# Research on Dynamic Searchable Encryption Method Based on Bloom Filter
## 1 Introduction  
In the age of big data, both individuals and businesses need to store large amounts of data. The identification information, preferences, and habits generated by users when using various applications are stored and analyzed. To protect the privacy of users, cloud servers fade in people's sight. As cloud servers are semi-trusted, unencrypted information being stored in a server can be insecure in two ways: In the first case, some malicious users will access the server. These malicious users will copy the information from the server, which will cause the user's information to be compromised. In the second scenario, the cloud server is honest but curious. In [PERSON] [1], the definition of an honest but curious server in the paper is: (1) storing outsourced data without modifying it; (2) honestly performing all operations such as searching and returning text data separately; and (3) attempting to learn the users' initial data. An honest but curious adversary is also defined as a legitimate server that will try to find out all the useful information from the obtained content but will not deviate from the set protocol in the communication channel mentioned by [PERSON] et al. [2]. As a result, users need to encrypt their important information and store it on cloud servers; otherwise, their information security will be at risk. For example, threat actors broke into Amazon's web servers and caused a breach of the sensitive information of 3.7 million users. The stolen data were then posted on various hacking forums for sale. In the same time frame, the FlexBooker cloud server was also compromised and the personal data of up to 19 millionusers were leaked. The investigation found that the company was using AWS S3 storage buckets to store data but had not implemented any security measures. It is therefore essential that data in cloud servers are kept encrypted. While encrypting the data keeps them from being compromised, it also prevents the cloud server from being able to manipulate the data. The reality is that users do not want to download data and process them again; they want to be able to add, delete, change, and check their encrypted data directly on the cloud server. As a result, the concept of symmetric searchable encryption (SSE) has been introduced and investigated. SSE enables the execution of keyword searches in ciphertext, one of the most basic data operations [3]. Users encrypt their private data and outsource them to a semi-trusted server, after which they send a search token to the server to perform a keyword search without revealing sensitive information [4; 5; 6; 7; 8]. Searchable encryption is divided into symmetric searchable encryption and asymmetric searchable encryption. In earlier research, symmetric searchable encryption was mainly studied in the static case. However, the static case is not applicable to practical work. Dynamic searchable encryption implements dynamic updates on the basis of the former. However, in order to improve the efficiency of the search, each of these options allows some information to be divulged within certain limits. The file injection attack was confirmed by [PERSON] et al. [9]. This attack is performed by injecting a relatively small number of files to learn a large portion of the keywords searched by the client. To resist this attack, forward security has received attention. [PERSON] et al. [10] proposed a definition of forward security for searchable encryption and proposed a scheme for a type of DSSE based on forward security. Later, [PERSON] et al. [11] proposed a definition of backward security and gave several schemes. [PERSON] et al. [12] propose a searchable solution that satisfies backward and forward security. However, this scheme is only applicable to individual users for searching their own data stored in cloud servers and is not applicable to practical applications. As most practical application environments are not closed, the implementation of symmetric searchable encryption always falls short of the requirements.