The link “https://web.archive.org/web/20191001083147/https://www.coindesk.com/information/what-is-segwit” returns a “504 Gateway Time-out” status for me. It tried different browsers. Is the link bad?
you have 2 links added together. separate them at https…
No, it’s a web archive link. That’s why it’s a link within a link.
When I try it it works fine, is it still not working for you? @Pellerin
You’re right.
I have no problem opening the link.
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I don’t think I’m completely following the magnitude of the malleability threat. Even if Bob were to alter the signature, isn’t it only within his own node initially and then propagating it out to other nodes? For Alice, her own node and other nodes she propagated to would still have the original Tx ID, no? Or am I mistaking something here?
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Before a transaction is included in a block, the transaction is in the mempool synced with all nodes. because signatures were included in de hashing to create a transaction ID, the Transaction ID can change wich you can mislead people. the original transaction ID will be replaced with the new one, because all nodes will hash the transaction to make a transactionID
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Originally tx malleability was not an significant issue?
It was considered a kind of bug in the protocol?
For novice like me, it sounds very vulnerable from the very early stage of the BTC network
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it was an issue since the beginning, because you could mislead noobs who check on a Tx-ID for payments
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It appears as if the video will not play after 7 min 10 seconds
Hey @filip correct me if I’m wrong, but in the reading assignment, the coindesk article doesn’t really explain why Segwit and the Lightning Network are connected.
Also maybe I missed in which lecture this is explained?
Thanks for enlightening me, cheers
Oh I see what happened. The article was removed from coindesk and instead you get redirected to some other blockchain article. While we search for a new article to include, you can use this archive link to find the old article: https://web.archive.org/web/20191001083147/https://www.coindesk.com/information/what-is-segwit
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I do have a question Filip. When the hash is created what factors compose the hash. Is the encryption hash based entirely off the signature and transaction or are more factors like time place and ip address involved?
The hash only uses the transaction as underlying information, not any external data like place or IP.
I have a better understanding of segwit, In the beginning I was thinking it was a programming language. Thanks Filip.
ok i understand that the sign is sent with the tx but it is not hashed, so if someone wants to change the sign will not change the txid as it is not info that is hashed.
if it goes separattely but in the same block but without being hashed how is this decreasing the block size as it is still in the blocks?
Hi guys, I like your classes but I have to say that I had a lot of issues with this one on Segwit. Below I tried to describe these issues hoping that you can clarify for me:
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After this course it is unclear to me how a Segwit transaction is constructed. It would be very helpful to have a step by step description of how a Segwit transaction is constructed (showing what elements are included in the transaction, what is hashed with what, when and how is the transaction signed, how is the separate signature block created, how the linkage between the transaction and the signature is preserved despite the fact that they are placed on 2 different blocks, etc.).
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In a Segwit transaction, why is there no impact on the transaction if someone changes in the signature block?
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It is stated in the article that Segwit enabled Lighting network and smart contracts… Why is that and how is it achieved? Were we supposed to understand this when reading the article or is this explained/covered in subsequent classes?
Malleability in itself was also very challenging to understand for me. I felt that you went a little too fast through this part, because you mentioned very briefly certain aspects which were very disconcerting and which I needed to have explained before moving to the next things:
- For example, I didn’t understand how it was possible for Bob to change Alice’s signature in her transaction? This is not trivial at all for me, that you can actually go and edit/modify/rewrite a transaction after it has been sent to the network…
- If you can edit the signature, why can’t you also edit the rest of the transaction data like for example “who pays who” and “how much”?
- In the article it is stated that the Malleability issue is not critical for bitcoin. How is it possible that it is not considered critical? Is it not critical that anyone can change the transactions and steal others’ bitcoins? How is it possible that people used the bitcoin network all this time and made payments on it, despite knowing about this issue? It’s very confusing… I feel I am completely missing something…
I hope you can clarify these questions for me 
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@filip thanks for good explanations of this complicated topic. Still have one more question. If segwit removes signatures and saves some space, but amount of txs are growing, it’s still gonna reach that limit, when 1MB block limit is too low. It looks like a temporary solution, or I misunderstand something?
Yes, it’s not a final solution, but most important part of separating the signature in a different data structure is to solve the malleability problem. so because of segwit we could build the lightning network on bitcoin wich scales it much bigger. But on chain transactions have a limit. But don’t forget that using segwit addresses takes much less space and has much less fee required.
the blocks itself can be more than 1MB, but only the part with the transactions ect has to be lower than 1MB.
Scaling is one of the biggest debates in bitcoin 
If you want to know more about the weight units of different types of transactions, check this:
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How do you let miners know about an update and is there any miner forum where they can discuss such things in order to reach a consensus and avoid rifts and miscommunications within the community?