How Terraform provider make `AWS4-HMAC-SHA256` signature

Terraform Providers AWS
1

I want to confirm my secret_key is right.

So I am using ‘aws’ provider to make JWT token.
This JWT token will be sent to golang based server.

I checked

terraform-provider-aws/internal/service/iam/access_key.go

And there, as I think,

func hmacSignature(key []byte, value []byte) ([]byte, error) {
	h := hmac.New(sha256.New, key)
	if _, err := h.Write(value); err != nil {
		return []byte(""), err
	}
	return h.Sum(nil), nil
}

func SessmTPPasswordFromSecretKeySigV4(key *string, region string) (string, error) {
	if key == nil {
		return "", nil
	}
	const version = byte(0x04)
	date := []byte("11111111")
	service := []byte("ses")
	terminal := []byte("aws4_request")
	message := []byte("SendRawEmail")

	rawSig, err := hmacSignature([]byte("AWS4"+*key), date)
	if err != nil {
		return "", err
	}

	if rawSig, err = hmacSignature(rawSig, []byte(region)); err != nil {
		return "", err
	}
	if rawSig, err = hmacSignature(rawSig, service); err != nil {
		return "", err
	}
	if rawSig, err = hmacSignature(rawSig, terminal); err != nil {
		return "", err
	}
	if rawSig, err = hmacSignature(rawSig, message); err != nil {
		return "", err
	}

	versionedSig := make([]byte, 0, len(rawSig)+1)
	versionedSig = append(versionedSig, version)
	versionedSig = append(versionedSig, rawSig...)
	return base64.StdEncoding.EncodeToString(versionedSig), nil
}

There functions will be used to make AWS4-HMAC-SHA256 signature of that.

And my question is.

  1. Is this code write that terraform ‘aws’ provider make AWS4-HMAC-SHA256 signature?
  2. In here, date, service, terminal, message are hard-coded… Are they used as it is??

Thank you!!