if len(signedHdrFields) != 2 {
		return nil, ErrMissingFields
	}
	if signedHdrFields[0] != "SignedHeaders" {
		return nil, ErrMissingSignHeadersTag
	}
	if signedHdrFields[1] == "" {
		return nil, ErrMissingFields
	}
	signedHeaders := strings.Split(signedHdrFields[1], ";")
	return signedHeaders, ErrNone
}

// signValues data type represents structured form of AWS Signature V4 header.

			// validating signed headers.
			if strings.Join(testCase.expectedPreSignValues.SignedHeaders, ",") != strings.Join(parsedPreSign.SignedHeaders, ",") {
				t.Errorf("Test %d: Expected the result to be \"%v\", but got \"%v\". ", i+1, testCase.expectedPreSignValues.SignedHeaders, parsedPreSign.SignedHeaders)
			}
			// validating signature field.

	if err != nil {
		t.Fatal(err)
	}
	req.RequestURI = "/?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=USWUXHGYZQYFYFFIT3RE%2F20170529%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20170529T190139Z&X-Amz-Expires=600&X-Amz-Signature=19b58080999df54b446fc97304eb8dda60d3df1812ae97f3e8783351bfd9781d&X-Amz-SignedHeaders=host&prefix=Hello%2AWorld%2A"

	//  <HTTPMethod>\n
	//  <CanonicalURI>\n
	//  <CanonicalQueryString>\n
	//  <CanonicalHeaders>\n
	//  <SignedHeaders>\n
	//  <HashedPayload>
	//
	canonicalRequest := strings.Join([]string{
		req.Method,
		canonicalURI,
		req.URL.RawQuery,
		canonicalHeaders,
		signedHeaders,
		hashedPayload,
	}, "\n")

	// Get scope.
	scope := strings.Join([]string{
		currTime.Format(yyyymmdd),

		return cred, "", "", time.Time{}, ErrContentSHA256Mismatch
	}

	// Extract all the signed headers along with its values.
	extractedSignedHeaders, errCode := extractSignedHeaders(signV4Values.SignedHeaders, r)
	if errCode != ErrNone {
		return cred, "", "", time.Time{}, errCode
	}

	cred, _, errCode = checkKeyValid(r, signV4Values.Credential.accessKey)
	if errCode != ErrNone {

	req = signer.StreamingUnsignedV4(req, "", 8, now)

	maliciousHeaders := http.Header{
		"Authorization":                []string{fmt.Sprintf("AWS4-HMAC-SHA256 Credential=%s/%s/us-east-1/s3/aws4_request, SignedHeaders=invalidheader, Signature=deadbeefdeadbeefdeadbeeddeadbeeddeadbeefdeadbeefdeadbeefdeadbeef", s.accessKey, now.Format(yyyymmdd))},
		"User-Agent":                   []string{"A malicious request"},