*-------------------------------------------------------------------
 */
int DigestInitialize(Tcl_Interp *interp, DigestState *statePtr, Tcl_Obj *digestObj,
	Tcl_Obj *cipherObj, Tcl_Obj *keyObj, Tcl_Obj *macObj) {
    int res = 0, type = statePtr->format & 0xFF0;
    const EVP_MD *md = NULL;
    const EVP_CIPHER *cipher = NULL;
    const void *key = NULL;
    Tcl_Size key_len = 0;


    dprintf("Called");

    /* Get digest */
    md = Util_GetDigest(interp, digestObj, type != TYPE_CMAC);
    if (md == NULL && type != TYPE_CMAC) {
	return TCL_ERROR;

    dprintf("Called");

    switch(statePtr->format & 0xFF0) {
    case TYPE_MD:
        res = EVP_DigestUpdate(statePtr->ctx, buf, (size_t) read);
	break;
    case TYPE_HMAC:
        res = HMAC_Update(statePtr->hctx, (const unsigned char *) buf, (size_t) read);
	break;
    case TYPE_CMAC:
        res = CMAC_Update(statePtr->cctx, buf, (size_t) read);
	break;
    }

    if (!res && do_result) {

    if (!(statePtr->flags & CHAN_EOF)) {
	Tcl_Channel parent = Tcl_GetStackedChannel(statePtr->self);
	Tcl_Obj *resultObj;
	Tcl_Size written, toWrite;

	if (DigestFinalize(statePtr->interp, statePtr, &resultObj) == TCL_OK) {
	    unsigned char *data = Tcl_GetByteArrayFromObj(resultObj, &toWrite);
	    written = Tcl_WriteRaw(parent, (const char *) data, toWrite);
            if (written != toWrite) {
                /* Error */
            }
	    Tcl_DecrRefCount(resultObj);
	}
	statePtr->flags |= CHAN_EOF;
    }

    /* Clean-up */
    DigestStateFree(statePtr);

    /* Abort if nothing to process */
    if (toWrite <= 0 || statePtr->self == (Tcl_Channel) NULL) {
	return 0;
    }

    /* Update hash function */
    if (DigestUpdate(statePtr, (char *) buf, (Tcl_Size) toWrite, 0) != TCL_OK) {
	Tcl_SetChannelError(statePtr->self, Tcl_ObjPrintf("Update failed: %s", GET_ERR_REASON()));
	*errorCodePtr = EINVAL;
	return 0;
    }
    return toWrite;
}

 *
 *-------------------------------------------------------------------
 */
int DigestInstanceObjCmd(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
    DigestState *statePtr = (DigestState *) clientData;
    int fn;
    Tcl_Size data_len = 0;
    unsigned char *data = NULL;
    static const char *instance_fns [] = { "finalize", "update", NULL };

    dprintf("Called");

    /* Validate arg count */
    if (objc < 2 || objc > 3) {
	Tcl_WrongNumArgs(interp, 1, objv, "function ?data?");

	    data = Tcl_GetByteArrayFromObj(objv[2], &data_len);
	} else {
	    Tcl_WrongNumArgs(interp, 1, objv, "update data");
	    return TCL_ERROR;
	}

	/* Update hash function */
	if (DigestUpdate(statePtr, (char *) data, data_len, 1) != TCL_OK) {
	    return TCL_ERROR;
	}

    } else {
	/* Finalize hash function and calculate message digest */
	if (DigestFinalize(interp, statePtr, NULL) != TCL_OK) {
	    return TCL_ERROR;

 * Side effects:
 *	Sets result to message digest or error message
 *
 *-------------------------------------------------------------------
 */
int DigestDataHandler(Tcl_Interp *interp, Tcl_Obj *dataObj, Tcl_Obj *digestObj,
	Tcl_Obj *cipherObj, int format, Tcl_Obj *keyObj, Tcl_Obj *macObj) {
    unsigned char *data;
    Tcl_Size data_len;
    DigestState *statePtr;

    dprintf("Called");

    /* Get data */
    data = Tcl_GetByteArrayFromObj(dataObj, &data_len);
    if (data == NULL) {
	Tcl_SetResult(interp, "No data", NULL);
	return TCL_ERROR;
    }

    /* Create state data structure */
    if ((statePtr = DigestStateNew(interp, format)) == NULL) {
	Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
	return TCL_ERROR;
    }

    /* Calc Digest */
    if (DigestInitialize(interp, statePtr, digestObj, cipherObj, keyObj, macObj) != TCL_OK ||
	DigestUpdate(statePtr, (char *) data, data_len, 1) != TCL_OK ||
	DigestFinalize(interp, statePtr, NULL) != TCL_OK) {
	DigestStateFree(statePtr);
	return TCL_ERROR;
    }

    /* Clean-up */
    DigestStateFree(statePtr);

	goto done;
    }

    /* Read file data and update hash function */
    while (!Tcl_Eof(chan)) {
	Tcl_Size len = Tcl_ReadRaw(chan, (char *) buf, BUFFER_SIZE);
	if (len > 0) {
	    if ((res = DigestUpdate(statePtr, (char *) &buf[0], len, 1)) != TCL_OK) {
		goto done;
	    }
	}
    }

    /* Finalize hash function and calculate message digest */
    res = DigestFinalize(interp, statePtr, NULL);