Searchable symmetric encryption $($SSE$)$ is a form of encryption that allows one to efficiently search over a collection of encrypted documents or files without the ability to decrypt them. SSE can be used to outsource files to an untrusted cloud storage server without ever revealing the files in the clear but while preserving the server$$s ability to search over them. Keyword search using an SSE scheme can be illustrated in Figure $1.$

Figure $1.$ Create Search Token, Search, Decrypt Retrieved Documents

Suppose you wish to store the following five documents with given keywords on a cloud server using SSE:

Document $1$: $\{$School$,$ University, Lecture$\}$

Document $2$: $\{$Tutorial$,$ Assignment$\}$

Document $3$: $\{$University$,$ School, Tutorial$\}$

Document $4$: $\{$Team$,$ Scores$\}$

Document $5$: $\{$School$,$ Codes$\}$

Assume that the secret key for token generation: $1=$ your student ID and the secret key for encryption key generation: $2=$ your email address, and the Pseudorandom Function $($PRF$)$ is HMAC$-$SHA$1$ and the encryption algorithm is Advanced Encryption Standard $($AES$)$ with $128$ bits key size.