.Under the key leakage attacks,the events with key leakage in cryptosystems occur frequently.Therefore,it is an important research direction in the field of cryptography to design the provably secure public-key cryptosystems to resist the key leakage attacks.Identity-based cryptosystem is a modification public-key cryptosystems,it gets wide attention because it can greatly simplify the management of public-key certificate.However,the traditional identity-based cryptosystems are all based on the premise of perfect secret key,but this assumption is not true in practice,many provable secure identity-based encryption schemes in traditional secure model are unable to guarantee their claimed security.In order to better meet the practical application,leakage-resilient identity-based cryptosystem is emerging.Leakage-resilient identity-based cryptosystem is designed to take the cases of key leakage into account,it has become one of the hotspots in the field of cryptography.This thesis focuses on studing leakage-resilient identity-based cryptosystems under the key leakage attacks.Through the analysis and research on the existing leakage-resilient identity-based cryptographic schemes,it is found that there are still some deficiencies:(1)Identity-based hash proof system is an important tool to construct leakage-resilient cryptosystems,however,most of identity-based hash proof systems are not anonymous.At present,the existing anonymous identity-based hash proof systems are either constructed under the random oracle model or based on the non-static assumption,which extremely limits the application in leakage-resilient identity-based cryptosystems.(2)The existing anonymous identity-based encryption schemes are all based on the premise of perfect secret key,but this assumption is not true in practice,many anonymous identity-based encryption schemes are unable to guarantee their claimed security under the key leakage attacks.(3)Wicked identity-based encryption(wicked IBE)allows more general key derivation patterns,it is an extension of hierarchical identity based encryption(HIBE).But the existing leakage-resilient wicked identity-based encryption schemes only can resist the bounded key leakage attack,failure to capture more general form of key leakage attacks,like as the continual leak age attack,auxiliary-inputs leakage attack,etc.For the above deficiencies in the existing identity-based cryptosystems,the security of identity-based cryptosystems against the key leakage attacks is studied mainly in this thesis,including the description of the security model,the definition of security,the construction of the cryptosystems,the security proof and performance analysis of the cryptosystems.Specifically,the work of this thesis mainly includes the following aspects:(1)Based on the static assumptions in composite order bilinear groups,we construct an anoymous identity-based hash proof system.Hash proof system is a basic tool for the construction of leakage-resilient cryptosystems.The anonymous identity-based hash proof system proposed in this thesis lays a foundation for the construction of leakage-resilient anonymous identity-based encryption scheme,its anonymity is achieved by blinding the public parameters and ciphertexts using the random elements of an extra subgroup.The security properties of the hash proof system are proved by dual system encryption technology under the standard model.Compared with the existing anonymous identity-based hash proof systems,the scheme constructed in this thesis has higher security.(2)In order to resist key leakage attacks without disclosing the identity of the receiver,this thesis researches on the anonymous IBE thoroughly,a fully secure leakage-resilient anonymous IBE scheme and a chosen-ciphertext secure leakage-resilient anonymous IBE scheme are constructed under the standard model respectively.Both schemes can ensure the high efficiency while the securities of them are improved,at the same time,they can provide certain privacy protection for user.(3)To resist the key leakage attacks,a wicked identity-based encryption scheme resilient to continual auxiliary-inputs(CAI)leakage is proposed in this thesis.The scheme can resist more general form of key leakage and tolerate the continual leakage from the master secret key and the user secret keys,meanwhile,it can achieve full security to resist the adaptive chosen-identity attack and the adaptive chosen-plaintext attack.Compared with the existing schemes,our scheme has better performance in leakage resilience and security.