What’s the magic key version bytes for BIP49

I’m implementing BIP49-compatible key derivation for bitcoin-s, but I’m having a hard time finding the magic version bytes to use for the extended keys.

I’ve been looking at BIP49, but can’t find anything there.

Also, is there multiple schemes for deriving P2WPKH-nested-in-P2SH? I’ve been looking at the Samourai fork of BitcoinJ, Trezor’s implementation and the test vectors in BIP49, and I can’t get the vectors to pass by using the magic version bytes from Trezor/Samourai.

Maybe I’m confused by which magic bytes from Samourai corresponds to mainnet/testnet P2WPKH-nested-in-P2SH, so any clarification is appreciated here. From my understanding, the mainnet version bytes are 0x049D7CB2 (pub) and 0x049D7878 (priv) and testnet are 0x044a5262 (pub) and 0x044a4e28 (priv).

As a final thing, any pointers to test vectors for BIP49 and BIP84 is appreciated. Currently I’ve come across the BIPs themselves, as well as SLIP132.

Following SegWit implementation, is BIP-146 signalling and implementation still on the docket?

Is BIP 146, which defines using the low S value, still on the docket to be signalled and implemented given that SegWit fixed the txid malleability issue by moving the witness outside the transaction? I’m asking because it can fix the wtxid malleability which now requires re-syncing of transaction data when it is changed from what it was originally relayed.

Also, will the implementation be a soft-fork which would treat this transactions as non-standard but miners can still include them in the block, or will it treat the transactions with high S value as invalid?

How do cryptocurrency exchanges work with so many currencies at the same time?

To implement automated deposits/withdrawals of a single currency for a business there has to be a lot of code in place specific for that currency. For example if I want to automate sending and receiving bitcoin – I would write an application around bitcoin’s software – bitcoin core. Obviously, there won’t be similar node software for every coin, say Ethereum, would have a different core, if it even has one (it’s an example). Would you need to write a new app that would adapt for that core? Then does it mean that big exchanges write new software that does the same job but for each coin? Where did I go wrong here, or is cryptocurrency development really this complex?

19 out of 24 words of BIP39 passphrase (brute-force last 5?)

I have managed to lose 5 words of my 24 word Ledger Nano S recovery phrase. I have words 1-19 but I am missing words 20-24.
I have significant holdings on the wallet so would very much like to recover it if possible.
The passphrase is a BIP39 mnemonic (see https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki).
I have the bitcoin and ethereum public addresses for this mnemonic. I am wondering if it’s feasible to brute force the passphrase.

Each word is 11 bits (2^11 = 2048 possible words).
The last (24th) word of the passphrase is of the following form [3 random bits][8 bit checksum].
Therefore I only have to check 2^(55 – 8) = 2^47 = 1.4×10^14 combinations.
I would have to compute SHA-512-HMAC with an iteration count of 2048.
As far as I understand, that means I’d have to compute 1.4*10^14 * 2048 = 2.87*10^17 hashes in total.

Is there any hardware out there designed for this? I am aware of ASICs that compute sha-256 hashes but not sha-512 hashes.
Perhaps I could tweak one to work with sha-512 since they are very similar.

Assuming a fairly typical ASIC hashrate of 1TH/s (10^12 hashes per second), I could exhaust the search space in 2.87*10^5 = 287000 seconds = 3.3 days. I’d probably get there sooner, of course (expected 1.65 days). Time is not something I am worried about. Even if I have to wait months, I don’t mind – so if I can get 10GH/s at a reasonable price, that would be great.

I would really appreciate any help/information you could provide to help me out and make sure I haven’t missed anything.
I could also use GPUs for this (I calculate I can run them at roughly $1/10TH – so it would cost me $28.7k to exhaust the search space, which I will do if there are no cheaper options).

Many thanks,

What are the major technical differences between Bitcoin and Bitcoin Cash?

For a research project I’m trying to detect the major technical differences between Bitcoin and Bitcoin Cash. I know that BCH uses a larger block size and does not support SegWit. But what other differences are there?

I know this is a broad question – I’m looking for an overview only, not an exhaustive, detailed list.

In particular, but not exclusively, I’m interested in:

  • Which features are only implemented in one of both chains?
  • Do the data structures differ (blocks, transactions, inputs, outputs)?
  • Is there a difference in which script instructions are supported?
  • What about addresses and address types?
  • Do both chains commonly implement the same BIPs or are BIPs usually exclusive to one chain? Is there a list of which BIPs are implemented in which chain?
  • Overall, what’s the best approach to track past and future changes in both chains? Can you recommend any resources on that issue?

Finding differences by looking at the code does not seem practical to me given the time it’d take me to pinpoint and understand all changes. I used git log --oneline master --reverse on both chains and diffed the results to get some insight, but it’s still hard to detect changes that are relevant to me.

Could Neutrino technically as side-effect, incentivize centralization of the bitcoin network?

TWO questions on Neutrino::

1) Could Neutrino technically as side-effect, incentivize centralization of the bitcoin network? Or other formulation: …hinder higher degree of decentralization?

Why I am asking: This article by Dorier pointed me to this thoughts. https://medium.com/@nicolasdorier/neutrino-is-dangerous-for-my-self-sovereignty-18fac5bcdc25

He basically says neutrino users are still not FULL NODES. Therefore doesnt make sense to switch from SPVs or webwallets to neutrino enabled wallets….

Could the technical knowledgable members here maybe do an explanation, why Dorier might come up with this thesis, what technical arguments are speaking for it? Or do you think its a baseless thesis?

2) He basically says, why do we need neutrino, its essentially the same as SPV… Why is there technical advantages with Neutrino, what are its differentiators to SPV?

Thank you