With the widespread applications of Massive Open Online Courses （MOOCs） platforms， an effective method is needed for personalized course recommendation. In view of the existing course recommendation methods， which usually use the course learning records to establish the overall static representation for users’ learning interests， while ignoring the dynamic changes of learning interests and users’ short-term learning interests， a Hierarchical and Phased Attention Network （HPAN） was proposed to carry out personalized course recommendation. In the first layer of the network， the attention network was used to obtain the user’s long- and short-term learning interests. In the second layer of the network， the user’s long- and short-term learning interests and short-term interaction sequence were combined to obtain the user’s interest vector through the attention network， then the preference value of the user’s interest vector with each course vector was calculated， and courses were recommended for the user according to the result. Experimental results on public dataset XuetangX show that， compared with the second best SHAN （Sequential Hierarchical Attention Network） model， HPAN model has the Recall@5 increased by 12.7%； compared with FPMC （Factorizing Personalized Markov Chains） model， HPAN model has the MRR@20 increased by 15.6%. HPAN model has better recommendation effect than the comparison models， and can be used for practical personalized course recommendation.

Ring signature is widely used to solve the problems of user identity and data privacy disclosure because of its spontaneity and anonymity； and certificateless public key cryptosystem can not only solve the problem of key escrow， but also do not need the management of public key certificates； certificateless ring signature combines the advantages of both of the above mentioned， and has extensive research significance， but most of the existing certificateless ring signature schemes are based on the calculation of bilinear pairings and modular exponentiation， which are computationally expensive and inefficient. In order to improve the efficiency of signature and verification stages， a new Efficient CertificateLess Ring Signature （ECL-RS） scheme was proposed， which used elliptic curve with low computational cost， high security and good flexibility. The security statute of ECL-RS scheme stems from a discrete logarithm problem and a Diffie-Hellman problem， and the scheme is proved to be resistant to public key substitution attacks and malicious key generation center attacks under Random Oracle Model （ROM） with unforgeability and anonymity. Performance analysis shows that ECL-RS scheme only needs （n+2） （n is the number of ring members） elliptic curve scalar multiplication and scalar addition operations as well as （n+3） one-way hash operations， which has lower computational cost and higher efficiency while ensuring security.