End-to-end encryption

What it means

End-to-end encryption means the sender encrypts the message and only the recipient can decrypt it. The service provider carries the data but cannot read it, because it holds no key.

That differs from ordinary transport encryption, where content is protected in transit but sits readable on the provider’s server. For sensitive data the difference is real - and it is a difference in who you must trust.

End-to-end encryption protects content, not the circumstances of communication. The provider still sees who talks to whom, when, how often and how large the file was. Encrypted content is therefore not the same as anonymous communication or pseudonymisation of data - those answer a different question, namely whether a specific person can be identified from the data.

How it works in practice

In accounting it comes up when payroll runs, copies of ID documents or credentials are sent. The simplest answer is not to e-mail them at all, but to use a shared folder in cloud storage under managed access.

If a sensitive file does go out, it is protected with a password delivered by another channel. A password in the same message cancels the protection.

The same principle works for backups: files are encrypted on the company’s own computer before they leave for the cloud. Data backup set up this way protects payroll and tax records even if someone unauthorised gets into the account at the storage provider, because all they find there is unreadable files.

What to watch out for

Encryption does not protect against the wrong recipient or a compromised device. Nor does it discharge GDPR duties - it is one technical measure, not a substitute for a legal basis and processing records.

With end-to-end encryption only the user holds the key, so a lost key or forgotten password means lost data - the provider cannot recover it. The company needs to decide who manages keys and how they are handed over at offboarding, otherwise it locks itself out of its own records and has nothing to produce when retention rules require it.