signature := calculateSignatureV2(stringToSign, cred.SecretKey)
	return signature
}

// compareSignatureV2 returns true if and only if both signatures
// are equal. The signatures are expected to be base64 encoded strings
// according to the AWS S3 signature V2 spec.
func compareSignatureV2(sig1, sig2 string) bool {
	// Decode signature string to binary byte-sequence representation is required

			},
			expected: ErrInvalidAccessKeyID,
		},
		// (2) It should fail with a bad signature.
		{
			form: http.Header{
				"X-Amz-Credential": []string{fmt.Sprintf(credentialTemplate, accessKey, now.Format(yyyymmdd), globalMinioDefaultRegion)},
				"X-Amz-Date":       []string{now.Format(iso8601Format)},
				"X-Amz-Signature":  []string{"invalidsignature"},
				"Policy":           []string{"policy"},
			},

		{"X-Amz-Content-Sha256", unsignedPayload, "X-Amz-Credential", "", true},

		// Test case - 4.
		// Enabling PreSigned Signature v4, but X-Amz-Content-Sha256 not set has to be skipped.
		{"", "", "X-Amz-Credential", "", true},

		// Test case - 5.
		// Enabling PreSigned Signature v4, but X-Amz-Content-Sha256 set and its not UNSIGNED-PAYLOAD, we shouldn't skip.

			return n, cr.err
		}
	}

	// Now, we read the signature of the following payload and expect:
	//   chunk-signature=" + <signature-as-hex> + "\r\n"
	//
	// The signature is 64 bytes long (hex-encoded SHA256 hash) and
	// starts with a 16 byte header: len("chunk-signature=") + 64 == 80.
	var signature [80]byte
	_, err = io.ReadFull(cr.reader, signature[:])
	if err == io.EOF {
		err = io.ErrUnexpectedEOF
	}

	if aec != ErrNone {
		return psv, aec
	}

	// Save signature.
	preSignV4Values.Signature, aec = parseSignature("Signature=" + query.Get(xhttp.AmzSignature))
	if aec != ErrNone {
		return psv, aec
	}

	// Return structured form of signature query string.
	return preSignV4Values, ErrNone
}

// Parses signature version '4' header of the following form.
//

	req.URL.RawQuery = query.Encode()

	// Save signature finally.
	req.URL.RawQuery += "&Signature=" + url.QueryEscape(signature)
	return nil
}

// Sign given request using Signature V2.
func signRequestV2(req *http.Request, accessKey, secretKey string) error {
	signer.SignV2(*req, accessKey, secretKey, false)
	return nil
}

// Sign given request using Signature V4.

	tmp := struct {
		VersionID string
		ModTime   time.Time
		Signature string
		Type      uint8
		Flags     uint8
	}{
		VersionID: hex.EncodeToString(z.VersionID[:]),
		ModTime:   time.Unix(0, z.ModTime),
		Signature: hex.EncodeToString(z.Signature[:]),
		Type:      z.Type,
		Flags:     z.Flags,
	}
	return json.Marshal(tmp)

	var buf [dataDescriptorLen]byte
	// The spec says: "Although not originally assigned a
	// signature, the value 0x08074b50 has commonly been adopted
	// as a signature value for the data descriptor record.
	// Implementers should be aware that ZIP files may be
	// encountered with or without this signature marking data
	// descriptors and should account for either case when reading
	// ZIP files to ensure compatibility."

// errMethodNotAllowed means that method is not allowed.
var errMethodNotAllowed = errors.New("Method not allowed")

// errSignatureMismatch means signature did not match.
var errSignatureMismatch = errors.New("Signature does not match")

// When upload object size is greater than 5G in a single PUT/POST operation.
var errDataTooLarge = errors.New("Object size larger than allowed limit")

	}

	if lc != "" {
		args["LocationConstraint"] = []string{lc}
	}

	cloneHeader := r.Header.Clone()
	if v := cloneHeader.Get("x-amz-signature-age"); v != "" {
		args["signatureAge"] = []string{v}
		cloneHeader.Del("x-amz-signature-age")
	}

	if userTags := cloneHeader.Get(xhttp.AmzObjectTagging); userTags != "" {
		tag, _ := tags.ParseObjectTags(userTags)
		if tag != nil {