Cardinal Van Thuan was imprisoned for many years by the Vietnamese Communists, and it was known that he celebrated Mass by himself in the prison. The question is, how did he celebrate mass exactly? Did he have the Liturgy of the Word, the prayers after the Eucharistic Prayer etc.? This, all in all, leads to the more greater question, what is the minimum required for a valid Mass? Do the words of consecration, with the bread and wine suffice?
Even under extraordinary circumstances, no, the words of consecration alone would not suffice. It would actually be a grave crime. Canon 927 states:
“It is absolutely forbidden, even in extreme urgent necessity, to consecrate one matter without the other or even both outside the eucharistic celebration.”
The word used in the Latin original, nefas, is a lot stronger than the translation - it indicates that it is so horrible that it is unthinkable. It is the same word which is used about priests violating the seal of confession.
However, I do not know the specifics regarding how Mass was celebrated in Vietnamese labor camps, and it would be uncharitable for me to presume that they in any way violated canon law or the (most essential) rubrics in how they celebrated Mass. Knowing Vietnamese priests, I highly doubt they did. And it wouldn’t be necessary - it is for example completely possible to remember all the prayers of a votive Mass by heart. Under such circumstances, it would be much better to say a votive Mass than no Mass. According to a priest I know who celebrates the older form of Mass, it even used to be an ideal (or even a requirement, but I’m not sure about that) that a priest should know the Ordo by heart, so the Mass could be celebrated under such circumstances! There is nothing wrong with “stripping down” the Mass or improvising from necessity, as long as the absolute requirements are still followed. That consecration take place within the Order of Mass is the most important of them.
So, what are the absolute requirements?
Obviously, in a prison situation, the priest would not have access to an altar, or to the sacred vessels, of vestments. He must do the best he can. He must have bread and access to wine. (If I remember correctly, Cardinal Van Thuan was able to obtain some wine fairly regularly, for medicinal purposes).
Most priests, if not all, ensure that they can recite all the unchanging prayers of the Mass from memory (in a recent visit to my 85 year old brother, he told me he was using Eucharistic prayer II regularly in order to be able to use it, should he not have access to a Missal at any time in the future).
If an imprisoned priest has access to a Bible or a Breviary, he could use this for readings, etc., but otherwise, he would have to use any suitable prayers he can remember for the collect, offertory prayer, etc.
So, the requirements? Bread, wine, the priest’s own good memory and piety.
Why would one need access to bread AND wine? I have never taken the wine because I don’t like drinking after people. I heard of a girl at my parish that only takes the wine as she is allergic to gluten. The body and blood is in both species. And there’s a metaphysical explanation for that I forget what it is. But anyway transubstantiation does not alter the accidents but changes the substance. I would not call having bread and wine a requirement but I may be wrong. I’m not clergy.
No one except the priest is required to consume the species.
Because consecrating the one without consecrating the other is a serious crime, see can. 927.
It is true that communion under one kind is fully permissible and actually in many ways the norm of the Latin Rite, but the priest has to consecrate both as well as consume both.