if err != nil {
			return 0, errObjectTampered
		}
		size += int64(partSize)
	}
	return size, nil
}

// DecryptETag decrypts the ETag that is part of given object
// with the given object encryption key.
//
// However, DecryptETag does not try to decrypt the ETag if
// it consists of a 128 bit hex value (32 hex chars) and exactly
// one '-' followed by a 32-bit number.

		ETag:       "",
		ShouldFail: true, // ETag contains multiple: -
	},
}

func TestDecryptETag(t *testing.T) {
	for i, test := range decryptETagTests {
		etag, err := DecryptETag(test.ObjectKey, test.ObjectInfo)
		if err != nil && !test.ShouldFail {
			t.Fatalf("Test %d: should succeed but failed: %v", i, err)
		}
		if err == nil && test.ShouldFail {

			}
			if len(etag) >= 32 && strings.Count(etag, "-") != 1 {
				etag = etag[len(etag)-32:]
			}
		case crypto.S3:
			w.Header().Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionAES)
			etag, _ = DecryptETag(objectEncryptionKey, ObjectInfo{ETag: etag})
		case crypto.SSEC:
			w.Header().Set(xhttp.AmzServerSideEncryptionCustomerAlgorithm, r.Header.Get(xhttp.AmzServerSideEncryptionCustomerAlgorithm))

	if kind, encrypted := crypto.IsEncrypted(objInfo.UserDefined); encrypted {
		switch kind {
		case crypto.S3:
			w.Header().Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionAES)
			objInfo.ETag, _ = DecryptETag(objectEncryptionKey, ObjectInfo{ETag: objInfo.ETag})
		case crypto.S3KMS:
			w.Header().Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionKMS)
			w.Header().Set(xhttp.AmzServerSideEncryptionKmsID, objInfo.KMSKeyID())