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If you are collecting sensitive, personally-identifiable data, then you will want to encrypt it so that your authorized team members are truly the only ones with access to that data. The model of encryption supported by SurveyCTO is the following:

  1. As soon as a surveyor marks a filled-out form as "finalized," the form's contents will be encrypted using your public encryption key – except for those fields explicitly marked as publishable (those fields with a "yes" in their publishable column). Fields explicitly marked as publishable are left unencrypted so that they can be conveniently published to cloud services or directly downloaded from the server.
  2. From that point forward, the form can no longer be edited because not even the device on which the form was filled can decrypt it (the "device" in this case can be a mobile device or the SurveyCTO server, in the case of web forms).
  3. Whenever form data is transmitted via a 3g or other Internet network, it is encrypted in transit using SSL. This is true for all form data regardless of whether the form itself is configured to be encrypted – so, in a sense, encrypted forms are doubly-encrypted (once with your public key, and then again with SSL).
  4. The SurveyCTO server stores the form data, but it remains encrypted and therefore unreadable by the server (and by anyone who might conceivably compromise that server, legally or otherwise). (Again, though, fields explicitly marked as publishable will remain readable by the server.)
  5. When the form data is downloaded by an end-user using SurveyCTO Desktop, the Data Explorer, or the Download option on the Export tab, it is again doubly-encrypted, with both your public key and the SSL protocol used for secure data transmission.
  6. Desktop, the Data Explorer, and the server download option all store local backups of the form data in local storage, but it remains encrypted and therefore unreadable.
  7. The end-user who downloads the data can use your private encryption key to decrypt and read that data. For added security, this user may choose not to store that private key on an Internet-connected computer; the user may use Desktop to transport the data to a secure "cold-room" computer, and only then decrypt the data, export it for further processing, and begin the analysis.

The key thing is that the SurveyCTO model of encryption relies on you generating the encryption keys with which data is encrypted; this assures that you and you alone are able to access your data. So the first step is to generate your own public/private encryption key pair, which you can then use to encrypt all of your sensitive forms.

To create a new key pair, navigate to the Design tab, scroll down to the Your forms and datasets section, click the Tools option at the very top of the section, and then click the Create new key option. Once you click to open the key generator into a new browser window, you can disconnect from the Internet if you wish to ensure that the key pair is generated and known only locally, on your computer. In the key generator, you will name the key pair, then "download" the private and then public key files ("download" being in quotes because all of this is happening, for privacy, locally in your web browser and not on our server). By default, the key files are named keyname_PRIVATEDONOTSHARE.pem and keyname_public.pem.

keyname_public.pem is the public key used to encrypt data. As the name suggests, it is public – so you don't need to worry about safeguarding it.

keyname_PRIVATEDONOTSHARE.pem is the private key used to decrypt data. This private key you want to guard very closely. In fact, you may want to generate the key pair on a "cold room" computer that is extraordinarily secure (e.g., disconnected from the Internet) and never have other copies of the private key in less secure locations. (To generate a key pair on a cold-room computer, run SurveyCTO Desktop and select Create encryption key pair... from the Offline form tools menu.)

While you do want to be very careful with your private key, make sure that you do not lose it. The private key is your only way to decrypt data. If you lose it, you will also lose the ability to decrypt data. Thus, you will need some very secure way to back up or otherwise safeguard your private key against loss. If you have it only on a cold-room computer, for example, and that computer fails – how will you decrypt your data?

Once you have a key pair, you are ready to configure your forms for encryption. To start a new encrypted form, just click + and then Start new form in the SurveyCTO server's Design tab, enable the Advanced options, and mark the checkbox to indicate that you want the form to be encrypted; in the next step, upload your public key file when prompted (not the private key: that you never upload to anybody). Your new form will then include, on its settings worksheet, a copy of your public key. That will then be used to encrypt all finalized forms.

You will design and deploy these encrypted forms just as you do non-encrypted forms, and surveyors will fill them out and submit them in the usual way. The only real difference will come in when you are ready to publish, download, or analyze your data.

Accessing your encrypted data will require use of your private key. When needed, the server console will prompt you for your private key file. When using SurveyCTO Desktop to export your encrypted form's data to local export files, you will need to specify the location of your private key: use the Browse button to point Desktop to where it resides on your local system. Without that private key, Desktop cannot decrypt and export your data. (It can download the data and store it locally, but it cannot decrypt or export it.)

If you are keeping the private key only on a cold-room computer, follow these steps to download, decrypt, and export your data:

  1. On an Internet-connected computer, run SurveyCTO Desktop with Server as the data source and External drive as the data destination. When you download data, it will download and sync to an external hard drive (either a thumb drive or an external hard drive).
  2. Eject the external drive, bring it to the cold-room computer, and plug it in.
  3. Finally, run SurveyCTO Desktop on the cold-room computer with External drive as the data source and Export as the data destination. Also tell Desktop where to find the private key file using the Browse button.

If you want to publish some parts of an encrypted form to a server dataset (e.g., to feed directly into other forms) or publish some parts to the cloud (e.g., to monitor key indicators via a Google Sheets dashboard), you will need to explicitly mark some fields as publishable so that they will remain unencrypted (by putting a "yes" in their publishable column). Those fields will still be encrypted in transit, but they will be technically readable by the SurveyCTO server. (Please note, however, that file attachments – like photos or audio recordings – are always encrypted: even if they are marked as publishable, they cannot be accessed without the private key.)

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