# Common Parameters


The following list contains the parameters that all actions use for signing Signature Version 4 requests with a query string. Any action-specific parameters are listed in the topic for that action. For more information about Signature Version 4, see [Signing AWS API requests](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-signing.html) in the *IAM User Guide*.

 **X-Amz-Algorithm**   <a name="CommonParameters-X-Amz-Algorithm"></a>
The hash algorithm that you used to create the request signature.  
Condition: Specify this parameter when you include authentication information in a query string instead of in the HTTP authorization header.  
Type: string  
Valid Values: `AWS4-HMAC-SHA256`   
Required: Conditional

 **X-Amz-Credential**   <a name="CommonParameters-X-Amz-Credential"></a>
The credential scope value, which is a string that includes your access key, the date, the region you are targeting, the service you are requesting, and a termination string ("aws4\$1request"). The value is expressed in the following format: *access\$1key*/*YYYYMMDD*/*region*/*service*/aws4\$1request.  
For more information, see [Create a signed AWS API request](https://docs.aws.amazon.com/IAM/latest/UserGuide/create-signed-request.html) in the *IAM User Guide*.  
Condition: Specify this parameter when you include authentication information in a query string instead of in the HTTP authorization header.  
Type: string  
Required: Conditional

 **X-Amz-Date**   <a name="CommonParameters-X-Amz-Date"></a>
The date that is used to create the signature. The format must be ISO 8601 basic format (YYYYMMDD'T'HHMMSS'Z'). For example, the following date time is a valid X-Amz-Date value: `20120325T120000Z`.  
Condition: X-Amz-Date is optional for all requests; it can be used to override the date used for signing requests. If the Date header is specified in the ISO 8601 basic format, X-Amz-Date is not required. When X-Amz-Date is used, it always overrides the value of the Date header. For more information, see [Elements of an AWS API request signature](https://docs.aws.amazon.com/IAM/latest/UserGuide/signing-elements.html) in the *IAM User Guide*.  
Type: string  
Required: Conditional

 **X-Amz-Security-Token**   <a name="CommonParameters-X-Amz-Security-Token"></a>
The temporary security token that was obtained through a call to AWS Security Token Service (AWS STS). For a list of services that support temporary security credentials from AWS STS, see [AWS services that work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html) in the *IAM User Guide*.  
Condition: If you're using temporary security credentials from AWS STS, you must include the security token.  
Type: string  
Required: Conditional

 **X-Amz-Signature**   <a name="CommonParameters-X-Amz-Signature"></a>
Specifies the hex-encoded signature that was calculated from the string to sign and the derived signing key.  
Condition: Specify this parameter when you include authentication information in a query string instead of in the HTTP authorization header.  
Type: string  
Required: Conditional

 **X-Amz-SignedHeaders**   <a name="CommonParameters-X-Amz-SignedHeaders"></a>
Specifies all the HTTP headers that were included as part of the canonical request. For more information about specifying signed headers, see [Create a signed AWS API request](https://docs.aws.amazon.com/IAM/latest/UserGuide/create-signed-request.html) in the *IAM User Guide*.  
Condition: Specify this parameter when you include authentication information in a query string instead of in the HTTP authorization header.  
Type: string  
Required: Conditional