Mattermost is an open source group messaging and file transfer service, designed as an alternative to Slack. Their account of their security setup is detailed here. Are the encryption options it offers for the group messaging and file transfer services it offers secure, if it's set up on a secure, internal server?

2 Answers 2


After reading the security details it seems very secure for me. Just to remark some details:

  • Using AES-256 Algorithm: AES (Advanced Encryption Standard) is the Standard and most widely used private key algorithm.
  • RSA with 2048 bit is the most widely used public key algorithm in data transmissions.
  • TLS: is a high security transmission protocol used widely too.

Logging, History, Updates... also makes mattermost so secure.


Messages are encrypted while transmitting between the clients and server, but are not encrypted at rest (in the database). This means anyone with database access can read both channel and private messages.

Not encrypting them, among other things, allows searching.

Encrypting the data storage is left up to the underlying operating system:

Encryption-at-rest is available through hardware and software disk encryption solutions applied to the Mattermost database, which can reside on its own server within your infrastructure.

These can include full disk encryption, but a sysadmin with sufficient access to the server can always get around that.

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