new

Signature class should accept HTTPRequest instance and determine every required parameter via this instance

sign_request( $request )

Signature class should return authenticated request based on given parameter. Parameter can be modified.

sign_uri( $request, $expires_at?, $method? )

Signature class should return authenticated uri based on given request.

$expires_at is expiration time in seconds (epoch). Default and maximal allowed value may depend on signature version.

Default request date is current time. Signature class should accept provided "X-Amz-Date" header instead (if signing request) or query parameter (if signing uri)