Is Slack end-to-end encrypted? No. Here is how to send messages your admin can't read

What Slack can and cannot see

Slack's security page says that "customer data is encrypted at rest and in transit by default", and its security practices page describes "the latest recommended secure cypher suites and protocols to encrypt all traffic in transit". Neither page mentions end-to-end encryption, because Slack does not offer it. The keys stay with Slack. That is what lets Slack search your history and run its own features, and it means the protection stops at Slack's door: encryption in transit and at rest guards against someone tapping the wire or stealing a disk, not against the service itself or anyone it lets in.

Who does it let in? Slack's privacy policy says the organisation that signed the customer agreement, usually your employer, "controls its instance of the Services": "Slack is a processor of Customer Data and the Customer is the controller". Slack's export guide then sets out what that controller can take out. On Free and Pro plans, owners can export public channels; for private channels and direct messages they must apply to Slack and show "valid legal process, or consent of members, or a requirement or right under applicable laws". On Business+, a workspace owner can apply for a self-serve tool that exports "all channels and conversations, including private channels and direct messages". On Enterprise, org owners can export everything, including "all conversations that a single user is part of". Slack's only condition is that the right employment agreements and policies are in place and the law allows it.

Then there is retention. On paid plans, Slack's help centre says, "data is kept for the lifetime of your workspace by default". Workspace owners set retention for public channels, private channels and direct messages, and can keep "all versions of an edited or deleted message". Deleting a message removes it from your screen; whether it is gone is decided by a setting you may not be able to see.

And Slack's own staff? The security practices page says employees "are prohibited from using these permissions to view Customer Data unless it is necessary to do so", and that access is logged. That is a policy and a log, not a technical impossibility: the honest position for a service that holds the keys.

Why this matters to ordinary people

Most workspaces never run an export, and no manager sits behind your DMs. The point is that the decision is not yours. A direct message to a colleague about a health problem, a salary, a grievance or a union meeting sits in a system your employer controls and Slack can read. It stays as long as the workspace exists unless someone changes a setting, and can be pulled out years later in a dispute, an investigation or a legal request.

It applies in reverse too. A freelancer or contractor in a client's workspace is subject to the client's retention and export rights. A lawyer talking to a client in the client's Slack, or a journalist talking to a source who only has Slack, is writing into someone else's archive.

How HushHush helps

HushHush encrypts the text on your phone before it goes near Slack. Slack carries only ciphertext: a block of characters it can store, search, export and retain, but cannot read. The other person copies it out of Slack and decrypts it in their HushHush. Both people need the app and pair once, in person, by scanning each other's QR code. No account, no sign-up, no server of ours; the keys live on the two phones and nowhere else.

What HushHush does not do. It does not hide who you talk to, when, or how often: Slack still sees that you messaged that person at that time, how long it was, and the ciphertext itself, and an export still contains all of it. Both people need HushHush, so it will not help with a colleague who has not paired. It protects the text you type, not Slack's huddles or calls. And it is not a way around workplace rules about what work channels are for.

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