Question 1

What is zero-access encryption?

Accepted Answer

Zero-access encryption is a way of protecting your data stored in the cloud so
that only you have access. Proton uses zero-access encryption to store your
personal data, like emails, calendar events, and files, on our servers. Your
data is encrypted using your public key, and only you can decrypt it using your
private key. No one else has access, not even Proton.

With Proton Mail, zero-access encryption only applies to messages stored on
Proton Mail. If the person you wrote an email to doesn’t use Proton Mail, their
email service can likely read it. To send a truly secure message to someone who
isn’t on Proton Mail, you can use a Password-protected Email
[/support/cs/password-protected-emails].

Question 2

Why use end-to-end encryption?

Accepted Answer

End-to-end encryption means that you encrypt your own data on your own device,
and only you and the intended recipient can access it. When you send an
end-to-end encrypted email, no one else can read your message, not even Proton
or the recipient’s email service.

Question 3

What’s the difference between end-to-end encryption and zero-access encryption?

Accepted Answer

At Proton, we use both zero-access encryption and end-to-end encryption
[/cs/security/end-to-end-encryption] to protect your data. To understand the
difference, consider two scenarios:

1. Someone using Gmail sends an email to your Proton Mail account. When it
arrives at Proton Mail, our servers can read that email because Gmail doesn’t
support end-to-end encryption. But after receiving the email, we encrypt it
immediately using your Proton Mail public encryption key. Afterward, only you
can decrypt the encrypted email using your Proton Mail private encryption key.
This is zero-access encryption.

2. Someone on Proton Mail sends an email to your Proton Mail address. The email
is encrypted on the sender’s device using your public encryption key before
being transferred to the Proton Mail server and then to you. In this way, the
message is already encrypted before it reaches our server, and only the sender
and you can decrypt the email. This is end-to-end encryption.

End-to-end encryption is the stronger of these two types of encryption because
Proton never sees the unencrypted message. So for highly sensitive
conversations, we recommend that both parties use Proton Mail or a
Password-protected Email [/support/cs/password-protected-emails]. With
Password-protected Emails, you can send an end-to-end encrypted message to any
email address.

Question 4

What’s encrypted email?

Accepted Answer

Although all major email services use some level of encryption to protect your
emails, the term “encrypted email” is often used to describe an end-to-end
encrypted email service [/cs/mail]. Using end-to-end encrypted email ensures
that only authorized recipients can access the contents of your messages. Not
even the email service itself can read the contents of your emails.

In contrast, email services that don’t use end-to-end encryption retain the
ability to access your emails, hand them over to third parties, and put you at
increased risk in the event of a data breach.

Protect your privacy with zero-access encryption

What is zero-access encryption?

The key to your secure cloud

Protect your privacy with zero-access encryption

Encrypted emails

Encrypted files

Encrypted contacts

Encrypted attachments

Encrypted events

Millions of people worldwide trust Proton’s encryption to stay private

Protect your privacy

Access anywhere

Share securely

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Beat data breaches

Swiss privacy

Open-source security

Stay compliant

Your privacy is our first and only priority

Join the 70 million people and businesses that have entrusted Proton to keep their data private.

You get what you pay for. In the case of big tech, if you pay nothing, you get used. I quit using Gmail and switched to @ProtonMail

My favorite email service

I love my ProtonMail

Thanks Proton for keeping us all safe in the complicated internet universe.

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Zero-access encryption FAQ