73 lines
2.9 KiB
Markdown
73 lines
2.9 KiB
Markdown
---
|
|
layout: "docs"
|
|
page_title: "Seal/Unseal"
|
|
sidebar_current: "docs-concepts-seal"
|
|
description: |-
|
|
A Vault must be unsealed before it can access its data. Likewise, it can be sealed to lock it down.
|
|
---
|
|
|
|
# Seal/Unseal
|
|
|
|
When a Vault server is started, it starts in a _sealed_ state. In this
|
|
state, Vault is configured to know where and how to access the physical
|
|
storage, but doesn't know how to decrypt any of it.
|
|
|
|
_Unsealing_ is the process of constructing the master key necessary to
|
|
read the decryption key to decrypt the data, allowing access to the Vault.
|
|
|
|
Prior to unsealing, almost no operations are possible with Vault. For
|
|
example authentication, managing the mount tables, etc. are all not possible.
|
|
The only possible operations are to unseal the Vault and check the status
|
|
of the unseal.
|
|
|
|
## Why?
|
|
|
|
The data stored by Vault is stored encrypted. Vault needs the
|
|
_encryption key_ in order to decrypt the data. The encryption key is
|
|
also stored with the data, but encrypted with another encryption key
|
|
known as the _master key_. The master key isn't stored anywhere.
|
|
|
|
Therefore, to decrypt the data, Vault must decrypt the encryption key
|
|
which requires the master key. Unsealing is the process of reconstructing
|
|
this master key.
|
|
|
|
Instead of distributing this master key as a single key to an operator,
|
|
Vault uses an algorithm known as
|
|
[Shamir's Secret Sharing](https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing)
|
|
to split the key into shards. A certain threshold of shards is required to
|
|
reconstruct the master key.
|
|
|
|
This is the _unseal_ process: the shards are added one at a time (in any
|
|
order) until enough shards are present to reconstruct the key and
|
|
decrypt the data.
|
|
|
|
## Unsealing
|
|
|
|
The unseal process is done by running `vault unseal` or via the API.
|
|
This process is stateful: each key can be entered via multiple mechanisms
|
|
on multiple computers and it will work. This allows each shard of the master
|
|
key to be on a distinct machine for better security.
|
|
|
|
Once a Vault is unsealed, it remains unsealed until one of two things happens:
|
|
|
|
1. It is resealed via the API (see below).
|
|
|
|
2. The server is restarted.
|
|
|
|
-> **Note:** Unsealing makes the process of automating a Vault install
|
|
difficult. Automated tools can easily install, configure, and start Vault,
|
|
but unsealing it is a very manual process. We have plans in the future to
|
|
make it easier. For the time being, the best method is to manually unseal
|
|
multiple Vault servers in [HA mode](/docs/concepts/ha.html). Use a tool such
|
|
as Consul to make sure you only query Vault servers that are unsealed.
|
|
|
|
## Sealing
|
|
|
|
There is also an API to seal the Vault. This will throw away the master
|
|
key and require another unseal process to restore it. Sealing only requires
|
|
a single operator with root privileges.
|
|
|
|
This way, if there is a detected intrusion, the Vault data can be locked
|
|
quickly to try to minimize damages. It can't be accessed again without
|
|
access to the master key shards.
|