Research On Leakage-resilient Identity-based Encryption Technology In Cloud Storage

As a burgeoning technology,cloud computing provides great convenience for our daily life.Cloud storage is a popular service in cloud computing,which brings convenience for users to store data.In particular,as cloud storage service is increasingly accepted by the general public,enterprises and individuals are more inclined to upload data to a third-party storage that can provide customized services to users.While it brings convenience to data store,there are some issues such as data privacy security.In order to protect data privacy security,the traditional approach uses the data encryption before outsourced,which can protect data privacy well.However,because of diverse attacks,the attacker can obtain partial key information,which makes the principle of public key disclosure and private key secrecy in the traditional public-key cryptography destroyed.Moreover,the security of the traditional cryptography is destructed.Therefore,for the above-mentioned confidential storage problem,the traditional encryption algorithm may be difficult to ensure the security of the data.Privacy protection is still a huge challenge for existing cloud storage technologies.The proposal of leakage-resilient public key encryption technology can solve the above problems well and guarantee the security of cloud data.Inspired by the existing public-key encryption schemes and different leakage-resilient models,this thesis proposes two encryption schemes that support leakage resilience.The focus of this work,is the leakage resilience and allow private key leakage.The work done in our paper is as follows:(1)We propose a leakage-resilient hierarchical identity-based encryption scheme with recipient anonymity in bounded leakage model.And the length of public parameters,private keys,ciphertext are fixed,and do not vary with the depth of identity hierarchy.This scheme is anonymous,and the attacker can't get any information about the identity of the receiver from the ciphertext,thus protecting users' privacy.In addition,our security proofs based on the dual system encryption technique show that the proposed scheme is capable of resisting key leakage.Efficiency and simulation analysis show that the scheme has higher decryption efficiency.The overall data analysis illustrates the advantages of the proposed approach applied to the cloud storage system.(2)Based on the shortcomings of the bounded leakage model,we propose an identity-based encryption scheme under the continuous leakage model.The scheme achieves the function of leakage-resilience by updating key,and this does not change the length of public key and secret key.The updated private key is indistinguishable from the original private key,so the attacker cannot obtain sufficient valid information to decrypt the ciphertext.Moreover,the secret keys updated several times can still correctly recover the ciphertext message,which can effectively protect the user's data privacy.The comparison of the efficiency and simulation also reflects the practicality of the data security storage system scheme in cloud computing.