I've been a coward and shied away from giving an actual account of how (I think) blockchains work, which isn't very helpful. Sorry.
I think it relies on each 'block' of transactions being summarised using a cryptographic 'hash' - you can't change any of the transactions without changing the hash, but the hash is far smaller than the set of transactions.
The relevant clever bit[1] is that you also include the last block's hash in the data you use to produce this block's hash.
That way, you only need to keep track of the last block's hash to calculate the next block, while still having a 'chain' to follow to verify that each block follows from the last.
In the past year I've probably edited over a dozen white papers
[2]on blockchain and DLT, and even then - if someone were to ask me to explain what blockchain was - my brain would go into spinning pinwheel mode. But yeah, that's essentially it. No one can change the hash without that change being recorded on the hash therefore any attempts to duplicate or compromise the hash will already be encoded in it as a failsafe.
Bitcoin mining is an attempt to 'unearth' ever more complex hashes in that chain, which is why is requires exponentially more processing power to get them. This is known as a proof-of-work DLT, and the rate that Bitcoin is created decreases every four years.
[3]Ethereum uses a proof-of-stake DLT, which (I
think) is what distinguishes it from Bitcoin, in that it can act far more like a normal currency unit. It can be mined, but it can be easily traded (your proof of stake) from the get go, and that seems to be why so many new cryptos are using Ethereum's blockchain (just to make it more confusing, Bitcoin and Ethereum are both currencies and blockchain models, but Ethereum was specifically designed to be an open source DLT model rather than just a currency).
To continue what
we were talking about on the WSB thread:
I don't understand why it would be any different to buying and selling non-digital renminbi.
I'm guessing that, unlike Bitcoin, Ethereum et al - which are permissonless open-node DLTs, CDEP will be a closed node and/or permissioned DLT, possibly even on a private blockchain, at least initially (how else could they keep it localised to Hong Kong?). Chinese fintech is about to take a quantum leap after massive amounts of state investment in AI and machine learning, so whatever they do, it's going to be pretty fucking huge, with potentially global consequences (or at least that's what the white paper badly translated from Mandarin I just read says.)
