Research On Cryptographic Reverse Firewall For Digital Signature

With the development of the information age,the public begin to realize the convenience of the Internet and bind all aspects of real life to the Internet.However,this convenience is a double-edged sword.When the Snowden revealed the“prism” accident in 2013,people realized that they were under large-scale surveillance.A third party can secretly set up backdoor to leak the user's privacy,while users cannot detect such leak behaviors.In order to solve this problem,researchers have proposed post-Snowden.In2015,Mironov ? Stephens-Davidowitz proposed Cryptographic Reverse Firewall,which is very popular because of its simplicity and convenience.So far,CRFs have been applied in many fields of cryptography such as encryption.As an important field of cryptography,digital signature can provide important properties such as integrity,authentication and non-repudiation.However,it still cannot resist internal attack and face the threat of exfiltration.Ateniese et.al.theoretically proved that CRFs are also suitable for digital signatures,while they do not propose specific model.Undoubtedly,it is extremely meaningful to propose a specific CRFs model for digital signature.The main work of this thesis are as follows:1.We propose a Signature with Cryptographic Reverse Firewall,S-CRF),we deploye CRF for the signer to rerandomize signature and public key.In addition,we design security game to prove that our S-CRF is against existence forgery under adaptive chosen message attack.Meanwhile,our protocol can achieve three basic characteristics of CRFs.Our protocol can resist exfiltration.2.We propose an Identity-Based Signature with Cryptographic Reverse Firewall,IBS-CRF),we deploy CRF for the signer to rerandomize signature and deploy CRF for the Private Key Generator(PKG)to rerandomize public parameters.In addition,we design security game to prove that our IBS-CRF is against existence forgery under adaptive chosen message attack.Moreover,our protocol can achieve three basic characteristics of CRFs: maintain functionality,preserve security and resist exfiltration.Finally,We use pypbc library to run our protocols in a simulated environment to perform analysis.The results show that under different security levels,the increased computational cost of the reverse firewall accounts for almost only 1% of the total cost.In addition,with the security level increases,the percentage of increased computational cost becomes smaller.