Questions tagged [transaction-verification]

Refers to the process of checking the validity of transactions.

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How to verify if a transaction is signed correctly?

Given an arbitrary signed raw transaction, how can we easily verify if all inputs are correctly signed (assuming all inputs are existent/unspent and the fee is higher than zero)? Bitcoin core's RPC ...
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Basic question about transaction verification

I am fairly new to crypto and had some questions about how transactions are verified by the nodes Would it be correct to say that the full nodes check to see if the sender(Alice’s) signature is valid. ...
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What can I do with “unspent” transactions? Can I transmit them to a chain?

I withdrew some bitcoin from a service's account I maintain. The transaction shows up in my wallet, but it has been marked as "unspent" ever since. What does this mean?
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Why is 'script' used in a transaction instead of the output address?

I see transactions contain script for each output, but this "script" seems to be deterministically derived from the address associated with the output. Why does the bitcoin protocol opt for the use ...
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Unspent bitcoin transaction

So about two weeks ago i sent bitcoin to a friend, and it was confirmed but in the summary it was listed unspent, he claimed not to have received. I was really confused since then, now this morning i ...
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Why is there no such thing as a redirected, forged, or fake transaction?

In the past, we had numerous questions about "fake" or "forged" transactions. Such transactions could supposedly be created even without holding any bitcoins, yet would end up in the mempool or even ...
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If two parties submit a conflicting transaction between each other, how does the network decide which one is correct?

Let's say parties A and B both submit a transaction to the blockchain with a different version of what happened. Party A submits a transaction saying Party B gave him 3 BTC and Party B submits a ...
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How many bitcoin transactions can be verified per second on commodity hardware in 2020?

I am trying to figure out how many Bitcoin transactions could be verified per second. Am I correct that signature verification is more expansive than computing Merkletrees and hashes and constitutes ...
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Given a Bitcoin transaction as JSON data, how can I determine the number of confirmations?

According to blockchain.info, 4,198 confirmations have been received on the following Bitcoin transaction at the time of this writing. Give then following Bitcoin transaction as JSON (ref: transaction ...
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Is it possible to skip verification of blockchain data when using bitcoin core?

Because I need bitcoin core client only for JSON-RPC requests. Will I need pruned initialization or normal initialization of bitcoin core client for successfully running such requests? (I guess client ...
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How do people using thin clients know the correct merkle path of transactions they've sent without knowing the full block?

User A send a transaction to user B. Those transactions are bundled together into a merkle tree. User A and B can both use the transaction plus the merkle root, plus the merkle path to prove the ...
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Transaction validation cost

what relation is between transaction size or a number of input and validation cost? for example, It's o(n) or o(n^2)?
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Bitcoins stuck in memory pool [duplicate]

I sent my 0.1 bitcoin on the 8th of January from an offline wallet (Bitcoin Core), to an online wallet. Still haven't got the btc in my new wallet. The status on the offline wallet says: "unconfirmed, ...
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How do nodes validate that a UTXO in a new transaction is unspent?

Does it check every block in between where the UTXO first appeared and the current time to make sure it didn't get spent then? Or is there some other caching or other method to make the check faster?
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How can a reciever verify that transaction data was not altered by 3rd party?

My scenario: My web server: - Generates private and public, and a wallet address from the public key for a user website account - Server can not connect to the outside (Can not connect to the Bitcoin ...
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At what block height may locktimed transactions get included?

Transactions with outputs whose sequence is smaller than UINT_MAX are interpreted as locked until the timestamp or block height specified in nLockTime is reached. Specifically regarding the block ...
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Get transaction data from full node

Background Information I am building an application that requires the ability to query any bitcoin full node (from a python script using raw tcp sockets) in order to read the OP_Return value listed ...
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Can attackers change transactions during a 51% attack?

If in a 51% attack transactions can be reversed, isn't it possible that the chain with more hash rate also changes transactions (for example if x sent 5 btc to y, they would change it to x sent 500 ...
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How to verify locking and unlocking scripts?

I've selected an arbitrary transaction id and retrieved its associated transaction details using the blockcypher explorer as follows: from blockcypher import get_transaction_details ...
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Verify Bitcoin Transaction

Following the great post [Redeeming a raw transaction step by step example required, I came up with code below but the verification failed. // pubkeyBytes, len: 65 // ...
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Sent BTC from Coinbase, blockchain explorer says Confirmed. Is recipient lying or could something else be the issue?

Sent BTC (approx $500) from Coinbase, Blockchain explorer says Confirmed. Is recipient lying they have not received or could something else be the issue such as his wallet? Recipient says it could be ...
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What stopping miner from altering value in transaction to increase transaction fee?

I'm learning bitcoin through this book "Mastering Bitcoin, 2nd Edition by Andreas M. Antonopoulos". I'm at Chapter 6 "Transactions". Here is my doubt: Example there is node A, received transaction ...
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Not able to Spend 2-2 MultiSig UTXO

I created 2-2 Multisig Account 2NECouPA4UVNMzX1K7kekc4W3VudDhMdFkM from msrFNhKwLu9GrT3hFoizz21xEwJ61xMsym and n1NPFEJHBA8j63B5dgJ3aQcufA8VmrN27U, I tried spending UTXO from this account but got an ...
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How to tell if a transaction is valid?

So I have been reading up on bitcoin and blockchain for awhile now, but I have yet to fully understand it. I understand that bitcoin leverage on DLT, which uses cryptography to verify transaction. ...
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Clarification on the script P2SH, how is executed to Bitcoin core?

This question is a continuation of the my post yesterday. Today I have a question on P2SH execution so, an example of the script should be this OP_0 <A Signature> <B Signature> OP_2 <...
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Bitcoin check if the transaction is valid

When a node receives a new transaction, that node will check if the one broadcasting the transaction has enough coins to initiate it. Bitcoin follows a UTXO model, therefore the node has to check in ...
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How does this simple script use the OP_CHECKSIG opcode?

I have this Script P2PKH <A Signature> <A Public Key> OP_DUP OP_HASH160 <A Public Key Hash> OP_EQUALVERIFY OP_CHECKSIG The bitcoin.org documentation say this The entire ...
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Bitcoin Signature Verification

I am trying to implement the OP_CHECKSIG opcode of Bitcoin and verify whether a signature is valid or not. I have the signature that I recieve from the transaction data and the public key(the hex ...
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Verifying a bitcoin Signature and what is the transaction data that is signed?

Given a bitcoin transaction where it is able to redeem it's UTXO's, how can I verify in Java if the signature is actually a valid signature or not. I was trying to use the Bouncy Castle library where ...
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How does OP_CHECKSIG work

Hi I am learning bitcoin and learning how scripting works and how to use P2PKH. I was wondering how does OP_CHECKSIG work. I want to understand what is the data that the private key signs to create ...
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How to prevent double spending Bitcoins?

If I create a transaction, my node will check my UTXO's and if i have enough BTC to do this transaction it will be mined. So let's say I want to spend 12 BTC to Anna. The System will check if i ...
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What happens to transactions included in extinct or invalid blocks?

I have read that a block contains several transactions. An attacker can forge fake a block. The blockchain is safe because the system will choose and keep the longest chain. So the fake block will ...
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Is verification of a blockchain computationally cheaper than recreating it?

One of the advantages of cryptocurrencies like Bitcoin that is often repeated is how hard it should be to manipulate past transactions. The reason that is often stated is that you would have to re-...
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How exactly do transactions work?

When I search for transaction in bitcoin I am able to find explanations which tell me that there are e.g. two persons A and B and A wants to tranfer a number of bitcoin to B. Imagine A wants to pay 2 ...
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What does “Green address verification” mean in the context of transaction validation?

I am only new to Bitcoin and I would like to know what a "Green address verification" is. I have an Electrum wallet ver 3.3.6 and I think the term is being used in the context of faster transactions ...
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Bitcoin transactions validation process

I have a general understanding of building blocks. But am hoping someone can fill in the details/gaps. Also, can you correct if something is not right? Thanks. Scenario: Bitcoin transactions are ...
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How can I calculate/estimate how quickly a machine can verify transactions on the blockchain?

If I have some machine with particular specs in mind (processor/memory/bandwidth), how can I estimate how quickly that node can download and verify transactions? In a quick search I wasn't able to ...
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Can anyone initiate a Blockchain transaction into the mining pool?

Let's say user A has public key P and corresponding private key P'. Can someone else initiate a transaction for public key P with some wrong private key, let's say P''? Once this goes to the memory ...
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If I set assumevalid=0 after syncing the blockchain will Bitcoin Core go back and validate historical blocks?

I originally synced my node using the Bitcoin Core default assumevalid value. If I set -assumevalid=0 in bitcoin.conf and restart my node, will my node go back and validate historical blocks?
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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? ...
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Besides transaction validation, are there any other uses of the Script language in Bitcoin

Script's stack operations are used to validate signatures and scripts of transaction inputs and outputs. Is Script also used to validate block, network, or any other data? Seem like there are a lot ...
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Checking if a receiver has enough coins

How do miners verify the blockchain transaction history to check if the sender has enough money if the address can be changed at any time?
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How miner makes sure that a transaction he picked up from mempool is actually valid? [duplicate]

I have read and searched enough about the roles and responsibilities of miners here; For example: Does the miner first validate transaction before doing POW or he does not validate at all ? Does a ...
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Why are only specific transaction types accepted into the mempool?

In the Bitcoin Mainnet, only specific transaction types are accepted: Bitcoin uses a scripting language to specify (and satisfy) the encumbrances, thereby allowing a whole host of transaction types....
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Where is sum(vin) > sum(vout) check in Bitcoin Core?

I'm searching the function that validates a transaction according to Protocol rules - "tx" messages especially step 14 sum(vin) > sum(vout). I found this interesting function CheckTransaction(...
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Are transactions with the same ScriptSig a security problem?

For instance while looking at the transaction stack of my address, tracing it to exchanges I use, I came across this: https://www.blockchain.com/btc/tx/...
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Indexing of transactions in the blockchain

Say we have transaction T(1) from many years ago, at block height 125001; then a new transaction T(2), consuming all the outputs from T(1), comes up around block height 568720 (that's Today). There's ...
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Bitcoin checks and balances

When a new block is created, does each block need to be validated? How does it differ from validating transactions? Why miners would waste time validating transactions and blocks when they could ...
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How to generate the digest from a raw bitcoin transaction for verifying signature of specific input?

I'm writing a stand alone process that needs to verify that a known UTXO is part of a new transaction with a valid signature. Inputs [ UTXO, raw transaction, input_number ] How do to I verify the ...

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