Research And Implementation Of Wideband High Resolution Frequency Synthesizer

With the rapid development of cloud computing,increasing data are stored on cloud servers,and the security of these data has become a widespread concern.Proxy re-encryption(Proxy Re-Encryption,PRE)technology is a natural application for cloud computing,using proxy re-encryption technology,ciphertext stored on untrusted cloud servers can be safely shared.Therefore,the research of high efficiency,multi-function and high security PRE scheme has gradually become an important topic.Identity-based proxy re-encryption scheme(Identity Base PRE,IB-PRE)is an important extension of the traditional PRE scheme.In IB-PRE,semi-trusted proxies are allowed to convert the password encrypted based on Alice identity into Bob's decryptable ciphertext,and in the process,the proxy cannot obtain the content of the ciphertext.Because the encryption algorithm of IB-PRE scheme is based on user identity information rather than user public key,compared with traditional PRE scheme based on traditional private key infrastructure(Public Key Infrastructure,PKI),IB-PRE scheme does not need to manage a large number of public key certificates,so it has been widely concerned by the cryptography field.IB-PRE defines a variety of functional attributes,such as unidirectionality,multi-hop,anti-collusion and so on.Some researchers embedded conditional parameters into IB-PRE and defined conditional IB-PRE scheme(Conditional IB-PRE,IB-CPRE).However,few IB-PRE schemes have achieved high efficiency and security with multiple functions at the same time.Driven by actual demand,this paper proposes the following two schemes based on bilinear mapping.1.For the first time,an uniderectional multi-hop IB-PRE scheme with fixed ciphertext length and anti-collusion attack is proposed.At the same time,the CPA(Choose Plaintext Attack)security proof of the scheme is formalized in the standard model.Compared with the existing work,the proposed scheme has more advantages in computing and storage overhead.2.An efficient unidirectionality multi-hop IB-CPRE(Unidirectional Multi-hop IB-CPRE,UMH-IB-CPRE)scheme is proposed for the first time.We constructed the first IB-CPRE scheme with unidirectionality multi-hop feature and constant ciphertext length under the standard model.Moreover,the scheme is non-interactive and anti-collusion.In addition,by adding strong unforgettable signature,the scheme achieves CCA(Chosen Ciphertext Attack)security under the standard model,and gives the security proof.3.Based on the UMH-IB-CPRE scheme proposed above,a secure data sharing scheme for cloud computing environment is proposed.Specifically,we give the security implementation method of user data transmission and storage for cloud stor age system model,and give the security analysis.