}

    /* Make sure to operate on the topmost channel */
    chan = Tcl_GetTopChannel(chan);

    /* Configure channel */
    Tcl_SetChannelOption(interp, chan, "-translation", "binary");
    if (Tcl_GetChannelBufferSize(chan) < EVP_MAX_BLOCK_LENGTH) {
	Tcl_SetChannelBufferSize(chan, EVP_MAX_BLOCK_LENGTH);
    }

    /* Create state data structure */
    if ((statePtr = EncryptStateNew(interp, type)) == NULL) {
	Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
	return TCL_ERROR;
    }
    statePtr->self = chan;

    /* Stack channel */
    statePtr->self = Tcl_StackChannel(interp, &encryptChannelType, (ClientData) statePtr, mode, chan);
    if (statePtr->self == (Tcl_Channel) NULL) {
	EncryptStateFree(statePtr);
	return TCL_ERROR;
    }

    dprintf("Created channel named %s", Tcl_GetChannelName(statePtr->self));

    /* Set result to channel Id */
    Tcl_SetResult(interp, (char *) Tcl_GetChannelName(statePtr->self), TCL_VOLATILE);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Unstack Channel --