return 0, err
		}

		d.partDecRelOffset += int64(n1)
	}
	return len(p), nil
}

// DecryptedSize returns the size of the object after decryption in bytes.
// It returns an error if the object is not encrypted or marked as encrypted
// but has an invalid size.
func (o ObjectInfo) DecryptedSize() (int64, error) {
	if _, ok := crypto.IsEncrypted(o.UserDefined); !ok {

		}
		if size > len(b) {
			size = len(b)
		}

		// Calculate the object real size if encrypted
		if _, ok := crypto.IsEncrypted(gr.ObjInfo.UserDefined); ok {
			objSize, err = gr.ObjInfo.DecryptedSize()
			if err != nil {
				return nil, ObjectInfo{}, err
			}
		} else {
			objSize = gr.ObjInfo.Size
		}

		files, err := zipindex.ReadDir(b[len(b)-size:], objSize, nil)
		if err == nil {

		if sizeStr != "" {
			size, err := strconv.ParseInt(sizeStr, 10, 64)
			if err != nil {
				return -1, errObjectTampered
			}
			return size, nil
		}
		actualSize, err := o.DecryptedSize()
		if err != nil {
			return -1, err
		}
		if (actualSize == 0) && (actualSize != o.Size) {
			return -1, errObjectTampered
		}
		return actualSize, nil
	}
	return o.Size, nil
}

		switch {
		case compressed:
			// ... nothing changes for compressed stream.
			// if actualSize is -1 we have no known way to
			// determine what is the actualSize.
		case encrypted:
			decSize, err := sio.DecryptedSize(uint64(n))
			if err == nil {
				actualSize = int64(decSize)
			}
		default:
			actualSize = n
		}
	}

	partInfo := ObjectPartInfo{
		Number:     partID,
		ETag:       md5hex,

		case compressed:
			// ... nothing changes for compressed stream.
			// if actualSize is -1 we have no known way to
			// determine what is the actualSize.
		case encrypted:
			decSize, err := sio.DecryptedSize(uint64(n))
			if err == nil {
				actualSize = int64(decSize)
			}
		default:
			actualSize = n
		}
	}
	if fi.Checksum == nil {
		// Trailing headers checksums should now be filled.

			targetSize = objInfo.EncryptedSize()
		case !isSourceEncrypted && isTargetEncrypted:
			targetSize = srcInfo.EncryptedSize()
		case isSourceEncrypted && !isTargetEncrypted:
			targetSize, _ = srcInfo.DecryptedSize()
		}

		if isTargetEncrypted {
			var encReader io.Reader
			kind, _ := crypto.IsRequested(r.Header)