If I secreted this, you would all read it anyway and be irritated for such a lot of reading in an irritating color, so I won't.
Beethro and Bombus select a suit order (Say spades, diamonds, clubs, hearts) so the cards are essentially 1 through 52 (Aces are low) and they are aware that 4 cards have 24 permeutations and know the same logical order for counting them (labelling cards lowest to highest 1234, 1243, 1324, 1342, etc.). All familiar so far, eh? However, when Bombus gets the cards, he notes which card is the highest card (wherever it may be in the order) and uses that as his zero point and counts off the permeutation to the secret card, modularly looping around the deck order if he needs to. Beethro will have chosen the target card and order accordingly. Not all of the cards in a hand of five can be a target, but all will contain at least one. Proof: the five cards will be roughly every 10.4 cards of the deck by probability and therefore a card will easily be in the 24 target range of another card, so bunching distributions must be bad. The worst would be five in a row, but then the highest card is target, and second is zero point, use first pereutation, no problem. If four are together and one is substantially higher it has to be at least 25 cards away to not be hit. If it is it can't be the chosen target and will have to be the zero point if not chosen as target. However, the low cards will be in range because those 4 plus a 25 card distance plus 24 card range is 53 cards. Meaning in worst case scenario, you pick the lowest card as target and are just able to hit it.
Lots of writing, but just a bit more, an example: I have a real deck and am randomly shuffling...
4H, 8S, KD, 6C, 3C
I can pick 4H or 8S as target, nothing else. If I pick 4H, 6C is zero so I encode the number 11 which is 2413 or KD-6C-8S-3C. If 8S, 4H is zero and it is 17 cards (modulo 52) to 8S. This is 3412 or 6C-4H-KD-3C.
Wow. Beethro and Bombus are smart dudes!
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Vectors are pretty cool, they take your mind off of girls.