BIGNUM *getbnfrombuf(const unsigned char *buf,size_t len)
	{
	while (*buf==0&&len>0)
		{
		buf++; len--;
		}
	if (len)
		{
		return BN_bin2bn(buf,len,NULL);
		}
	else
		{
		BIGNUM *b=BN_new();
		BN_zero(b);
		return b;
		}
	}