if credElements[3] != "aws4_request" {
		return ch, ErrInvalidRequestVersion
	}
	cred.scope.request = credElements[3]
	return cred, ErrNone
}

// Parse signature from signature tag.
func parseSignature(signElement string) (string, APIErrorCode) {
	signFields := strings.Split(strings.TrimSpace(signElement), "=")
	if len(signFields) != 2 {
		return "", ErrMissingFields
	}
	if signFields[0] != "Signature" {

		{
			inputSignElement: "Signature=abcd",
			expectedSignStr:  "abcd",
			expectedErrCode:  ErrNone,
		},
	}
	for i, testCase := range testCases {
		actualSignStr, actualErrCode := parseSignature(testCase.inputSignElement)
		if testCase.expectedErrCode != actualErrCode {
			t.Fatalf("Test %d: Expected the APIErrCode to be %d, got %d", i+1, testCase.expectedErrCode, actualErrCode)
		}