# UpdateAlias


Associates an existing Amazon KMS alias with a different KMS key. Each alias is associated with only one KMS key at a time, although a KMS key can have multiple aliases. The alias and the KMS key must be in the same Amazon Web Services account and Region.

**Note**  
Adding, deleting, or updating an alias can allow or deny permission to the KMS key. For details, see [ABAC for Amazon KMS](https://docs.amazonaws.cn/kms/latest/developerguide/abac.html) in the * Amazon Key Management Service Developer Guide*.

The current and new KMS key must be the same type (both symmetric or both asymmetric or both HMAC), and they must have the same key usage. This restriction prevents errors in code that uses aliases. If you must assign an alias to a different type of KMS key, use [DeleteAlias](API_DeleteAlias.md) to delete the old alias and [CreateAlias](API_CreateAlias.md) to create a new alias.

You cannot use `UpdateAlias` to change an alias name. To change an alias name, use [DeleteAlias](API_DeleteAlias.md) to delete the old alias and [CreateAlias](API_CreateAlias.md) to create a new alias.

Because an alias is not a property of a KMS key, you can create, update, and delete the aliases of a KMS key without affecting the KMS key. Also, aliases do not appear in the response from the [DescribeKey](API_DescribeKey.md) operation. To get the aliases of all KMS keys in the account, use the [ListAliases](API_ListAliases.md) operation. 

The KMS key that you use for this operation must be in a compatible key state. For details, see [Key states of Amazon KMS keys](https://docs.amazonaws.cn/kms/latest/developerguide/key-state.html) in the * Amazon Key Management Service Developer Guide*.

 **Cross-account use**: No. You cannot perform this operation on a KMS key in a different Amazon Web Services account. 

 **Required permissions** 
+  [kms:UpdateAlias](https://docs.amazonaws.cn/kms/latest/developerguide/kms-api-permissions-reference.html) on the alias (IAM policy).
+  [kms:UpdateAlias](https://docs.amazonaws.cn/kms/latest/developerguide/kms-api-permissions-reference.html) on the current KMS key (key policy).
+  [kms:UpdateAlias](https://docs.amazonaws.cn/kms/latest/developerguide/kms-api-permissions-reference.html) on the new KMS key (key policy).

For details, see [Controlling access to aliases](https://docs.amazonaws.cn/kms/latest/developerguide/kms-alias.html#alias-access) in the * Amazon Key Management Service Developer Guide*.

 **Related operations:** 
+  [CreateAlias](API_CreateAlias.md) 
+  [DeleteAlias](API_DeleteAlias.md) 
+  [ListAliases](API_ListAliases.md) 

 **Eventual consistency**: The Amazon KMS API follows an eventual consistency model. For more information, see [Amazon KMS eventual consistency](https://docs.amazonaws.cn/kms/latest/developerguide/accessing-kms.html#programming-eventual-consistency).

## Request Syntax


```
{
   "AliasName": "string",
   "TargetKeyId": "string"
}
```

## Request Parameters


For information about the parameters that are common to all actions, see [Common Parameters](CommonParameters.md).

The request accepts the following data in JSON format.

**Note**  
In the following list, the required parameters are described first.

 ** [AliasName](#API_UpdateAlias_RequestSyntax) **   <a name="KMS-UpdateAlias-request-AliasName"></a>
Identifies the alias that is changing its KMS key. This value must begin with `alias/` followed by the alias name, such as `alias/ExampleAlias`. You cannot use `UpdateAlias` to change the alias name.  
Do not include confidential or sensitive information in this field. This field may be displayed in plaintext in CloudTrail logs and other output.
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 256.  
Pattern: `^alias/[a-zA-Z0-9/_-]+$`   
Required: Yes

 ** [TargetKeyId](#API_UpdateAlias_RequestSyntax) **   <a name="KMS-UpdateAlias-request-TargetKeyId"></a>
Identifies the [customer managed key](https://docs.amazonaws.cn/kms/latest/developerguide/concepts.html#customer-mgn-key) to associate with the alias. You don't have permission to associate an alias with an [Amazon managed key](https://docs.amazonaws.cn/kms/latest/developerguide/concepts.html#aws-managed-key).  
The KMS key must be in the same Amazon Web Services account and Region as the alias. Also, the new target KMS key must be the same type as the current target KMS key (both symmetric or both asymmetric or both HMAC) and they must have the same key usage.   
Specify the key ID or key ARN of the KMS key.  
For example:  
+ Key ID: `1234abcd-12ab-34cd-56ef-1234567890ab` 
+ Key ARN: `arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab` 
To get the key ID and key ARN for a KMS key, use [ListKeys](API_ListKeys.md) or [DescribeKey](API_DescribeKey.md).  
To verify that the alias is mapped to the correct KMS key, use [ListAliases](API_ListAliases.md).  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 2048.  
Required: Yes

## Response Elements


If the action is successful, the service sends back an HTTP 200 response with an empty HTTP body.

## Errors


For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).

 ** DependencyTimeoutException **   
The system timed out while trying to fulfill the request. You can retry the request.  
HTTP Status Code: 500

 ** KMSInternalException **   
The request was rejected because an internal exception occurred. The request can be retried.  
HTTP Status Code: 500

 ** KMSInvalidStateException **   
The request was rejected because the state of the specified resource is not valid for this request.  
This exceptions means one of the following:  
+ The key state of the KMS key is not compatible with the operation. 

  To find the key state, use the [DescribeKey](API_DescribeKey.md) operation. For more information about which key states are compatible with each Amazon KMS operation, see [Key states of Amazon KMS keys](https://docs.amazonaws.cn/kms/latest/developerguide/key-state.html) in the * * Amazon Key Management Service Developer Guide* *.
+ For cryptographic operations on KMS keys in custom key stores, this exception represents a general failure with many possible causes. To identify the cause, see the error message that accompanies the exception.
HTTP Status Code: 400

 ** LimitExceededException **   
The request was rejected because a length constraint or quota was exceeded. For more information, see [Quotas](https://docs.amazonaws.cn/kms/latest/developerguide/limits.html) in the * Amazon Key Management Service Developer Guide*.  
HTTP Status Code: 400

 ** NotFoundException **   
The request was rejected because the specified entity or resource could not be found.  
HTTP Status Code: 400

## Examples


### Example Request


The following example is formatted for legibility.

```
POST / HTTP/1.1
Host: kms.us-east-2.amazonaws.com
Content-Length: 90
X-Amz-Target: TrentService.UpdateAlias
X-Amz-Date: 20161212T193252Z
Content-Type: application/x-amz-json-1.1
Authorization: AWS4-HMAC-SHA256\
 Credential=AKIAI44QH8DHBEXAMPLE/20161212/us-east-2/kms/aws4_request,\
 SignedHeaders=content-type;host;x-amz-date;x-amz-target,\
 Signature=3d6375048a5917aff38f25b92e66bceb16b29562193f7ab7f869b4c53f115c20

{
  "TargetKeyId": "1234abcd-12ab-34cd-56ef-1234567890ab",
  "AliasName": "alias/ExampleAlias"
}
```

### Example Response


This example illustrates one usage of UpdateAlias.

```
HTTP/1.1 200 OK
Server: Server
Date: Mon, 12 Dec 2016 19:32:53 GMT
Content-Type: application/x-amz-json-1.1
Content-Length: 0
Connection: keep-alive
x-amzn-RequestId: c64706c8-c0a1-11e6-b0c0-3343f53dee45
```

## See Also


For more information about using this API in one of the language-specific Amazon SDKs, see the following:
+  [Amazon Command Line Interface V2](https://docs.amazonaws.cn/goto/cli2/kms-2014-11-01/UpdateAlias) 
+  [Amazon SDK for .NET V4](https://docs.amazonaws.cn/goto/DotNetSDKV4/kms-2014-11-01/UpdateAlias) 
+  [Amazon SDK for C\$1\$1](https://docs.amazonaws.cn/goto/SdkForCpp/kms-2014-11-01/UpdateAlias) 
+  [Amazon SDK for Go v2](https://docs.amazonaws.cn/goto/SdkForGoV2/kms-2014-11-01/UpdateAlias) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/kms-2014-11-01/UpdateAlias) 
+  [Amazon SDK for JavaScript V3](https://docs.amazonaws.cn/goto/SdkForJavaScriptV3/kms-2014-11-01/UpdateAlias) 
+  [Amazon SDK for Kotlin](https://docs.amazonaws.cn/goto/SdkForKotlin/kms-2014-11-01/UpdateAlias) 
+  [Amazon SDK for PHP V3](https://docs.amazonaws.cn/goto/SdkForPHPV3/kms-2014-11-01/UpdateAlias) 
+  [Amazon SDK for Python](https://docs.amazonaws.cn/goto/boto3/kms-2014-11-01/UpdateAlias) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/kms-2014-11-01/UpdateAlias)