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Azure Key Vault soft-delete overview

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Important

If a key vault does not have soft-delete protection enabled, deleting a key deletes it permanently. Customers are strongly encouraged to turn on soft delete enforcement for their vaults via Azure Policy.

Important

When a Key Vault is soft-deleted, services that are integrated with the Key Vault will be deleted. For example: Azure RBAC roles assignments and Event Grid subscriptions. Recovering a soft-deleted Key Vault will not restore these services. They will need to be recreated.

Key Vault's soft-delete feature allows recovery of the deleted vaults and deleted key vault objects (for example, keys, secrets, certificates), known as soft-delete. Specifically, we address the following scenarios: This safeguard offer the following protections:

  • Once a secret, key, certificate, or key vault is deleted, it remains recoverable for a configurable period of 7 to 90 calendar days. If no configuration is specified, the default recovery period is set to 90 days to provide users with sufficient time to notice an accidental secret deletion and respond.
  • Two operations must be made to permanently delete a secret. First a user must delete the object, which puts it into the soft-deleted state. Second, a user must purge the object in the soft-deleted state. These protections reduce the risk of a user accidentally or maliciously deleting a secret or a key vault.
  • To purge a secret, key, certificate in the soft-deleted state, a security principal must be granted "purge" operation permission (with the Key Vault built-in role"Key Vault Purge Operator", for example).

Supporting interfaces

The soft-delete feature is available through the REST API, the Azure CLI, Azure PowerShell, and .NET/C# interfaces, as well as ARM templates.

Scenarios

Azure Key Vaults are tracked resources, managed by Azure Resource Manager. Azure Resource Manager also specifies a well-defined behavior for deletion, which requires that a successful DELETE operation must result in that resource not being accessible anymore. The soft-delete feature addresses the recovery of the deleted object, whether the deletion was accidental or intentional.

  1. In the typical scenario, a user inadvertently deletes a key vault or a key vault object; if that key vault or key vault object was recoverable for a predetermined period, the user can undo the deletion and recover their data.

  2. In a different scenario, a rogue user can attempt to delete a key vault or a key vault object, such as a key inside a vault, to cause a business disruption. Separating the deletion of the key vault or key vault object from the actual deletion of the underlying data can be used as a safety measure by, for instance, restricting permissions on data deletion to a different, trusted role. This approach effectively requires quorum for an operation which might otherwise result in an immediate data loss.

Soft-delete behavior

When soft-delete is enabled, resources marked as deleted resources are retained for a specified period (90 days by default). The service further provides a mechanism for recovering the deleted object, essentially undoing the deletion.

When creating a new key vault, soft-delete is on by default. Once soft-delete is enabled on a key vault, it can't be disabled.

The retention policy interval can only be configured during key vault creation and can't be changed afterwards. You can set it anywhere from 7 to 90 days, with 90 days being the default. The same interval applies to both soft-delete and the purge protection retention policy.

You can't reuse the name of a key vault that was soft-deleted, until the retention period expires.

Purge protection

Purge protection is an optional Key Vault behavior and is not enabled by default. Purge protection can only be enabled once soft-delete is enabled. Purge protection is recommended when using keys for encryption to prevent data loss. Most Azure services that integrate with Azure Key Vault, such as Storage, require purge protection to prevent data loss.

When purge protection is on, a vault or an object in the deleted state can't be purged until the retention period passes. Soft-deleted vaults and objects can still be recovered, ensuring that the retention policy is followed.

The default retention period is 90 days, but it's possible to set the retention policy interval to a value from 7 to 90 days through the Azure portal. Once the retention policy interval is set and saved, it can't be changed for that vault.

Purge Protection can be turned on via CLI, PowerShell, or Portal.

Permitted purge

Permanently deleting, purging, a key vault is possible via a POST operation on the proxy resource and requires special privileges. In general, only the subscription owner or a user with the "Key Vault Purge Operator" RBAC role can purge a key vault. The POST operation triggers the immediate and irrecoverable deletion of that vault.

Exceptions are:

  • When the Azure subscription is marked as undeletable. In this case, only the service can then perform the actual deletion, and does so as a scheduled process.
  • When the --enable-purge-protection argument is enabled on the vault itself. In this case, Key Vault will wait for 7 to 90 days from when the original secret object was marked for deletion to permanently delete the object.

For steps, see How to use Key Vault soft-delete with CLI: Purging a key vault or How to use Key Vault soft-delete with PowerShell: Purging a key vault.

Key vault recovery

When a key vault is deleted, the service creates a proxy resource under the subscription, adding sufficient metadata for recovery. The proxy resource is a stored object, available in the same location as the deleted key vault.

Key vault object recovery

When a key vault object, such as a key, is deleted, the service places the object in a deleted state, making it inaccessible to any retrieval operations. While in this state, the key vault object can only be listed, recovered, or forcefully/permanently deleted. To view the objects, use the Azure CLI az keyvault key list-deleted command (as documented in How to use Key Vault soft-delete with CLI), or the Azure PowerShell Get-AzKeyVault -InRemovedState command (as described in How to use Key Vault soft-delete with PowerShell).

At the same time, Key Vault will schedule the deletion of the underlying data corresponding to the deleted key vault or key vault object for execution after a predetermined retention interval. The DNS record corresponding to the vault is also retained during the retention interval.

Soft-delete retention period

Soft-deleted resources are retained for a set period of time, 90 days. During the soft-delete retention interval, the following apply:

  • You can list all of the key vaults and key vault objects in the soft-delete state for your subscription as well as access deletion and recovery information about them.
    • Only users with special permissions can list deleted vaults. We recommend that our users create a custom role with these special permissions for handling deleted vaults.
  • A key vault with the same name can't be created in the same location; correspondingly, a key vault object can't be created in a given vault if that key vault contains an object with the same name and which is in a deleted state.
  • Only a specifically privileged user can restore a key vault or key vault object by issuing a recover command on the corresponding proxy resource.
    • The user, member of the custom role, who has the privilege to create a key vault under the resource group can restore the vault.
  • Only a specifically privileged user can forcibly delete a key vault or key vault object by issuing a delete command on the corresponding proxy resource.

Unless a key vault or key vault object is recovered, at the end of the retention interval the service performs a purge of the soft-deleted key vault or key vault object and its content. Resource deletion can not be rescheduled.

Billing implications

In general, when an object (a key vault or a key or a secret) is in deleted state, there are only two operations possible: 'purge' and 'recover'. All the other operations will fail. Therefore, even though the object exists, no operations can be performed and hence no usage will occur, so no bill. However there are following exceptions:

  • 'purge' and 'recover' actions will count towards normal key vault operations and will be billed.
  • If the object is an HSM-key, the 'HSM Protected key' charge per key version per month charge will apply if a key version has been used in last 30 days. After that, since the object is in deleted state no operations can be performed against it, so no charge will apply.

Next steps

The following three guides offer the primary usage scenarios for using soft-delete.