function result=randlsbget(output,len_total,goalfile,key)
ste_cover=imread(output);
ste_cover=double(ste_cover);
[m,n]=size(ste_cover);
frr=fopen(goalfile,'a');
p=1;
[row,col]=randinterval(ste_cover,len_total,key);
for i=1:len_total
    if bitand(ste_cover(row(i),col(i)),1)==1
        fwrite(frr,1,'ubit1');
        result(p,1)=1;
    else
        fwrite(frr,0,'ubit1');
        result(p,1)=0;
    end
        if p==len_total
            break;
        end
        p=p+1;
end
fclose(frr);