Manage storage account keys with Key Vault and Azure PowerShell (legacy)
Key Vault Managed Storage Account Keys (legacy) is supported as-is with no more updates planned. Only Account SAS are supported with SAS definitions signed storage service version no later than 2018-03-28.
We recommend using Azure Storage integration with Azure Active Directory (Azure AD), Microsoft's cloud-based identity and access management service. Azure AD integration is available for Azure blobs and queues, and provides OAuth2 token-based access to Azure Storage (just like Azure Key Vault). Azure AD allows you to authenticate your client application by using an application or user identity, instead of storage account credentials. You can use an Azure AD managed identity when you run on Azure. Managed identities remove the need for client authentication and storing credentials in or with your application. Use below solution only when Azure AD authentication is not possible.
An Azure storage account uses credentials comprising an account name and a key. The key is autogenerated and serves as a password, rather than an as a cryptographic key. Key Vault manages storage account keys by periodically regenerating them in storage account and provides shared access signature tokens for delegated access to resources in your storage account.
You can use the Key Vault managed storage account key feature to list (sync) keys with an Azure storage account, and regenerate (rotate) the keys periodically. You can manage keys for both storage accounts and Classic storage accounts.
When you use the managed storage account key feature, consider the following points:
- Key values are never returned in response to a caller.
- Only Key Vault should manage your storage account keys. Don't manage the keys yourself and avoid interfering with Key Vault processes.
- Only a single Key Vault object should manage storage account keys. Don't allow key management from multiple objects.
- Regenerate keys by using Key Vault only. Don't manually regenerate your storage account keys.
Regenerating key directly in storage account breaks managed storage account setup and can invalidate SAS tokens in use and cause an outage.
We recommend that you use the Azure Az PowerShell module to interact with Azure. See Install Azure PowerShell to get started. To learn how to migrate to the Az PowerShell module, see Migrate Azure PowerShell from AzureRM to Az.
Service principal application ID
An Azure AD tenant provides each registered application with a service principal. The service principal serves as the application ID, which is used during authorization setup for access to other Azure resources via Azure RBAC.
Key Vault is a Microsoft application that's pre-registered in all Azure AD tenants. Key Vault is registered under the same Application ID in each Azure cloud.
|Azure AD||Azure Government||
|Azure AD||Azure public||
To complete this guide, you must first do the following:
- Install the Azure PowerShell module.
- Create a key vault
- Create an Azure storage account. The storage account name must use only lowercase letters and numbers. The length of the name must be between 3 and 24 characters.
Manage storage account keys
Connect to your Azure account
Authenticate your PowerShell session using the Connect-AzAccount cmdlet.
Set-AzContext -SubscriptionId <subscriptionId>
First, set the variables to be used by the PowerShell cmdlets in the following steps. Be sure to update the "YourResourceGroupName", "YourStorageAccountName", and "YourKeyVaultName" placeholders, and set $keyVaultSpAppId to
cfa8b339-82a2-471a-a3c9-0fc0be7a4093 (as specified in Service principal application ID, above).
$resourceGroupName = <YourResourceGroupName> $storageAccountName = <YourStorageAccountName> $keyVaultName = <YourKeyVaultName> $keyVaultSpAppId = "cfa8b339-82a2-471a-a3c9-0fc0be7a4093" $storageAccountKey = "key1" #(key1 or key2 are allowed) # Get your User Id $userId = (Get-AzContext).Account.Id # Get a reference to your Azure storage account $storageAccount = Get-AzStorageAccount -ResourceGroupName $resourceGroupName -StorageAccountName $storageAccountName
For Classic Storage Account use "primary" and "secondary" for $storageAccountKey
Use 'Get-AzResource -Name "ClassicStorageAccountName" -ResourceGroupName $resourceGroupName' instead of'Get-AzStorageAccount' for Classic Storage Account
Give Key Vault access to your storage account
Before Key Vault can access and manage your storage account keys, you must authorize its access your storage account. The Key Vault application requires permissions to list and regenerate keys for your storage account. These permissions are enabled through the Azure built-in role Storage Account Key Operator Service Role.
Assign this role to the Key Vault service principal, limiting scope to your storage account, using the Azure PowerShell New-AzRoleAssignment cmdlet.
# Assign Azure role "Storage Account Key Operator Service Role" to Key Vault, limiting the access scope to your storage account. For a classic storage account, use "Classic Storage Account Key Operator Service Role." New-AzRoleAssignment -ApplicationId $keyVaultSpAppId -RoleDefinitionName 'Storage Account Key Operator Service Role' -Scope $storageAccount.Id
Upon successful role assignment, you should see output similar to the following example:
RoleAssignmentId : /subscriptions/03f0blll-ce69-483a-a092-d06ea46dfb8z/resourceGroups/rgContoso/providers/Microsoft.Storage/storageAccounts/sacontoso/providers/Microsoft.Authorization/roleAssignments/189cblll-12fb-406e-8699-4eef8b2b9ecz Scope : /subscriptions/03f0blll-ce69-483a-a092-d06ea46dfb8z/resourceGroups/rgContoso/providers/Microsoft.Storage/storageAccounts/sacontoso DisplayName : Azure Key Vault SignInName : RoleDefinitionName : storage account Key Operator Service Role RoleDefinitionId : 81a9662b-bebf-436f-a333-f67b29880f12 ObjectId : 93c27d83-f79b-4cb2-8dd4-4aa716542e74 ObjectType : ServicePrincipal CanDelegate : False
If Key Vault has already been added to the role on your storage account, you'll receive a "The role assignment already exists." error. You can also verify the role assignment, using the storage account "Access control (IAM)" page in the Azure portal.
Give your user account permission to managed storage accounts
Use the Azure PowerShell Set-AzKeyVaultAccessPolicy cmdlet to update the Key Vault access policy and grant storage account permissions to your user account.
# Give your user principal access to all storage account permissions, on your Key Vault instance Set-AzKeyVaultAccessPolicy -VaultName $keyVaultName -UserPrincipalName $userId -PermissionsToStorage get, list, delete, set, update, regeneratekey, getsas, listsas, deletesas, setsas, recover, backup, restore, purge
Note that permissions for storage accounts aren't available on the storage account "Access policies" page in the Azure portal.
Add a managed storage account to your Key Vault instance
Use the Azure PowerShell Add-AzKeyVaultManagedStorageAccount cmdlet to create a managed storage account in your Key Vault instance. The
-DisableAutoRegenerateKey switch specifies NOT to regenerate the storage account keys.
# Add your storage account to your Key Vault's managed storage accounts Add-AzKeyVaultManagedStorageAccount -VaultName $keyVaultName -AccountName $storageAccountName -AccountResourceId $storageAccount.Id -ActiveKeyName $storageAccountKey -DisableAutoRegenerateKey
Upon successful addition of the storage account with no key regeneration, you should see output similar to the following example:
Id : https://kvcontoso.vault.azure.net:443/storage/sacontoso Vault Name : kvcontoso AccountName : sacontoso Account Resource Id : /subscriptions/03f0blll-ce69-483a-a092-d06ea46dfb8z/resourceGroups/rgContoso/providers/Microsoft.Storage/storageAccounts/sacontoso Active Key Name : key1 Auto Regenerate Key : False Regeneration Period : 90.00:00:00 Enabled : True Created : 11/19/2018 11:54:47 PM Updated : 11/19/2018 11:54:47 PM Tags :
Enable key regeneration
If you want Key Vault to regenerate your storage account keys periodically, you can use the Azure PowerShell Add-AzKeyVaultManagedStorageAccount cmdlet to set a regeneration period. In this example, we set a regeneration period of thirty days. When it is time to rotate, Key Vault regenerates the key that is not active, and then sets the newly created key as active. Only one of the keys are used to issue SAS tokens at any one time. This is the active key.
$regenPeriod = [System.Timespan]::FromDays(30) Add-AzKeyVaultManagedStorageAccount -VaultName $keyVaultName -AccountName $storageAccountName -AccountResourceId $storageAccount.Id -ActiveKeyName $storageAccountKey -RegenerationPeriod $regenPeriod
Upon successful addition of the storage account with key regeneration, you should see output similar to the following example:
Id : https://kvcontoso.vault.azure.net:443/storage/sacontoso Vault Name : kvcontoso AccountName : sacontoso Account Resource Id : /subscriptions/03f0blll-ce69-483a-a092-d06ea46dfb8z/resourceGroups/rgContoso/providers/Microsoft.Storage/storageAccounts/sacontoso Active Key Name : key1 Auto Regenerate Key : True Regeneration Period : 30.00:00:00 Enabled : True Created : 11/19/2018 11:54:47 PM Updated : 11/19/2018 11:54:47 PM Tags :
Shared access signature tokens
You can also ask Key Vault to generate shared access signature tokens. A shared access signature provides delegated access to resources in your storage account. You can grant clients access to resources in your storage account without sharing your account keys. A shared access signature provides you with a secure way to share your storage resources without compromising your account keys.
The commands in this section complete the following actions:
- Set an account shared access signature definition.
- Set a Key Vault managed storage shared access signature definition in the vault. The definition has the template URI of the shared access signature token that was created. The definition has the shared access signature type
accountand is valid for N days.
- Verify that the shared access signature was saved in your key vault as a secret.
First, set the variables to be used by the PowerShell cmdlets in the following steps. Be sure to update the <YourStorageAccountName> and <YourKeyVaultName> placeholders.
We will also use the Azure PowerShell New-AzStorageContext cmdlets to get the context of your Azure storage account.
$storageAccountName = <YourStorageAccountName> $keyVaultName = <YourKeyVaultName> $storageContext = New-AzStorageContext -StorageAccountName $storageAccountName -Protocol Https -StorageAccountKey Key1 #(or "Primary" for Classic Storage Account)
Define a shared access signature definition template
Key Vault uses SAS definition template to generate tokens for client applications.
SAS definition template example:
Account SAS parameters required in SAS definition template for Key Vault
|SAS Query Parameter||Description|
||Required. Specifies the signed storage service version to use to authorize requests made with this account SAS. Must be set to version 2015-04-05 or later. Key Vault supports versions no later than 2018-03-28|
||Required. Specifies the signed services accessible with the account SAS. Possible values include:
- Blob (
- Queue (
- Table (
- File (
You can combine values to provide access to more than one service. For example,
||Required. Specifies the signed resource types that are accessible with the account SAS.
- Service (
- Container (
- Object (
You can combine values to provide access to more than one resource type. For example,
||Required. Specifies the signed permissions for the account SAS. Permissions are only valid if they match the specified signed resource type; otherwise they are ignored.
- Read (
- Write (
- Delete (
- Permanent Delete (
- List (
- Add (
- Create (
- Update (
- Process (
- Tag (
- Filter (
- Set Immutability Policy (
||Optional. Specifies the protocol permitted for a request made with the account SAS. Possible values are both HTTPS and HTTP (
Note that HTTP only is not a permitted value.
For more information about account SAS, see: Create an account SAS
Key Vault ignores lifetime parameters like 'Signed Expiry', 'Signed Start' and parameters introduced after 2018-03-28 version
Set shared access signature definition in Key Vault
Use the the Azure PowerShell Set-AzKeyVaultManagedStorageSasDefinition cmdlet to create a shared access signature definition. You can provide the name of your choice to the
Set-AzKeyVaultManagedStorageSasDefinition -AccountName $storageAccountName -VaultName $keyVaultName -Name <YourSASDefinitionName> -TemplateUri $sasTemplate -SasType 'account' -ValidityPeriod ([System.Timespan]::FromDays(1))
Verify the shared access signature definition
You can verify that the shared access signature definition has been stored in your key vault using the Azure PowerShell Get-AzKeyVaultSecret cmdlet.
First, find the shared access signature definition in your key vault.
Get-AzKeyVaultSecret -VaultName <YourKeyVaultName>
The secret corresponding to your SAS definition will have these properties:
Vault Name : <YourKeyVaultName> Name : <SecretName> ... Content Type : application/vnd.ms-sastoken-storage Tags :
You can now use the Get-AzKeyVaultSecret cmdlet with the
Name parameters to view the contents of that secret.
$secretValueText = Get-AzKeyVaultSecret -VaultName <YourKeyVaultName> -Name <SecretName> -AsPlainText Write-Output $secretValueText
The output of this command will show your SAS definition string.
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