#define BUFFER_SIZE	65536
#define CHAN_EOF	0x10
#define READ_DELAY	5

/* Digest format and operation */
#define BIN_FORMAT	0x01
#define HEX_FORMAT	0x02
#define IS_XOF		0x08
#define TYPE_MD		0x10
#define TYPE_HMAC	0x20
#define TYPE_CMAC	0x40

/*
 * This structure defines the per-instance state of a digest operation.
 */

int Tls_DigestFinialize(Tcl_Interp *interp, DigestState *statePtr, Tcl_Obj **resultObj) {
    unsigned char md_buf[EVP_MAX_MD_SIZE];
    unsigned int md_len;
    int res = 0;

    /* Finalize hash function and calculate message digest */
    if (statePtr->format & TYPE_MD) {
	if (!(statePtr->format & IS_XOF)) {
	    res = EVP_DigestFinal_ex(statePtr->ctx, md_buf, &md_len);
	} else {
	    res = EVP_DigestFinalXOF(statePtr->ctx, md_buf, EVP_MAX_MD_SIZE);
	}

    } else if (statePtr->format & TYPE_HMAC) {
	res = HMAC_Final(statePtr->hctx, md_buf, &md_len);

    } else if (statePtr->format & TYPE_CMAC) {
	size_t len;
	res = CMAC_Final(statePtr->cctx, md_buf, &len);
	md_len = (unsigned int) len;
    }

    if (!res) {

 *
 *	 Callback to clean-up when digest instance command is deleted.
 *
 * Returns:
 *	Nothing
 *
 * Side effects:
 *	Destroys state info structure
 *
 *-------------------------------------------------------------------
 */
void InstanceDelCallback(ClientData clientData) {
    DigestState *statePtr = (DigestState *) clientData;

    /* Clean-up */

    /* Get digest */
    if (digestName != NULL) {
	md = EVP_get_digestbyname(digestName);
	if (md == NULL) {
	    Tcl_AppendResult(interp, "Invalid digest \"", digestName, "\"", NULL);
	    return TCL_ERROR;
	} else if (md == EVP_shake128() || md == EVP_shake256()) {
	    format |= IS_XOF;
	}
    } else if (type == TYPE_MD || type == TYPE_HMAC) {
	Tcl_AppendResult(interp, "No digest specified", NULL);
	return TCL_ERROR;
    }

    /* Get key */