The invention relates to a multi-keyword
plaintext and
ciphertext retrieving method and device oriented to
cloud storage and relates to the field of information safety. The method includes the following steps that firstly, a
client terminal performs
lexical analysis according to inquiry statements and generates
plaintext keywords; secondly, a corresponding user index
encryption key is obtained according to a main key bound with the identity of a user, and the
plaintext keywords are encrypted with the
encryption algorithm of the index
encryption key, and
ciphertext keywords are generated; thirdly, multi-keyword
ciphertext retrieving is performed on a ciphertext index in a
cloud storage server according to an inquire tree generated by the
client terminal, and retrieved
data element information and retrieved relevancy scores undergo inquiry result merging and sequencing; fifthly, inquiry result merging and sequencing are performed in the
cloud storage server with the same method; sixthly, a unified sequence result is sent to the
client terminal, and an inquiry result is displayed to the user. According to the multi-keyword plaintext and ciphertext retrieving method and device oriented to the cloud storage, a
key management scheme which is higher in safety degree is provided, plaintext and ciphertext united retrieving can be supported and multi-keyword retrieving can be provided.