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Service Bus authentication and authorization

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There are two ways to authenticate and authorize access to Azure Service Bus resources:

  • Microsoft Entra ID
  • Shared Access Signatures (SAS).

This article gives you details on using these two types of security mechanisms.

Microsoft Entra ID

Microsoft Entra integration with Service Bus provides role-based access control (RBAC) to Service Bus resources. You can use Azure RBAC to grant permissions to a security principal, which can be a user, a group, an application service principal, or a managed identity. Microsoft Entra authenticates the security principal and returns an OAuth 2.0 token. This token can be used to authorize a request to access a Service Bus resource (queue, topic, and so on).

For more information about authenticating with Microsoft Entra ID, see the following articles:

Note

Service Bus REST API supports OAuth authentication with Microsoft Entra ID.

Important

Authorizing users or applications using OAuth 2.0 token returned by Microsoft Entra ID provides superior security and ease of use over shared access signatures (SAS). With Microsoft Entra ID, there is no need to store tokens in your code and risk potential security vulnerabilities. We recommend that you use Microsoft Entra ID with your Azure Service Bus applications when possible.

You can disable local or SAS key authentication for a Service Bus namespace and allow only Microsoft Entra authentication. For step-by-step instructions, see Disable local authentication.

Shared access signature

SAS authentication enables you to grant a user access to Service Bus resources, with specific rights. SAS authentication in Service Bus involves the configuration of a cryptographic key with associated rights on a Service Bus resource. Clients can then gain access to that resource by presenting a SAS token, which consists of the resource URI being accessed and an expiry signed with the configured key.

You can configure keys for SAS on a Service Bus namespace. The key applies to all messaging entities within that namespace. You can also configure keys on Service Bus queues and topics. To use SAS, you can configure a shared access authorization rule on a namespace, queue, or topic. This rule consists of the following elements:

  • KeyName: identifies the rule.
  • PrimaryKey: a cryptographic key used to sign/validate SAS tokens.
  • SecondaryKey: a cryptographic key used to sign/validate SAS tokens.
  • Rights: represents the collection of Listen, Send, or Manage rights granted.

Authorization rules configured at the namespace level can grant access to all entities in a namespace for clients with tokens signed using the corresponding key. You can configure up to 12 such authorization rules on a Service Bus namespace, queue, or topic. By default, a shared access authorization rule with all rights is configured for every namespace when it's first provisioned.

To access an entity, the client requires a SAS token generated using a specific shared access authorization rule. The SAS token is generated using the HMAC-SHA256 of a resource string that consists of the resource URI to which access is claimed, and an expiry with a cryptographic key associated with the authorization rule.

SAS authentication support for Service Bus is included in the Azure .NET SDK versions 2.0 and later. SAS includes support for a shared access authorization rule. All APIs that accept a connection string as a parameter include support for SAS connection strings.

Next steps

For more information about authenticating with Microsoft Entra ID, see the following articles:

For more information about authenticating with SAS, see the following articles: