II. DISCUSSION ON ENCRYPTION PROGRAMS

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1 Overview of Dropbox Encryption in Cloud Computing S.Raju 1 K.Santhi 2 S.Latha 3 1Professor and HOD, Department of IT, Mahendra Engineering College, Namakkal, India. 2 &3 Assistant Professor, Department of IT, Mahendra Engineering College, Namakkal, India. Abstract: Cloud computing has been envisioned as the next-generation architecture of IT. Drop box is one of the most popular cloud storage services in the world. Dropbox was arguably the first cloud storage service that promoted mass adoption thanks to a referral program and an intuitive interface. Dropbox cemented its place on our mobile devices with a range of capable apps, and developers have figured out ways to use it for all kinds of purposes: server backups, Google Docs sync and browser add-ons, to name just three. But with Dropbox, there s one challenge: privacy. In this paper we discuss the overview of various encryption algorithms or programs for drop box encryption. Index Terms: cloud computing, Dropbox, cloud storage, privacy, encryption program I. INTRODUCTION The cloud is a convenient place to back up and store files, but you should hesitate before uploading that sensitive data, whether you re using Dropbox, Google Drive, or SkyDrive. Sure, your files may be encrypted in transit and on the cloud provider s servers, but the cloud storage company can decrypt them and anyone that gets access to your account can view the files. Client-side encryption is an essential way to protect your important data without giving up on cloud storage. Encryption does add some complexity, however. You can t view the files in the cloud storage service s web interface or easily share them. You ll need your encryption tool to decrypt and access your files. Encryption is ideal for sensitive files, but you don t have to encrypt everything. Be sure to use a strong passphrase when setting up encryption, too. II. DISCUSSION ON ENCRYPTION PROGRAMS SpiderOak is not just an encryption program. It combines client-side encryption with 2 GB of free cloud storage (more storage is availale for a fee). In other words, you don't need a separate cloudstorage service. SpiderOak also provides sync between PCs and portable devices in addition to backup. In sum, SpiderOak provides encryption backup, sync and storage space. Backup and sync can be automatic. Your files are unencrypted on all your synced devices, but are always encrypted for transmission and storage in the cloud.you can use SpiderOak for as many folders as you like. Of course you can use up the free 2 GB pretty quickly, but it is inexpensive to get more. Wuala is similar to SpiderOak, and also provides selective sharing by file or folder. They offer a more-generous 5 GB free storage. I had intended to use Wuala, but it requires Java, which exposes your PC to a seemingly perpetual string of serious vulnerabilities. Wuala uses AES- 256 for encryption, RSA 2048 for signatures and for key exchange when sharing folders, and SHA-256 for integrity checks, which is good in principle, but keep in mind that AES is an NSA "approved" algorithm. Their servers are in Switzerland, Germany, and France, which may offer you more privacy. Tresorit is the latest entry in the "client plus cloud" encryption service arena, with a free 5 GB plan. The Tresorit interface is gloriously simple, and they go to great lengths to explain their approach to encryption. They even have an impressive analysis of why they doubt that Tresorit has been hacked. Cloudfogger provides client-side encryption for files in any folders (up to 5 for the free version) you want to select. It integrates seamlessly with Dropbox, SkyDrive, Box, Google Drive, or any other cloud storage service. The cloud only contains encrypted files since that is the only kind that normally exist in any folders you "fogg". 27 Techscripts

2 The files are visible locally as unencrypted files when you are signed in to the Cloudfogger app. Cloudfogger implements these two views - internal and external - using on-the-fly encryption. Folders that you "fogg" (auto-encrypt) serve as encrypted file containers. SafeMonk is similar in operation to Cloudfogger, but quite a bit simpler to use. It is a bit unsual in that it uses public/private encryption instead of shared key. That enables a very flexible sharing capability that works on a folder-by-folder basis. SafeMonk presents the same hazard that many cloud encryption products do. If you copy a file to the SafeMonk folder without SafeMonk running it will be unencrypted on your computer and in the cloud. BoxCryptor and Viivo provide most of the same functions that Cloudfogger does. They are integrated with the file-system in a different way though. Both use an encrypted virtual-drive interface that is linked to an ordinary folder. They encrypt a single folder, and augment it with the virtual-folder overlay to give cleartext access. With this approach, you work directly with an unencrypted local files, which is faster, but not as secure against local attack. TrueCrypt is a top-rated product for most uses, but there is a potential backup trap when it is used for files that will be synced or stored in the cloud. Encryption programs that create encrypted "volumes" (files that contain encrypted files) do not change the size of the volume (container file), and often - intentionally - do not change the modified date of the volume, even though files in the volume have been changed or added. TrueCrypt is an example of an encryption program that does not change the modified date of volume files (encrypted file container). III. CREATE A TRUECRYPT CONTAINER TrueCrypt is a do-it-yourself method of encryption. With TrueCrypt, you can create an encrypted file container and save it to your Dropbox folder. This file is a big, encrypted blob no one can see the inside of it without your passphrase. TrueCrypt can mount the encrypted file container as a drive letter or fodler on your computer. Files you place inside the special TrueCrypt drive or folder will be encrypted and stored inside the TrueCrypt file container in your Dropbox folder. Our guide to creating and mounting an encrypted file container with TrueCrypt will walk you through the process. Figure 1: TrueCrypt Volume Creation Wizard Dropbox can synchronize only the changed portions of large files, while Google Drive and SkyDrive can only synchronize entire files (as far as I can tell). This means that, if you have a 2GB TrueCrypt drive and change a small file in it, Dropbox will upload a small portion of the TrueCrypt file, while Google Drive and SkyDrive will re-upload the entire 2GB file. Use An App BoxCryptor is an easy-to-use encryption solution. In spite of its name, you can use it with any cloud storage service, not just Dropbox. BoxCryptor creates a special subfolder in your cloud storage folder in this folder, BoxCryptor stores encrypted versions of the files you add to a special BoxCryptor drive letter. BoxCryptor also has mobile apps, allowing you to access your encrypted files on the go. The Android app supports Dropbox and Google Drive, with SkyDrive support on the way. The ios app 28 Techscripts

3 will also receive Google Drive and SkyDrive support in the future. The free version of BoxCryptor is limited to 2GB of encrypted files. Figure 2: Use of BoxCrypt Application Figure 3: BoxCryptor with Mobile Applications Cloud Fogger, which we ve covered in the directory, and Secret Sync are other, competing services which work similarly. Switch To An Encrypted Service All the other options here are ways of grafting client-side encryption onto a cloud storage service that doesn t natively support it. Instead, you could opt for a cloud storage service that includes clientside encryption. SpiderOak and Wuala are good options. These services encrypt and decrypt your data locally the services themselves have no idea what data you re storing; they couldn t view it if they wanted to. Figure 4: Switch to an Encrypted Service Check out our full walkthrough of SpiderOak for more information. It s a bit more complicated to set up than Dropbox and similar services, but it offers more flexibility for example, you can synchronize any folder on your computer. Encrypt Individual Files 29 Techscripts

4 If this all seems a bit much for you, you can just encrypt a handful of important files with a utility on your computer. You ll need the utility to decrypt and access your encrypted files in the future in the past, including creating an encrypted archive file. Figure 5: Encrypted Individual Files (Add to Archive) Set Up EncFS On Linux EncFS is an open-source option for Linux users. It s exactly what it sounds like an encrypted file system. It works similarly to BoxCryptor (in fact, it inspired BoxCryptor) EncFS creates a special folder that contains encrypted versionsof your files. EncFs transparently decrypts and provides access to these files in another folder. You work with your files in this folder, and EncFS stores the files in encrypted form in your cloud storage folder. Figure 6: Setup EncFS On Linux It s a bit more complicated to set up, involving terminal commands. But, unlike the free version of BoxCryptor, it doesn t limit the amount of files you can encrypt. We ve got a guide to setting up EncFS on your Linux system, if you re interested. Using TrueCrypt to Protect Your Data in Dropbox TrueCrypt is free, open source disk encryption software and you can get it for Windows, MacOS X and Linux. It s practically a standard for desktop data encryption and even Dropbox itself recommends using TrueCrypt to its users. One of the best features of TrueCrypt is that you can create an encrypted volume and place it into your Dropbox. Everything that you place inside that volume will be encrypted. If somehow anybody gets its hand on that volume, without your master password, the file will be useless, while still protected. IV. HOW TO USE TRUECRYPT TO ENCRYPT YOUR DROPBOX DATA The first step is to download and install TrueCrypt. Run the application and follow these few steps. 30 Techscripts

5 Figure 7: Step1 download and Install TrueCrypt Click the Create Volume button to start the volume creation wizard. Figure 8: Step2 create volume button Select the option to create an encrypted file container. Figure 9: Step3 select create an encrypted file container Choose Standard TrueCrypt volume. Now choose desired size of the container (should be smaller than your Dropbox account, obviously). Figure 10: Step4 select standard TrueCrypt Volume This is important - when asked where your container should be placed, navigate to your Dropbox folder (or any folder inside the Dropbox) and enter the filename of the container. That will be the name of the actual encrypted container in your Dropbox. You can open up your Dropbox to see the file inside. It will already take up the amount of space you dedicated to it, although it s still empty. 31 Techscripts

6 Put Your Files inside the Encrypted Volume To use this encrypted volume you just created, you ll need to mount it. Mounting a drive means to tell your computer that this-or-that file should actually be treated as a drive, just like any other hard drive or USB flash memory stick. Figure 11: Step5 Put your files inside the encrypted volume Open up TrueCrypt again and click Select File. Find your TrueCrypt volume file in your Dropbox folder and select it. Click Mount or Auto-Mount and enter the password you created earlier in the steps. Figure 12: Step 6 Hard Disk Drives Your encrypted file will now be visible in your computer as an additional hard drive and whatever you put inside will be encrypted and uploaded to Dropbox, where it will be encrypted again. V. CONCLUSION The difference between BoxCryptor and TrueCrypt is the method of encryption. While BoxCryptor encrypts files one by one, TrueCrypt encrypts all of your files in a bundle (a container), and that is then sent to the cloud storage provider. In practice, both work well. But with TrueCrypt, your files are bundled. If you need mobile device support, go with BoxCrypt; if you want to guarantee the software is free for life, TrueCrypt is the better option. REFERENCES 1. LI Wei (China Mobile Group Design Institute Co.,Ltd.,Beijing ,China);Study and exploration on cloud computing security[j];telecom Engineering Technics and Standardization; U Gang (School of Software Engineering of Hust Wuhan );Cloud Computing and Cloud Security[J];Information Security and Technology;2011-Z1 Types of cloud Brokers that can save the cloud 3. R. Sherman Distributed systems security Computers & Security, 11 (1) (1992) 4. A survey on security issues in service delivery models of cloud computing, S. Subashini, V. Kavitha 5. Key Security Technologies on Cloud Computing -Zhang Yunyong, Chen Qingjin, Pan Songbai, Wei Jinwu. 32 Techscripts