Blockchain - Sicherheit auch ohne Trust Center

1. 00:00Let's take a look at Bitcoin's idea now, as suggested by Nakamoto.
2. 00:07This idea assumes that you have a banking system, a money system, a cash system, a money system, without a bank.
3. 00:21That's blockchain-based, and the thought, why it's even interesting to think about it, whether the banks are really vital in such a monetary system,
4. 00:33was because, of course, at this time when it was proposed, 2008, just the international banking crisis was and confidence in the banks was severely shaken.
5. 00:43And for the exchange of money and transactions trust in the bank is, of course, central.
6. 00:49If anyone can say no, no, I don't believe it, then there'll be a fight forever and it's not clear.
7. 00:54No one would pay money in such a system. or want to receive money.
8. 00:59So the idea is described here in this paper "Bitcoin: A Peer-to-Peer Electronic Cash System is,
9. 01:07to build a money system, a cash system, without a central anchor of trust like the banks.
10. 01:17But a peer-to-peer network, i.e. many participants who do not know each other, so first of all, don't trust each other through a mechanism, an algorithm, mathematical mechanism,
11. 01:30to create a situation of trust where the participants are willing again, to transfer and receive money, and trust the system as a whole.
12. 01:41So this paper is this Satoshi Nakamoto - that's probably a synonym - that is the basis and the foundation for the first generation of blockchains
13. 01:56and the first generation of crypto currencies on which it was built, to think about, is that only true in the banking sector?
14. 02:05There's no such thing as applications in other areas, where one can dispense with a central trust anchor via the blockchain technology.
15. 02:14The messages exchanged in the Bitcoin system. between the participants, that's transactions.
16. 02:22So I'm transferring so many bitcoins to you, I'm receiving so many bitcoins from you, and the basic idea is the block chain is needed, because that's where all the transactions are archived.
17. 02:34We've learned about mechanisms, the linked timestamps, as we can make sure,
18. 02:40that the order of the transactions is determined, so that the participants in such a Bitcoin system can also trust each other,
19. 02:51that this was actually the time sequence, the order of the transactions. and that they can trust that that's not rigged.
20. 03:01So what the task of the blockchain is that in the blockchain and guaranteed with the mechanisms around it,
21. 03:10all participants are guaranteed that messages, in which case transactions cannot be subsequently manipulated.
22. 03:19So that's essential, or a money system like that wouldn't work.
23. 03:25That's not Nakamoto, he's in court denying it, but he's become a face.
24. 03:34That's Satoshi Nakamoto. They puzzled, of course, because the Bitcoin system became so big, so popular, so many fantasies, Speculation was triggered there, too,
25. 03:50you said, of course, who came up with the ingenious idea, and then they found a Satoshi Nakamoto, and even published the picture in the big newspapers.
26. 04:00Then he went to court, said, no, no, I'm not, so the story behind it may not matter,
27. 04:08the central idea in this paper by Nakamoto is this consensus algorithm.
28. 04:14The consensus algorithm that is used to achieve that the participants in this cash system, in this payment system, in this Bitcoin system, trust each other.
29. 04:24The consensus algorithm, it has to create the possibility, to tolerate Byzantine errors, so to make fraudulent behavior impossible.
30. 04:38So he can't stop the individual participant from trying to cheat, but through this mechanism. cannot be transferred to the network.
31. 04:51We had discussed this in the first week.
32. 04:53We had seen that with these democratic consensus algorithms. this Sybil attack that there is a participant multiple digital identities that we can prevent.
33. 05:10In this consensus algorithm of Nakamoto, the proof of work proof is that makes it possible, that offers security,
34. 05:24is accepted to provide the assurance that a participant will provide evidence, to really be a participant and not a cheater.
35. 05:32And the system as a whole behaves as a Contingency Consistent System.
36. 05:40There's a certain amount of time it takes to tell the truth. the sequence of the transactions and the content of the transactions also be ensured for all network participants.
37. 05:56So the basic idea of Nakamoto with the consensus algorithm, which made this Bitcoin currency possible.
38. 06:07The first blockchain-based crypto currency went online in 2009, and that has then been a template with various enhancements
39. 06:19for a whole bunch of other crypto currencies, that we know and experience today.
40. 06:25But the basic idea of blockchain and the first application of a blockchain technology, which can be seen here in the banking environment at Bitcoin.
41. 06:38Developed, perhaps also there again a few words to, is in the environment of the so-called Cypherpunks,
42. 06:46the general distrust of instances, of middlemen, which must be trusted, as in the case of the monetary system, the financial system, banks, but also government organizations or others,
43. 07:02there's been a strong motive for not having to rely on that trust, but creates mechanisms, algorithmic mechanisms,
44. 07:13mathematical methods that generate trust and not that there's an instance per se that's trusted.
45. 07:21We had seen the whole thing too, with these chains, the linked timestamps have to be somewhere start with the first block, followed by everything.
46. 07:36And with cryptographic methods, if you wanted to manipulate it, one would also have to manipulate the previous blocks retroactively.
47. 07:47So the contents of this Genesis block, published in the Times on January 3, 2009, with the information "Chancelor on brink of second bailout for banks" in Great Britain.
48. 08:07And then all the transactions are based on that, all the messages in the Bitcoin network are cryptographic are welded together using such hash processes.
49. 08:20So first welded together, then welded in blocks, the blocks are welded together with mathematical methods,
50. 08:30and for generating such blocks, that is then the archived truth, a proof-of-consense approach is chosen.

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