Difference between revisions of "Encryption"

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== Read First ==
== Read First ==
* There are three main types of encryption algorithms relevant to our field. They are [[Encryption#Symmetric_Encryption | symmetric encryption]], [[Encryption#Asymmetric_Encryption | asymmetric encryption]] and [[Encryption#One-way_hashing | hashing]].  
* There are three main types of encryption algorithms relevant to our field. They are [[Encryption#Symmetric_Encryption | symmetric encryption]], [[Encryption#Asymmetric_Encryption | asymmetric encryption]] and [[Encryption#One-way_hashing | hashing]].  
* When transferring or sharing sensitive data, the data both need to be [[Encryption#Encryption_In_Transit | encrypted-in-transit]] and [[Encryption#Encryption_at_Rest | encrytped-at-rest]]
* When transferring or sharing sensitive data, the data both need to be [[Encryption#Encryption_in_Transit | encrypted-in-transit]] and [[Encryption#Encryption_at_Rest | encrytped-at-rest]]
* Encryption keys that can decrypt sensitive data must be shared using password managers
* Encryption keys that can decrypt sensitive data must be shared using password managers

Revision as of 16:51, 11 February 2020

In today's world of research, researchers regularly handle data, send it over the internet and store it in the cloud. At any point, especially when the internet is involved, the data is exposed to some risk. Keeping data safe and encrypted is hence a key component of IRB requirements and research ethics. Encryption should take place whenever dealing with sensitive data in any stage of research: from sampling and data collection to cleaning and analysis. This page discusses three different types of encryption and two different contexts when encryption is needed, in addition to some shorter related topics.

Read First

Three types of Encryption

There are three types of encryption useful to understand to safely operate in the digital world and to safely handle PII data. The difference between these three encryption types are under which circumstances the information can be decrypted and what key or password is needed to do so. The three types are:

  • Symmetric Encryption - Information can both be encrypted and decrypted and the same password is used when encrypting and decrypting
  • Asymmetric Encryption - Information can both be encrypted and decrypted but different passwords are used when encrypting and decrypting
  • One-way hashing - No password is used when encrypting, and there is no way decrypt anything that was one-way hashed

There are different algorithms for each of these different types of encryption, but most people do not need to know that there are different types of algorithms within these three types or what the difference between them are. Some of these algorithms are outdated and can easily be cracked, but unless you are someone implementing an encryption service of some sort, you do not need to know the details. Just google the service you want to use, and see if there are recommendations against using it, or ask someone you trust for which service to use. The recommendations given on this page are to services that have been recommended for a long time and is likely to keep being recommended.

Symmetric Encryption

In symmetric encryption you both encrypt and decrypt information using the same key. “Key” in this context is almost synonymous with password, but passwords are only one type of key. Advanced encryption may use such long passwords as key that the key becomes a file. This encryption is best suited for when you share a file both ways, meaning that both the sender and the receiver have equal access to the file. Sharing a file in syncing services like DropBox is an example of that.

Encrypting using symmetric encryption takes two inputs, the encryption key and the information to be encrypted, and the output is the encrypted unreadable version of the information. Decryption also takes two inputs, the exact same key used when encrypting and the encrypted unreadable version of the information, and the output is the original readable version of the information.

One extremely important aspect of symmetric encryption is that there is absolutely no way to decrypt the file if the key is lost. If you are using any service that claims to be able to recover information decrypted with symmetric encryption without the key, then they are either lying or that service is insecure. We recommend password managers as a secure long term storage of keys.

Anyone with access to both the encrypted file and the key can decrypt and read the information, so when third party services encrypt our data it is never secure enough if someone else than you and your team have access to the key. In research, when you have an IRB — which you should always have if you collect information on individuals — no-one but the people listed in the IRB should have access to the key. This is a central aspect when assessing if an encryption is good enough.

For example, services like DropBox and Amazon AWS offer automatic encryption on their servers. The encryption algorithms they are using are state-of-the-art and correctly implemented. However, in order to make it automatic, they keep a copy of the key, and as long as DropBox or Amazon are not included in your project's IRB, this is not good enough encryption. There is nothing wrong with them encrypting our files automatically, as it means that no-one but them can read the files (as long as they are not hacked), but we also need to exclude service providers when we protect sensitive data.

Symmetric encryption software - VeraCrypt

If we want to share a file with sensitive data over insecure services like e-mail or DropBox, we need to manually encrypt the file before we share it. We recommend the free of charge and open source software VeraCrypt. The software can be downloaded here and DIME Analytics has a user guide written with researchers as a target audience here.

VeraCrypt creates a “secure folder” that we will compare to a safe, and helps you generate a secure key that opens this safe. Just like a physical safe, anyone with access to the safe who also has the key will be able to access its content. You have to specify how much data the secure folder should be able to store, for example 100MB, and then that folder will take that amount of disk space on your computer regardless of being empty or full. This is again similar to a physical safe where it has the same size whether it is full or empty, which means that no hacker can tell if your secure folder has content or not. You cannot store more data than the limit you set when you create the secure folder, so if you run out of space, you must create a new secure folder with a bigger capacity and move the files there.

VeraCrypt decrypts the secure folder in such a way that is only decrypted as long as it is actively decrypted. This means that as soon as either you chose to stop decrypting it, VeraCrypt stops working, or your computer shuts down or lose power, the file is immediately encrypted again. When a secure folder is no longer decrypted it is always re-encrypted with the key that was used when it was initially created.

Once the secure folder is created you can share it empty or with content over insecure connections — like e-mail, DropBox, make it public on the web, etc. — as long as you share the key in a secure fashion. If you share the key in an insecure way, for example by putting it in an e-mail or in DropBox, it would be like shipping a physical safe with the key taped to the outside of it. The secure way to share the key is to use a type of software called password managers. Example of password managers are LastPass (closed source but World Bank approved) and BitWarden (open source but not approved for installation on World Bank computers). You use a password manager to safely share keys

You can use VeraCrypt for securing files also for when you are not sharing them with anyone. This is a good idea to do if you are store your tax papers, medical journals etc. on your computer. This is done the same way but you simply do not share the secure folder or the key with anyone. You still need the key yourself to decrypt the information later, so we strongly recommend you using a password manager as long term storage of keys even if you will not share them with anyone.

Is open source less secure? Open source is often said to be less secure, but that is not true if you use a software that has been around for a long time and has been examined and used by many cyber security experts. VeraCrypt fulfills both those requirements. When it comes to encryption, it is safer to use scrutinized open source software as VeraCrypt since you can be sure there is no “backdoor” implemented where there is a secret master key that can decrypt all files. Non-open source software are often forced by national intelligence agencies to implement such a “backdoor” so that government agencies get access to your encrypted data. But it is much more difficult to add backdoors in open source software without it being visible to everyone. So if a large community of users trusts an open source software, then that is your safest option.

Asymmetric Encryption

While symmetric encryption is like a safe where everyone viewing, modifying or adding content have must have the same key, asymmetric encryption is like the post office’s post collection box where anyone can add content but, only the post office staff has the key that can open and view the content. So instead of one key, in asymmetric encryption there is a public/private key pair. So in the post box example, there would be a public key to open the mail chute that anyone has access to and a private key that only the postal workers have that they use when they empty all the letters. While you do not risk compromising any data you have already collected by publishing the public key to the world, you should not do that as it would allow a malicious person to send you so much fake data to your collection box that it might be difficult to tell what data is real and what data is fake.

While the main benefit of asymmetric encryption is that you do not share the private key with anyone who sends you data, that is also the main limitation as it is only secure as a one-way communication. Another benefit is that it allows for a more automatic set-up as it is ok for servers to handle sharing of the public key. If you set up the private/public key pair and you want to share the private key with anyone so that they can also decrypt the data, then that private key needs to be shared using a password manager as in symmetric encryption.

Just as with symmetrical encryption, there is absolutely no way to decrypt files if the private key is lost. So even if you do not intend to share the private key with anyone, we still strongly recommend that you store it in a password manager for the future. The public key cannot be re-generated either if lost, but that doesn’t tend to be an issue, as you can create a new digital collection box and use the new private/public key pair.

Use case - sending data from the field

Asymmetric encryption is perfect for data collection as the data is only intended to flow one way, and we do not want to have to set up password managers on the devices used in data collection. By using asymmetric encryption we can allow the tablets to send data securely to the server without making it possible for anyone using a tablet to see what is already on the server. It is as if we are sending a post collection box where the tablet can safely store the information, and no one will be able access it apart from us, not even anyone using the tablet where the data was first encrypted.

Just as in symmetric encryption it is important that no-one who is not on the IRB has access to the decryption key, so the private key cannot be shared with any third party service we use for data collection. The private key should not be used to decrypt the data while it is still on the server, it should only be decrypted when or after it is downloaded. If you did not set up encryption or if you decrypted your data while it was still on the server, then the third party data collection service provider can read your data and they are most likely not listed on your IRB. Some data collation service providers let you view encrypted data in your browser without downloading it by providing the decryption key. It is perfectly possible to securely implement that without the service provider gaining access to the data, but make sure that you trust that service providers ability to do so.

When you download the data you should decrypt it with the private key, and then put it in a folder that is encrypted using symmetric encryption. The reason we shouldn’t keep using the asymmetric public/private key pair is that we need different keys to view and add data and there is no practical way of modifying data already encrypted. In symmetric encryption the same key is used to view, modify and add data, which is much more practical when you start working with your data on your computer.

One-way hashing

This type of encryption is quite different to symmetric and asymmetric encryption, as anything hashed (encrypted with one-way hashing) is impossible to decrypt, or un-hash. There are use-cases where it makes sense to hash our data, but encryption is not one of them as there is no way of decrypting data that has been hashed. The reason why we are brining it up is that it is very central to secure online activities, especially passwords handling, and that is related to encryption and data security.

While it is impossible to un-hash anything, the same piece of information is always hashed the same way as long as the same hashing algorithms is used. This means the output or the “hash” is the always the same if the input is the same. So, when the input to a hashing algorithm is the same, then the output is always the same. This also means that if the output to a hashing algorithm is different, then the inputs used could never have been the same.

There is no practically possible way to calculate the input based on the output even if you know exactly which algorithm that was used. The input to output conversion takes milliseconds but the output to input conversion would take millennia if attempted, rendering it practically impossible even though it is theoretically possible. Good hashing algorithms are implemented so that two similar inputs still has widely different outputs so there is no way to guess the input just that the output is similar to another output you know the input for. Also, if you hashing the output again, you do not get to anything similar to the input. In fact, re-hashing a has 10 times is a common trick to make it even more impossible to crack a hash.

Example of use-case of one-way hashing

When you create an account on any service like Facebook.com or DropBox.com they take your password and use it in an one-way hashing algorithm, and then only save the output, or the hash, in their data base. If their servers would be hacked, or if their data base engineers were undercover hackers, all they would see is the output of the one-way hash algorithm and not the input, i.e. your password. Every time you log in to your account, your password will be put into the same hashing algorithm and the output will be compared to what they saved in their data base when you created your account. If the outputs or hashes are the same, then they know that you used the same password both times, even though they never saved your password when you signed up.

This is not difficult to implement, so any service that does not hash user passwords before saving them is extremely insecure and should always be avoided. No web-company will ever show you their database but here are examples on how you can know that they did not hash your password before storing it. If you ever encounter any of the scenarios below, stop using that service and report it on cyber-security forums immediately.

  • They are able to send you the password if you forget it. Secure services will never be able to send you your password, instead they send you a temporary password or a password rest link
  • Anyone in customer support is able to tell you your password, or they say that they can see it on their screen

Example of weaknesses of one-way hashing. Common input leads to common output. Very common passwords like “Password1”, “qwerty” or “12345678” have very well known hashes, and hackers have already calculated and published the hashes for hundred of thousands of common passwords. So if someone hacks into a database and you have used “12345678” as your password, then your hash is quickly identified as a known hash, and the hacker immediately knows your password. In addition to common long-ish passwords like “Password1”, hackers has already calculated all hashes for all possible combinations of passwords up to a few letters long. That is why services require you to have password of a certain lengths, and use symbols and numbers, as combination of only letters is the first thing hackers calculate as they cover all combinations of longer and longer passwords.

Encryption in Transit and at Rest

Encryption in Transit

Almost all internet traffic is encrypted in transit, but your data is completely open for anyone to view when it is not used. This means that traffic not encrypted in transit can be read by the internet service provider of both the sender and the receiver and governments of the geographic location of both the sender and the receiver. Every single request on the internet passes through multiple web-server, and in many cases, especially in international internet traffic, the request passes through many web-servers relaying internet traffic. Traffic not encrypted in transit can be read by all those web-servers, and often stored in log-files. Hackers often poses as fake web servers online just sitting there waiting for un-encrypted traffic that they can read and perhaps exploit.

While the consequences of not encrypting data in transit cannot be underestimated, it is luckily straightforward to implement and all well-established service providers we use (i.e. Survey Solutions, SurveyCTO, DropBox, OneDrive) have already implemented this. However, when using less established services, confirm that they use encryption in transit by looking at the internet address. If the service provider uses secure transfer methods, you will see https:// in the internet address instead of simply http://. Data sent from an API using http:// can easily be spied on. Modern browsers warn the user if the response was not signed in the first place or if the signature could not be confirmed. This is usually called that the “connection is insecure", “a secure connection could not be established” or something similar. You should never send passwords, credit card information or any other sensitive information if you get any of those warnings or if the URL starts with http:// instead of https://.

Secure https:// use asymmetric encryption to secure internet traffic. When you communicate with an internet server over https://, you first send a message with no sensitive data to the server saying that you are ready to send something in a secure way. The server then creates a public/private key pair and sends the public key back to you. Your browser then encrypts your data using the public key and sends it to the server. The server then decrypts it with the private key, which is kept secret as it has never left the server. That specific public/private key pair is then discarded to never again be used. This is repeated thousands of times each time you use the internet. All browsers handles this automatically and it is done in milliseconds, so you have used this millions of times in your life and probably a few hundred times already today.

Note that encryption in transit has nothing to do with a service requiring a username or password. While a password-protected resource can only be requested by someone with the correct password, once it is in transit to the authorized user, the servers handling it can still see it if it is not encrypted.

Encryption at Rest

Encryption at rest means that the data stored on the server is scrambled in such a way that it is unreadable by anyone – even if they can access the file directly. If the data is not encrypted at rest, then anyone with access to the server can read that data (including, for example, the host company and your team’s administrators). If the data is encrypted at rest, however, the data is impossible to read even if someone gained unauthorized access to the database or the files where the data is stored. Encryption at rest can use either symmetric encryption or asymmetric encryption depending if the person or device uploading the data to the server is meant to also be able to read the data.

Encryption at rest is not as easy to implement as encryption in transit. The main reason for this is that in encryption in transit we trust the server to handle the decryption key as it is used for such a short time and thereafter deleted. When we encrypt data at rest we need the key over a long time as we might access the data over months or years, and then the web server handling incoming and outgoing requests is not a safe place to store the key. Instead we need to manually set this up using an encryption software or use features for this in third party software providers.

The encryption we set up needs to make sure that we are in full control of the decryption key. If they key gives access to sensitive data we need to make sure that key is not exposed to anyone who is not listed on the IRB. We want to make sure that the data is encrypted before it is sent to the server where it will be encrypted at rest. We cannot trust the web server to do this for us, as the web-server can be compromised and then it is too late to encrypt it by the time it reaches that server. When we manually encrypt the data before sending it, and carefully share the key, then any part of the internet infrastructure can be compromised and all that the hackers can see is encrypted information which without the key is unreadable gibberish.

Other recommendations

Encryption decryption keys

The following principles always hold for key:

  • Keys can only be created once. Any services that claim to be able to re-store lost decryption keys for you are not safe: this is equivalent to them having your password. This either means that the data is not properly encrypted or that they saved a copy of your decryption key that gives them full access to your encrypted data.
  • If you lose one key in a public/private key pair you need to recreate a new pair. Anything encrypted with the original public key can never be decrypted with anything but the original private key
  • Most services provide a convenient way of decrypting your data, but if you are not asked for the key every time the data is viewed or decrypted, then your data is not encrypted properly.

Password and Key Management

When using public/private key pairs, you need to keep a lot of keys safe and well-organized. You can never store, organize, or transfer them using unsecure methods like email or Dropbox. DIME Analytics recommends using password managers as a convenient and safe solution for storing private keys and passwords. While there are many password managers out there, DIME Analytics recommends LastPass, whose free, basic tier satisfies all requirements a research team would ever need.

Password managers like LastPass allow you to store small text files or string fields, as private/public key pairs sometimes come in file format. LastPass can save keys as small text files or as strings for you as secure notes, which you can also use for other important information, like noting to which encryption container the private key pertains. Password managers like LastPass can also help you randomize passwords so that your passwords are impossible-to-guess, long strings. Since the password manager store and remembers this password for you, you will not need to memorize it and you can easily have a different long random string for each account you have.

Some password managers allow you to share passwords across accounts. This is a great feature: if one person updates the password, then everyone else has the updated password in their account immediately. Password sharing is sometimes a paid feature. One way around paying is for the research team to create one account and share access to that account. However, make sure to not share this account to more people than those who really needs it.

Encryption with SurveyCTO Data

When programming questionnaires in SurveyCTO, use the key generator to create a public-private key pair for your data with the name of your intended survey. These will download two files to your laptop: these are the keys. Create an encrypted survey with the public key. Then put the keys in the vault via LastPass or VeraCrypt. Note that you will need the private key for the form data download. Store encrypted data iefolder’s EncryptedData folder. Note, however, that while iefolder makes the folder, it does not encrypt it.

In your first cleaning do-file, de-identify the PII data to create a de-identified dataset. If you’re using Veracrypt, the veracrypt command allows Stata to call for VeraCrypt to mount the drive. Then you have to manually enter the password anytime you run the do-file. The first cleaning file should move the non-PII version of your data to the regular data folder.

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This article is part of the topic Data Security

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