{
			queryParams: map[string]string{
				"Expires":        "60",
				"Signature":      "badsignature",
				"AWSAccessKeyId": accessKey,
			},
			expected: ErrExpiredPresignRequest,
		},
		// (4) Should error when the signature does not match.
		{
			queryParams: map[string]string{
				"Expires":        fmt.Sprintf("%d", now.Unix()+60),
				"Signature":      "badsignature",
				"AWSAccessKeyId": accessKey,
			},

	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

	}
	// List of readers used.
	readers := []io.Reader{
		// Test - 1
		bytes.NewReader([]byte("1000;chunk-signature=111123333333333333334444211\r\n")),
		// Test - 2
		bytes.NewReader([]byte("1000;")),
		// Test - 3
		bytes.NewReader(fmt.Appendf(nil, "%4097d", 1)),
		// Test - 4
		bytes.NewReader([]byte("1000;chunk-signature=111123333333333333334444211\r\n")),
	}
	testCases := []testCase{
		// Test - 1 - small bufio reader.
		{

    }

    /**
     * Gets the signature or authentication tag for the encrypted message
     *
     * @return the signature/authentication tag
     */
    public byte[] getSignature() {
        return this.signature;
    }

    /**
     * Sets the signature or authentication tag for the encrypted message
     *
     * @param signature
     *            the signature/authentication tag to set
     */

            // Zero signature field for calculation
            for (int i = 0; i < SIGNATURE_LENGTH; i++) {
                data[SIGNATURE_OFFSET + i] = 0;
            }

            mac.update(data, 0, data.length);
            byte[] signature = mac.doFinal();

            // Place signature in data
            System.arraycopy(signature, 0, data, SIGNATURE_OFFSET, SIGNATURE_LENGTH);

					VersionID: [16]byte{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
					ModTime:   baseTime.Add(30 * time.Minute).UnixNano(),
					Signature: [4]byte{1, 1, 1, 1},
					Type:      ObjectType,
					Flags:     0,
				}},
			},
		},
		// Mismatches Modtime+Signature and older...
		1: {
			versions: []xlMetaV2ShallowVersion{
				{header: xlMetaV2VersionHeader{

            throw new IllegalArgumentException("Signature field exceeds data buffer size");
        }

        // Use fine-grained locking for better concurrency
        this.signingLock.lock();
        try {
            if (this.closed) {
                throw new IllegalStateException("SigningDigest is closed");
            }

            // zero out signature field

	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.

	if err != nil {
		t.Fatal(err)
	}
	v0 := xl.versions[0]

	// Saved with signature 0xfe, 0x54, 0xbc, 0x2f
	// Signature must be converted after load.
	wantSig := [4]byte{0x1e, 0x5f, 0xba, 0x4a}
	if v0.header.Signature != wantSig {
		t.Errorf("Wrong signature, want %#v, got %#v", wantSig, v0.header.Signature)
	}
	v, err := xl.getIdx(0)
	if err != nil {
		t.Fatal(err)
	}

	}
}

// postPresignSignatureV4 - presigned signature for PostPolicy requests.
func postPresignSignatureV4(policyBase64 string, t time.Time, secretAccessKey, location string) string {
	// Get signining key.
	signingkey := getSigningKey(secretAccessKey, t, location, "s3")
	// Calculate signature.
	signature := getSignature(signingkey, policyBase64)
	return signature
}