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nxt checkpoints in code (CHECKSUM_BLOCK_X)
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Author Topic: nxt checkpoints in code (CHECKSUM_BLOCK_X)  (Read 443 times)

junga

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nxt checkpoints in code (CHECKSUM_BLOCK_X)
« on: April 16, 2018, 09:02:28 pm »

In src/java/nxt/Constants.java we can see few checksums for specific blocks CHECKSUM_BLOCK_X.
What are they used for? defending against "nothing at stack" attack?
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Right.Here

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Re: nxt checkpoints in code (CHECKSUM_BLOCK_X)
« Reply #1 on: April 16, 2018, 10:43:06 pm »

Hi  :D
In src/java/nxt/Constants.java we can see few checksums for specific blocks CHECKSUM_BLOCK_X.
What are they used for? defending against "nothing at stack" attack?

those are here to avoid the blockchain forks and forking... security stuff...
(for the NBCK... you must add yours on each release...)

Thank you for asking  :D
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junga

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Re: nxt checkpoints in code (CHECKSUM_BLOCK_X)
« Reply #2 on: April 17, 2018, 01:36:19 pm »

Hi, Thank you for the fast answer.
1) Can you please explain what this is meant to prevent? a fork can happen at all the times, why is it important to add it in each release. In other words, can you please give more details about "security stuff"?
2) Sorry, but what is NBCK?

Thanks
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Right.Here

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Re: nxt checkpoints in code (CHECKSUM_BLOCK_X)
« Reply #3 on: April 17, 2018, 08:55:21 pm »

Hi  :D
Hi, Thank you for the fast answer.
1) Can you please explain what this is meant to prevent? a fork can happen at all the times, why is it important to add it in each release. In other words, can you please give more details about "security stuff"?
2) Sorry, but what is NBCK?

Thanks

I'm not a guru in the matter but according to what I understood from my reading of the code is that there is a forks detector that triggers rescan and checks when it detects something abnormal in the blockchain, it can even recompose the blockchain from block 0 until today if he detects a major fork ...

in the early days of the platform, the blockchain is small and can be rescanned in its entirety without disturbing the functioning of the system ... but when the blockchain grows over time, the system has much more work because it has to manage Go of data as for NXT + 2.7GB ...

so if we know for example that until block X (close in time) the blockchain is clean and the checksum is correct ... it is useless to rescan and verify the data before this block and we can give the system a new starting point for checks and less unnecessary work ...

that's why the CHECKSUM_BLOCK_X .... at least that I think

I deduced from your questions that you are trying to clone NXT using the NXT software and pack?!? if so, stop because you are doing the wrong thing  ;D

jelurida has released a devlopement kit for those who want to create a platform like NXT ... and it's easier and already tidy of all the things that serve only the NXT platform:
https://www.jelurida.com/blockchain-creation-kit

the NXT Blockchain Creation Kit or NBCK  ;)

enjoy and good continuation  :D
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junga

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Re: nxt checkpoints in code (CHECKSUM_BLOCK_X)
« Reply #4 on: April 18, 2018, 07:33:37 am »

Hi,
Thank you for the answer.
I deduced from your questions that you are trying to clone NXT using the NXT software and pack

Actually, I asked it since some people say that POS is broken, and the way NXT went around "nothing at stack" is by using "centralized" checksum (CHECKSUM_BLOCK_X) placed by the developers.

So, from your answer, I understand that it is meant for performance, and not for security.
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