Transactions: How to send Bitcoins programmatically without requiring a local blockchain copy?

I am quite new in the development of Bitcoin! I have seen the documentation on RPC commands, available when you have a local blockchain copy.

But I would like to know if it is possible to create and transmit send transactions in the Bitcoin network without a local blockchain copy?

I use Java, but I try to avoid using Bitcoinj. Currently, I try to understand how everything works under the hood. I can create new addresses, with their associated private keys (without formatting and WIFformats). That works well!

Using the API provided by blockchain.com, I can get information about those addresses and know if they have received coins.

The only part that is missing for me is to find a programmatic way Send some coins from those addresses to other addresses, without a local copy of the blockchain (and using RPC calls on it).

I see blockchain.com It also provides a Wallet API but, correct me if I'm wrong, when using this they control private keys right? I would prefer a way to send coins creating and signing transactions in the zone and then I transmitted them, just … Without a local blockchain.

It's possible? What are the options?

blockchain – Bitcoin has asked me to send money for a private key

Hello, I have been asked to send money for funds that are not eligible to receive a private key to unlock it, it is investment in bitcoins. How safe is this since I worry about not receiving payment? It is currently in my blockchain wallet account and shows the funds as non-expendable until they are unlocked with a private key

Blockchain Explorer says received but has not yet been received!

I sent some Bitcoin to my friends wallet for 2 days. It says approved and sent successfully by me. And even in blockchain Explorer it says confirmed and received. But my friend says he hasn't received Bitcoin yet? This is the transaction ID in blockchain Explorer

https://www.blockchain.com/btc/tx/d350a1334d10e7693b56cc8fd8d11297080e1aebd9ffed97588a4b5f0929ca93

A blockchain that combines mining forks and could be more energy efficient?

I am new to blockchain technology, so sorry if I am using incorrect terminology. This is not a Bitcoin question, but a general blockchain question.

Imagine a theoretical blockchain that uses a gradual work test, instead of finding just one nonce that gives a hash smaller than the target, you have to find 10 nonces that give hashes that are smaller than target * 10.
(Edit: a more complicated algorithm can be used, for example, the first hash includes the block header and the first nonce, the second hash includes the
block-header, the second nonce and the previous hash, etc., so the calculation of the hashes cannot be done in parallel).

If you discovered 9/10 good then, you will try to find the last nonce even if some other miner has already published a complete block.
This type of blockchain will encourage arbitrary mining holders, where two miners publish a mined block with the same hash of the previous block (that is, the same index in the chain), which looks like this:

B1  ←-  B2  ←-  B3  ←-  B4
                ↑
                +-----  B4'

The way in which the current block chains (which I know) solve this problem is by letting the miners choose which of the forks to continue, and because only the longest block chain is the "true block chain", all Miners will eventually work on a single fork, and all work done on the other holders will be in vain.

Now imagine that each block could contain more than 1 hash of the previous block. For example, a new miner might try to extract a block such as:

B1  ←-  B2  ←-  B3  ←-  B4  ←-  B5
                ↑               |
                +-----  B4' ←---+

With an important condition: transactions in B4 should not contradict transactions in B4 & # 39; (without double expense, etc.). Assuming there are many unrelated transactions in the mempool, this will be a very common scenario.

You can even encourage miners to include more hashes from previous blocks in the next block. For example, if the miner of B4 & # 39; realizes that B4 has already been published, he may offer to pay a fee to the following miners (of B5) who also include B4 & # 39 ;.

This algorithm will be much more energy efficient (in the case of a gradual work test) because miners can continue to mine the same block even if some other miner has already found a good block. You can extract more transactions in parallel without increasing the block size. It is different from choosing an easier hash function (for the work test), because it has no effect on the length of the blockchain or the speed of growth.

Do you know any blockchain / cryptocurrency proof of work that does something similar, like a blockchain that can be divided and merged? I know that IOTA is not using blockchain at all, but I never delved into the details.

Thank you

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blockchain: how can I know that my transaction has been confirmed in the longest chain?

Building a chain longer than the best chain would require someone to have more Proof of Work hashpower than 51% or more of the total hashpower of the Bitcoin network.

The improbability of this happening is the guarantee that the longest chain is the best chain.

To build a longer chain of a block, you would have to assemble a block and find a nonce that produces a goal less than or equal to the goal of the network. Otherwise, Bitcoin Core will discard your lock as invalid. So, to build a chain that is only 1 block longer than the best current chain, you would need large amounts of hashpower, electricity, infrastructure and tens of millions of dollars of investment. Again, all this for just one block.

The astronomical amount of work done in the mining of each block protects the Bitcoin consensus mechanism and assures everyone that the longest chain is correct.

If your TX was included in a block with depth 6, it means that for approximately one hour (~ 6 x 10 minutes blocks) that chain where the block containing your TX was included had the most work in the world.

There could be Some another place where someone created an artificial chain with its TX in it, but that chain can never be longer than the main chain, unless they beat the network to find the next block. If they can't do it, then that chain will be ignored by everyone else on the network. This is how you know that the TX you see in block explorers is in the longest / best chain.

For a more detailed answer, you should read Antonopoulos's book (Mastering Bitcoin).

bitcoin core: output tree not used in blockchain

I have been reading about the security of thin clients and I found the section that discusses the proposed unused output tree in the blockchain.

Output tree not used in blockchain (UOT)
There have been several proposals (the first seems to be that of gmaxwell, who called it an "open transaction tree", although the term "open" is now taken as "not yet exploited in the blockchain" instead of "not spent "") to form an unused transaction output tree in each block of the chain, encode it as a Merkle tree and encode the root hash in the blockchain (probably as part of the coin base entry). It will be called an unused output tree (UOT). The first proposal detailed so far seems to be Alberto Torres' proposal; the final compression of the etotheipi blockchain is a variant of this.

If such UOT hashes were included in the blockchain, a client that was sent with a checkpoint block that had a UOT would only need to download blocks after the checkpoint. In addition, once the client has downloaded those blocks and confirmed their UOTs, they could discard all but the most recent block containing a UOT.

I understand this part and how the merkle tree is going to be built, but the next part that talks about the associated risks is what confuses me:

Hostile miners can insert blocks in the chain that have what they claim to be a UOT, but that is not really valid. It is unlikely that such blocks can be kept out of the chain because, again, this would require adding a new block validity criteria, and miners who implement this new criterion would risk "mining on the wrong side" of a fork, which could cost them a lot of money. Therefore, any UOT strategy would need to deal with the fact that not all blocks containing a UOT entry can be trusted.

So my questions are:

  1. I suppose an invalid UOT means a tree that contains outputs that are double spending or that do not even exist in the chain. Why could the bitcoin network not reject them? Are complete nodes also vulnerable to this attack? I think that the complete nodes can always check the outputs in the UOT against the previous ones to ensure that all the outputs are included in the previous UOT or generated by transactions in the current block.
  2. I understand that implementing this would require some modifications to the current validity criteria, could buying nodes that take these changes risk "mining on the wrong side"?

Send data to bitcoin blockchain

Is it possible to send a transaction containing hash values ​​in the body to anyone? I explain you better. I would like to store data in bitcoin and would need to send a transaction that contains this value but not to a specific address. Could do it?

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A Blockchain It is a decentralized, digitized public book of all cryptocurrency transactions. Blockchain technology was developed to support bitcoin in digital currency and is considered the most competent technology against cyber fraud that accepts financial transactions to be verified electronically through a computer network. With this technology, we can perform any type of transactions without using centralized servers. We, at Osiz Technologies, are leaders blockchain development company offers wallet, IPFS, smart contracts, poc, private and public blockchain application development services for all types of business solutions that use blockchain technology. Hire dedicated blockchain developers for your next blockchain application development projects. We have written a blog that shows that industries use blockchain industries. For more information, visit this URL, https://www.osiztechnologies.com/blog/enterprise-blockchain-development-company

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