/* Get function */
    if (Tcl_GetIndexFromObj(interp, objv[1], instance_fns, "function", 0, &fn) != TCL_OK) {
	return TCL_ERROR;
    }

    /* Allocate storage for result. Size should be data size + block size. */
    resultObj = Tcl_NewObj();
    out_buf = Tcl_SetByteArrayLength(resultObj, data_len+EVP_MAX_BLOCK_LENGTH);
    if (resultObj == NULL || out_buf == NULL) {
    if (resultObj == NULL) {
	Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
	Tcl_DecrRefCount(resultObj);
	return TCL_ERROR;
    }

    /* Do function */
    if (fn) {
	/* Get data or return error if none */
	if (objc == 3) {
	    data = Tcl_GetByteArrayFromObj(objv[2], &data_len);
	} else {
	    Tcl_WrongNumArgs(interp, 1, objv, "update data");
	    return TCL_ERROR;
	}

	/* Allocate output buffer */
	out_buf = Tcl_SetByteArrayLength(resultObj, data_len+EVP_MAX_BLOCK_LENGTH);
	if (data == NULL || out_buf == NULL) {
	    Tcl_DecrRefCount(resultObj);
	    Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
	    return TCL_ERROR;
	}

	/* Update function */
	if (EncryptUpdate(interp, statePtr->type, statePtr->ctx, out_buf, &out_len, data, data_len) == TCL_OK) {
	    out_buf = Tcl_SetByteArrayLength(resultObj, (Tcl_Size) out_len);
	    Tcl_SetObjResult(interp, resultObj);
	} else {
	    Tcl_DecrRefCount(resultObj);
	    return TCL_ERROR;
	}

    } else {
	/* Allocate output buffer */
	out_buf = Tcl_SetByteArrayLength(resultObj, EVP_MAX_BLOCK_LENGTH);
	if (out_buf == NULL) {
	    Tcl_DecrRefCount(resultObj);
	    Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
	    return TCL_ERROR;
	}

	/* Finalize function */
	if (EncryptFinalize(interp, statePtr->type, statePtr->ctx, out_buf, &out_len) == TCL_OK) {
	    out_buf = Tcl_SetByteArrayLength(resultObj, (Tcl_Size) out_len);
	    Tcl_SetObjResult(interp, resultObj);
	} else {
	    Tcl_DecrRefCount(resultObj);
	    return TCL_ERROR;

/*******************************************************************/

/*
 *-------------------------------------------------------------------
 *
 * EncryptFileHandler --
 *
 *	Perform encryption function on a block of data and return result.
 *	Perform encryption function on a block of data, write it to a
 *	file, then return the result.
 *
 * Returns:
 *	TCL_OK or TCL_ERROR
 *
 * Side effects:
 *	Encrypts or decrypts inFile data to outFile and sets result to
 *	size of outFile, or an error message.