Spiritus, would you agree that each person has a "right to seek the truth" and to do what is necessary, within limits, to find it? Thankfully, DH at least mentions the that rights are founded in the truth, and apart from that, I think it is primarily concerned with the freedom of Catholics to preach the Gospel and primarily that of the Church.
It is in accordance with their dignity as persons-that is, beings endowed with reason and free will and therefore privileged to bear personal responsibility-that all men should be at once impelled by nature and also bound by a moral obligation to seek the truth, especially religious truth. They are also bound to adhere to the truth, once it is known, and to order their whole lives in accord with the demands of truth
The Church should enjoy that full measure of freedom which her care for the salvation of men requires. This is a sacred freedom, because the only-begotten Son endowed with it the Church which He purchased with His blood. Indeed it is so much the property of the Church that to act against it is to act against the will of God. The freedom of the Church is the fundamental principle in what concerns the relations between the Church and governments and the whole civil order.