You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: hash.go
    path of file: ./repos/malice/vendor/github.com/docker/libtrust
    
    the code of the file until where you have to start completion: package libtrust

import (
	"crypto"
	_ "crypto/sha256" // Registrer SHA224 
    
func rsaSignatureAlgorithmByName(alg string) (*signatureAlgorithm, error) {
	switch {
	case alg == "RS256":
		return rs256, nil
	case alg == "RS384":
		return rs384, nil
	case alg == "RS512":
		return rs512, nil
	default:
		return nil, fmt.Errorf("RSA Digital Signature Algorithm %q not supported", alg)
	}
}