*/
int
HashCalc(Tcl_Interp *interp, int objc, Tcl_Obj *const objv[], const EVP_MD *type) {
    char *data;
    int len;
    unsigned int mdlen;
    unsigned char mdbuf[EVP_MAX_MD_SIZE];
    unsigned char hashbuf[EVP_MAX_MD_SIZE*2+1];
    const char *hex = "0123456789ABCDEF";

    if (objc != 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "data");
	return TCL_ERROR;
    }

    /* Get data */
    data = Tcl_GetByteArrayFromObj(objv[1], &len);
    if (data == NULL) {
    if (data == NULL || len == 0) {
	Tcl_SetResult(interp, "No data", NULL);
	return TCL_ERROR;
    }

    /* Calc hash, convert to hex string, and write to result */
    /* Calc hash value, create hex representation, and write to result */
    if (EVP_Digest(data, (size_t) len, mdbuf, &mdlen, type, NULL)) {
	Tcl_Obj *resultObj;
	unsigned char *mptr = mdbuf;
	unsigned char *hptr = &hashbuf[0];
	unsigned char *ptr;
	resultObj = Tcl_NewObj();
	ptr = Tcl_SetByteArrayLength(resultObj, mdlen*2);

	for (unsigned int i = 0; i < mdlen; i++) {
	    *hptr++ = hex[(*mptr>>4)&0xF];
	    *hptr++ = hex[(*mptr++)&0xF];
	    *ptr++ = hex[(mdbuf[i] >> 4) & 0x0F];
	    *ptr++ = hex[mdbuf[i] & 0x0F];
	}
	*hptr = 0;
	Tcl_SetObjResult(interp, Tcl_NewStringObj(hashbuf, mdlen*2));
	Tcl_SetObjResult(interp, resultObj);
    } else {
	Tcl_SetResult(interp, "Hash calculation error", NULL);
	return TCL_ERROR;
    }
    return TCL_OK;
}