"Please do!"

So Cam can explain about how he can make arbitrary things and this dooms all physical currency but with sufficiently attended-to cryptography various digital systems may remain alive and well, and you could probably substitute some suitable magical signature deal, and also daeva are okay but not as good as wizards at disguising themselves so if you recognize someone you can figure with as much confidence as you normally have that they are them, blah blah blockchain blah blah retina scans blah blah when there are this many demons around you can have them verify things on your end as-needed.

The Deputy Ambassador is relieved that Cam understands the importance of not destroying the economy but disconcerted by the sheer number of daeva. He asks a bunch of questions about privacy laws and intellectual property rights and contract dispute resolution, and calls in another, less elaborately dressed goblin who asks some extremely technical questions about the crypto and the blockchain.

Cam can answer questions and supplement as necessary with written materials.

His ability to conjure information he doesn't know about leads to some sidelong glances and muttering in Gobbledegook and then even more questions about data encryption.

"The state of the art in demon-proof encryption is the chip-locked computer. I have one myself. They can be installed safely - by demons, or less safely by conventional surgery - in humans. They use the habits of a person's brain to encode data and have yet to be hacked. I don't know how hard it would be to adapt them to non-human non-daeva persons."

This calls for the summoning of another subject matter expert to discuss whether this can be replicated by magic, because brain surgery designed for humans sounds like a terrible idea. Maybe you could do something like a simplified, stripped-down Pensieve with a tablet-and-stylus form factor? Communication with anyone who isn't in the same room is going to be the tricky bit. Can Cam's abilities intercept, for example, a Muggle telegraph?

"It depends. If it's written at either end, we can get that. If it's transmitted electrically by people who speak it out loud to translate, or it's semaphore or something, we can get it, but it's substantially harder, because we have to get the state of the transmission at each point in the relevant timespan and decipher it from there."

The crypto guy calls in three more presumable crypto people, tells them something in a mix of Gobbledygook and sign language, and then shoos them out again. Rangvald says, "We appreciate your cooperation with all of this. Eventually we would like you to confirm under veritaserum that you haven't misrepresented your own or your species' abilities."

"Uh, I picked up Occlumency a while back out of an abundance of caution and have tested it on Veritaserum, which I beat. I can just demonstrate the abilities themselves more if you like."

This gets an expression of mild annoyance, but it doesn't appear to be directed at Cam. "That plus a demonstration of your ability to lie under Veritaserum should suffice." He writes something on a piece of paper, rolls it into a tube, and sticks it into a hole in the wall, which inhales it. "The Veritaserum will be delivered shortly. In the meantime . . ." Rangvald proceeds to ask for conjurations of various things, some of which are secretly nonexistent or contradictory and many of which involve references to things like "the number of fingers Rangvald is holding up, some of which are under the table".

Cam conjures little dioramas, narrating as he does about what conjurable parameters he is using.

Eventually Rangvald is satisfied that Cam is telling the truth (or significantly smarter than Rangvald, or concealing several additional powers).

"Do you have a timeline in mind for introducing additional demons to this plane of existence? And how much have you told any wizarding governments? It will affect how quickly we need to redesign our operations."

"I have not been in contact with any wizarding governments at all. I haven't been keeping many secrets from people I meet at Hogwarts, though. I've been planning to see if there's anything worth joining forces with in existing anti-secrecy movements to reduce impediments to a revelation of how to get more daeva assistance here."

"You're thinking of informing the muggles?"

"The Muggles are the ones who'll benefit the most, even if there weren't orders of magnitude more of them!"

"The question is whether they'll see it that way. In a large enough group of people, someone is going to act erratically."

"Yes, but we're comparing here to not doing anything and allowing billions of people to continue to live in poverty dying of preventable diseases."

"Understandable. I am, in this as in all things, primarily concerned with the security of the Goblin nation."

"That's very reasonable of you. I don't know very much about the Goblin nation so I can't predict very confidently what the results of daeva being generally known will be for you folks specifically."

"The worst case scenario is that the muggles and the daeva ally with the wizards against us. I of course cannot speculate on our preparations for that case, but do you have an estimate of its likelihood?"

"I don't actually know much about wizard-goblin tensions. I wouldn't estimate it as very likely on general principle, though, genocide gets bad press."

"This is admittedly a better time for it than much of the last century."

"Oh yeah, I would be far more hesitant to recommend this fifty years ago."

"Indeed. I notice you never gave an estimate for the timetable."