This document proposes adding an encryption layer to Google Docs using a Firefox add-on in order to provide privacy and confidentiality for documents stored in the cloud. The add-on would intercept API requests to encrypt documents before uploading and decrypt them upon downloading. It discusses algorithms for encryption, including AES, DES, and Blowfish. The goal is to encrypt documents in the client before being sent or stored on Google's servers so their content remains inaccessible while maintaining usability and collaboration features of Google Docs.

1. Privacy for Google Docs: Implementing a Transparent Encryption Layer Lilian Adkinson-Orellana [email_address] GRADIANT, Galician Research and Development Centre in Advanced Telecommunication

2. Outline Introduction Firefox Add-on Using the secure Google Docs Conclusion and Future Work

3. Cloud Computing Distributed computing + distributed storage + virtualization. Advantages for users: Scalability. Ubiquity. Pay-per-use. No HW/maintenance cost. IaaS PaaS SaaS

4. Cloud Privacy Problems: Confidentiality: sensitive data exposed to the infrastructure provider . Privacy of the information: unauthorized access to private data by users. Loss of data: can users really trust on provider’s infrastructure reliability?

5. Document editing SaaS Maximum document size Maximum storage Price Real time collaboration Edit uploaded documents Type documents Google Docs 500K 1 GB free Yes Yes Text Spreadsheets Presentations Zoho - 1 GB free No Yes Text Spreadsheets Presentations Microsoft Office Live 25MB 500 MB free No No Text Spreadsheets Presentations ThinkFree 10 MB 1 GB 30 days trial Yes - Text Spreadsheets Presentations Feng Office - 300MB 30 days trial Yes Text Spreadsheets Presentations Adobe BuzzWord 10 MB - free Yes No Text Maximum document size Maximum storage Price Real time collaboration Edit uploaded documents Type documents Google Docs 500K 1 GB free Yes Yes Text Spreadsheets Presentations Zoho - 1 GB free No Yes Text Spreadsheets Presentations Microsoft Office Live 25MB 500 MB free No No Text Spreadsheets Presentations ThinkFree 10 MB 1 GB 30 days trial Yes - Text Spreadsheets Presentations Feng Office - 300MB 30 days trial Yes Text Spreadsheets Presentations Adobe BuzzWord 10 MB - free Yes No Text

6. Firefox Add-on Master password. Hidden indices: algorithm + options User index: information about encrypted and not shared documents. Shared index: information about encrypted and shared documents.

7. Firefox Add-on Channel listeners : intercept the communication with Google Docs servers. Google Docs API AJAX requests XUL (interface) + JavaScript. authentication, documents list, sharing permissions...

8. Firefox Add-on

9. Using the secure Google Docs: Changes in interface

10. Using the secure Google Docs: Encrypting a document

11. Using the secure Google Docs: Supported algorithms Name Block size Key size Security Speed Speed depends on key size? AES Advanced Encryption Standard 128 bits 128, 192, 256 bits Secure Fast Yes DES Data Encryption Standard 64 bits 56 bits Insecure Slow - Triple DES Triple Data Encryption Algorithm 64 bits 56-168 bits Moderately secure Very Slow No Blowfish - 64 bits 32-448 bits Moderately secure Fast No RC4 Rivest Cipher 4 64 bits 8-2048 bits Insecure Very fast No TEA Tiny Encryption Algorithm 64 bits 128 bits Insecure Fast No xxTEA Corrected Block TEA arbitrary, (min 64 bits) 128 bits Moderately secure Fast No

12. Using the secure Google Docs: Opening document w/o plugin

13. Conclusion and Future Work New security layer to protect Google Docs documents in a transparent way. Encryption in client-side: content of documents sent and stored in Google cloud servers are not accessible. Encrypted shared documents in development. Ciphered spreadsheets: need of server side support (operations performed in server-side).

14. Privacy for Google Docs: Implementing a Transparent Encryption Layer THANK YOU FOR YOUR ATTENTION!! Lilian Adkinson-Orellana [email_address]