DOCUMENT PROCESSING METHOD AND SYSTEM

• US 20130159694A1
• Filed: 12/20/2011
• Published: 06/20/2013
• Est. Priority Date: 12/20/2011
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Chiueh, Tzi-Cker, Simha, Dilip
• Granted Patent: US 9,197,613 B2
• Time in Patent Office: Days
• US Class Current: 713/150
• CPC Class Codes: H04L 63/0478 applying multiple layers of encryption, e.g. nested tunnels or encrypting the content with a first key and then with at least a second key cryptographic mechanisms or cryptographic arrangements using a plurality of keys or algorithms H04L9/14
• CPC Class Codes: H04L 9/008 involving homomorphic encryption

Abstract

A document processing method and system are provided. A client divides at least one document into a plurality of document pages, and individually encrypts the document pages by a first key to obtain a plurality of encrypted pages. The client removes a part of words from the document pages to obtain a plurality of significant words, and individually encrypts the significant words by a second key different to the first key to obtain a plurality of encrypted significant words. The client records the encrypted significant words and a plurality of first index information in a significant word set (SWS), where the first index information indicates a page in the encrypted pages where the encrypted significant word comes from. Then, the client transmits the encrypted pages and the SWS to a remote server for storage.

Claims

1. A document processing method, comprising:

dividing at least one document into a plurality of document pages through a client;

individually encrypting the document pages by a first key to obtain a plurality of encrypted pages through the client;

removing a part of words from the document pages to obtain a plurality of significant words through the client;

individually encrypting the significant words by a second key different to the first key to obtain a plurality of encrypted significant words through the client;

recording the encrypted significant words and a plurality of first index information in a significant word set through the client, wherein the first index information indicates a page in the encrypted pages where the encrypted significant word comes from; and

transmitting the encrypted pages and the significant word set from the client to a remote server for storage.

2. The document processing method as claimed in claim 1, wherein the step of encrypting the document pages comprises:

individually compressing the document pages to obtain a plurality of compressed pages; and

encrypting the compressed pages by the first key to obtain the encrypted pages.

3. The document processing method as claimed in claim 1, wherein the first index information comprises a file name of the document and a page offset in the document.

4. The document processing method as claimed in claim 1, wherein the step of removing the part of words in the document pages comprises:

removing articles and basic grammar words from the document pages to obtain the significant words through the client.

5. The document processing method as claimed in claim 4, further comprising:

encrypting a keyword by the second key to obtain an encrypted keyword through the client when the client is to search the keyword;

transmitting the encrypted keyword from the client to the remote server;

searching the significant word set according to the encrypted keyword through the remote server, so as to obtain first index information corresponding to the encrypted keyword;

obtaining a target encrypted page from the encrypted pages according to the first index information corresponding to the encrypted keyword through the remote server;

transmitting the target encrypted page from the remote server to the client; and

decrypting the target encrypted page by the first key through the client.

6. The document processing method as claimed in claim 1, wherein the step of removing the part of words in the document pages comprises:

removing articles and basic grammar words from the document pages to obtain a plurality of original words through the client; and

stemming the original words to obtain the significant words through the client.

7. The document processing method as claimed in claim 6, further comprising:

stemming a keyword to obtain a root through the client when the client is to search the keyword;

encrypting the root by the second key through the client to obtain an encrypted keyword;

transmitting the encrypted keyword from the client to the remote server;

searching the significant word set according to the encrypted keyword through the remote server, so as to obtain an index information set corresponding to the encrypted keyword, wherein the index information set comprises a plurality of candidate encrypted significant words and a plurality of candidate index information;

transmitting the index information set from the remote server to the client;

decrypting the candidate encrypted significant words by the second key through the client to obtain a plurality of decrypted candidate words, so as to facilitate a user selecting a target significant word from the decrypted candidate words;

transmitting target index information corresponding to the target significant word in the candidate index information from the client to the remote server;

obtaining a target encrypted page from the encrypted pages according to the target index information through the remote server;

transmitting the target encrypted page from the remote server to the client; and

decrypting the target encrypted page by the first key through the client.

8. The document processing method as claimed in claim 7, wherein the step of transmitting the index information set from the remote server to the client comprises:

ranking the index information set according to a most frequently occurring keyword in the significant word set of the remote server; and

transmitting the ranked index information set to the client.

9. The document processing method as claimed in claim 1, further comprising:

removing a part of words from the significant words through the client to obtain a plurality of relevant words;

individually encrypting the relevant words by a third key different to the first key and the second key to obtain a plurality of encrypted relevant words through the client;

recording the encrypted relevant words and a plurality of second index information in a most relevant word set through the client, wherein the second index information indicates a page in the encrypted pages where the encrypted relevant word comes from; and

transmitting the most relevant word set from the client to the remote server for storage.

10. The document processing method as claimed in claim 9, wherein the step of removing the part of words from the significant words comprises:

defining a commonly used word set; and

removing words belonged to the commonly used word set from the significant words to obtain the relevant words.

11. The document processing method as claimed in claim 9, further comprising:

encrypting a keyword by the second key through the client to obtain a first encrypted keyword;

encrypting the keyword by the third key through the client to obtain a second encrypted keyword;

transmitting the first encrypted keyword and the second encrypted keyword from the client to the remote server;

searching the significant word set according to the first encrypted keyword through the remote server, so as to obtain a first search result corresponding to the first encrypted keyword;

searching the most relevant word set according to the second encrypted keyword through the remote server, so as to obtain a second search result corresponding to the second encrypted keyword;

transmitting the first search result and the second search result from the remote server to the client; and

comparing the first search result and the second search result through the client, wherein when the second search result is not a subset of the first search result, the remote server is confirmed to perform an unfaithful query processing.

12. The document processing method as claimed in claim 1, further comprising:

storing the encrypted pages to a database through the remote server; and

logging the encrypted significant words and the first index information of the significant word set in a global search index of the remote server.

13. The document processing method as claimed in claim 12, wherein the global search index comprises a key field and a value field, the key field records the encrypted significant words, and the value field records the first index information.

14. A document processing system, comprising:

a remote server; and

a client, connected to the remote server through a communication network, wherein the client divides at least one document into a plurality of document pages, and individually encrypts the document pages by a first key to obtain a plurality of encrypted pages, removes a part of words from the document pages to obtain a plurality of significant words, individually encrypts the significant words by a second key different to the first key to obtain a plurality of encrypted significant words, records the encrypted significant words and a plurality of first index information in a significant word set, and transmits the encrypted pages and the significant word set to the remote server for storage, wherein the first index information indicates a page in the encrypted pages where the encrypted significant word comes from.

15. The document processing system as claimed in claim 14, wherein the client individually compresses the document pages to obtain a plurality of compressed pages, and the client encrypts the compressed pages by the first key to obtain the encrypted pages.

16. The document processing system as claimed in claim 14, wherein the first index information comprises a file name of the document and a page offset in the document.

17. The document processing system as claimed in claim 14, wherein the client removes articles and basic grammar words from the document pages to obtain the significant words.

18. The document processing system as claimed in claim 17, wherein when the client is to search a keyword, the client encrypts the keyword by the second key to obtain an encrypted keyword, and transmits the encrypted keyword from the client to the remote server;

the remote server searches the significant word set according to the encrypted keyword to obtain first index information corresponding to the encrypted keyword, obtains a target encrypted page from the encrypted pages according to the first index information, and transmits the target encrypted page from the remote server to the client; and

the client decrypts the target encrypted page by the first key.

19. The document processing system as claimed in claim 14, wherein the client removes articles and basic grammar words from the document pages to obtain a plurality of original words, and the client performs stemming on the original words to obtain the significant words.

20. The document processing system as claimed in claim 19, wherein when the client is to search a keyword, the client performs stemming on the keyword to obtain a root;

the client encrypts the root by the second key to obtain an encrypted keyword;

the client transmits the encrypted keyword to the remote server;

the remote server searches the significant word set according to the encrypted keyword to obtain an index information set corresponding to the encrypted keyword, wherein the index information set comprises a plurality of candidate encrypted significant words and a plurality of candidate index information;

the remote server transmits the index information set to the client;

the client decrypts the candidate encrypted significant words by the second key to obtain a plurality of decrypted candidate words, so as to facilitate a user selecting a target significant word from the decrypted candidate words;

the client transmits target index information corresponding to the target significant word in the candidate index information to the remote server;

the remote server obtains a target encrypted page from the encrypted pages according to the target index information;

the remote server transmits the target encrypted page to the client; and

the client decrypts the target encrypted page by the first key.

21. The document processing system as claimed in claim 20, wherein the remote server ranks the index information set according to a most frequently occurring keyword in the significant word set.

22. The document processing system as claimed in claim 14, wherein the client removes a part of words from the significant words to obtain a plurality of relevant words;

the client individually encrypts the relevant words by a third key different to the first key and the second key to obtain a plurality of encrypted relevant words;

the client records the encrypted relevant words and a plurality of second index information in a most relevant word set, wherein the second index information indicates a page in the encrypted pages where the encrypted relevant word comes from; and

the client transmits the most relevant word set to the remote server for storage.

23. The document processing system as claimed in claim 22, wherein the client defines a commonly used word set;

and the client removes words belonged to the commonly used word set from the significant words to obtain the relevant words.

24. The document processing system as claimed in claim 22, wherein the client encrypts a query keyword by the second key to obtain a first encrypted keyword;

the client encrypts the query keyword by the third key to obtain a second encrypted keyword;

the client transmits the first encrypted keyword and the second encrypted keyword to the remote server;

the remote server searches the significant word set according to the first encrypted keyword to obtain a first search result corresponding to the first encrypted keyword;

the remote server searches the most relevant word set according to the second encrypted keyword to obtain a second search result corresponding to the second encrypted keyword;

the remote server transmits the first search result and the second search result to the client; and

the client compares the first search result and the second search result, wherein when the second search result is not a subset of the first search result, the remote server is confirmed to perform an unfaithful query processing.

25. The document processing system as claimed in claim 24, wherein the document includes a test text with at least a known keyword, and the query keyword includes the known keyword.

26. The document processing system as claimed in claim 14, wherein the remote server stores the encrypted pages to a database;

and the remote server logs the encrypted significant words and the first index information of the significant word set in a global search index of the remote server.

27. The document processing system as claimed in claim 26, wherein the global search index comprises a key field and a value field, the key field records the encrypted significant words, and the value field records the first index information.