Introduction
We at Dagning take the security of your data very seriously. We know that the data a BRF styrelse deals with is sensitive, and that all members of the board are bound by secrecy. That's why, when you start using Dagning, the app generates a random four-word passphrase for you. This passphrase is used to create a key that encrypts all the data you store in Dagning, so that nobody, not even us, can read it.
What is data encryption?
Data encryption means that your files, messages and notes are saved in a form that nobody can freely read. Encryption has a long history, reaching back to ancient times. One of the most basic methods is the Caesar Cipher, where each letter is moved a fixed number of steps, so that DAVID becomes EBWJE, each letter replaced by the one directly after it. Such a method is easy to break, though, especially with modern computers. Even if we shifted each letter by 12 places instead of 1, a computer can check the limited number of combinations almost instantly, which makes this method far from secure. As computers grew faster, new algorithms were invented to make encryption harder to break.
Why is encryption required?
Because your data is sensitive and often personal. Boards deal with matters related to the people who live in the BRF, and can in some cases discuss legal or financial issues, or disputes between neighbours. This data needs protection, and each member of the board is obliged to keep secrecy when discussing such matters. If these discussions are intercepted by a malicious actor, it can lead to serious consequences for everyone involved. One such case was the SportAdmin breach, which exposed the personal data of over two million people, including Prince Carl Philip. When data was mostly kept on paper, a breach required physical access to the documents and was limited to a single BRF. Today, with digital tools storing data in the cloud, a hacker can potentially reach the data of many föreningar at once.
Are there any cases where encryption wasn't done in the right way?
While most commercial tools implement some sort of data protection, data breaches are unfortunately not unheard of. Sweden and Finland have seen a number of high-profile attacks in recent years, including the SportAdmin leak and the Vastaamo data breach, which exposed sensitive data of over 30 000 patients. In 2019, 2.7 million recorded calls to the 1177 healthcare advice line were left on a server with no encryption or password protection, exposing deeply sensitive health information to anyone who found it. The reasons behind each leak are complex, but they share a common thread: the data was stored in a form the provider itself could read. An attacker might get in through a stolen password, system misconfiguration or a software bug — but once the attacker is inside, nothing stands between them and your data. Essentially, if the provider can read your data, so can a hacker the moment they reach its systems.
Doesn't GDPR protect my data?
GDPR imposes strong requirements on who can access your data, for how long, and what type of data. It requires that a company has reasonable justification to keep your data, and that only people with a legitimate interest can access it. It does not strictly require encryption, but it requires that your data is handled with care, and it actually names encryption as one example of a sensible precaution. But GDPR is mostly about process and accountability; it is not a technical guarantee. If a bug or an attack exposes your data, that is a personal data breach, and the company is obliged to report it and, if the risk is high, to warn everyone affected. Whether they are fined depends on whether they took appropriate precautions, but the data is out either way. In other words, GDPR can punish a leak after the fact; it cannot un-leak your data.
Why is Dagning's encryption stronger than most other solutions?
The principle behind the way Dagning stores data is zero-knowledge, client-side encryption. A special key is used to encrypt the data on your device (a phone or computer) before it is sent to a server. When the data reaches the recipient, they need that same key to read it. The key itself is never sent to our servers; it stays only in the memory of your device.
Going back to the Caesar Cipher: if you and a fellow board member agree on a specific number of letters to shift by, you can easily read each other's messages. Anyone intercepting them would have to figure out how many letters to shift. When using Dagning, even if a hacker got hold of the data on our servers, they couldn't read it without your key.
This is not standard practice. Most services encrypt data in transit (while it travels from your device to the server) and at rest (while it sits in their database), but they keep the keys. If a hacker gets into their database and obtains their key, they can read everything. With Dagning, we never even see your key, let alone store it. It always stays on your device, private.
What happens during BankID signing?
To be able to sign a document, our signing provider Idura needs to receive it unencrypted. At this moment, this document leaves your device in a readable format, but all communication between your device and Idura still happens through secure channels (HTTPS). During this window, the document is protected by Idura's own security measures rather than by your encryption key. This is why, as soon as signing is complete, Idura deletes the document from their servers and sends it back to Dagning where it is stored encrypted like everything else.
What happens if the passphrase is lost?
One thing to keep in mind with this kind of encryption is that nobody can restore your data if you lose the passphrase. Dagning stores the passphrase on each BRF board member's device, so the risk that everyone loses it is low, but make sure that when the board members rotate after årsstämma, the passphrase is passed on to the new members. Write it down and store it in a secure place, together with other sensitive documents of the BRF.
Why do I need such a long passphrase?
The reason is that, with modern technology, a Caesar Cipher provides no real protection. A computer can work out the original message in seconds. After all, it's just a simple shift of a few letters. That's why we can't rely on a single small number; we need something far harder to guess.
The app generates a random four-word passphrase from a list of Swedish or English words. This passphrase is run through a modern algorithm (Argon2id) to create a strong secret key, which encrypts all the data you store in Dagning. Four ordinary words may not look like much, but because they are randomly generated by the app (avoiding common phrases) and combined with the modern key generation algorithm, they provide an encryption key so strong that even modern computers cannot crack it in any reasonable time.
How do I share the passphrase with others?
Because the passphrase is the literal key to your data, you need to keep it safe. Don't share it over SMS or other unencrypted channels. The best way to share it is verbally, in person or over the phone. The important thing is that it is never written down somewhere a hacker could easily reach it. If you have a physical safe or other secure place where you keep your sensitive documents, you can write the passphrase on a piece of paper and store it there. The key is never sent to any server - it always stays on your device, protected by Android's or iOS's secure storage.
In order to look up the passphrase, any member of the board who is logged into Dagning can go to More → Settings and scroll down to the button that says "Show your encryption passphrase", confirming with Face ID or however else you unlock your phone. One important thing to understand: this only works on a device where the user is already signed in and the key is stored. Because the key never leaves your device, nobody - not even us - can recover it for you. If every member forgets or loses the passphrase, your data cannot be recovered. That is the price of true privacy.