Questions tagged [script]
This tag should be used for questions regarding Bitcoin transaction scripts or scripting languages used in transactions of altcoins such as Solidity. Scripts are a set of instructions on how to complete a transaction.
427
questions
2
votes
1answer
74 views
How to calculate variable length fields?
Some parts of bitcoin tx Ex: Script are of variable length var_int. Can someone explain how to calculate its value from that var_int table.
Ex: In the below tx, the bolded part is script-length. its ...
0
votes
2answers
170 views
How is a transaction formated/signed?
Every transaction takes unspent outputs as inputs and creates new outputs. The creator of the transaction uses his private key to sign the transaction and nodes validate that transaction by using the ...
1
vote
0answers
107 views
What does this elaborate output script mean? [duplicate]
Bitcoin transaction a214a2daf91691afdd491fd00d894eb3301e35bc18b5554b14e12843037e954c has an interesting output script:
PUSHDATA(33)[...
4
votes
2answers
586 views
What does this transaction script mean?
I was looking for scripts on the blockchain to test my program, and I encountered a weird scriptPubKey in this tx that I couldn't understand.
The opcodes are
pk1 = ...
0
votes
1answer
134 views
How would one go about acquiring the HashofThingtoSign from this old transaction?
How would one go about acquiring the HashofThingToSign that is used in the "Signature Generation" equation for this example transaction such that it could easily also be applied to any other given pre-...
1
vote
1answer
760 views
Single signature P2SH redeem script
How would one go about creating a single signature P2SH transaction? (Analogous to a "2 of 3 multisig P2SH" but instead I'm asking about a "1 of 1".) Would one wrap a standard P2PKH scriptPubKey ...
1
vote
0answers
61 views
what are ScriptSig? [duplicate]
I was studying bitcoin script, and upon watching this transaction in blockexplorer i was confused , what exactly is ScriptSig and scriptPubKey is of reciever?
According to what I know, the receiver ...
1
vote
2answers
141 views
Can bitcoin script look at the output?
I was wondering if it possible for a bitcoin script check part of the output of the transaction.
Lets say, I want to check that the transaction is splited equaly between 3 outputs, I dont care which.
1
vote
1answer
64 views
anyonecanspend final condition of a script can be spotted just by looking at the script hash, without the redeem data?
Consider the following scenario.
Alice, Carol and Bob create and fund a script with the following rules:
if now, alice pubkey, bob pubkey
else
if now+500 blocks, bob pubkey, carol pubkey
else
if now+...
0
votes
1answer
64 views
hash locked multisig, can one cosigner sign without the pre-image?
Consider Alice and Bob created the following native segwit script:
hash SHA256 defined as H | Alice PubKey | Bob Pubkey
Only Bob has the pre-image (plain text that hashes [sha256] to H). Can Alice ...
4
votes
3answers
793 views
Why does Bitcoin uses a Script language?
From what I heard is that Bitcoin use Script to verify transactions (I'm probably wrong).
Wouldn't be sufficient just signing the transaction with the private key and append the signature to the ...
2
votes
1answer
516 views
what is the difference between OP_CHECKMULTISIG and OP_CHECKMULTISIGVERIFY
I would like to learn the difference, explained as simple as possible, between OP_CHECKMULTISIG / OP_CHECKMULTISIGVERIFY and OP_CHECKSIG / OP_CHECKSIGVERIFY. The only explanation I found is: Same as ...
5
votes
1answer
585 views
How are sigops calculated?
How are sigops calculated on a transaction? For example in the (randomly selected) following transaction:
https://btc.com/bc9384919ad5d08b2c66e31f29e7c63572c398a87631c03a4ce9e94ff1cbe62f
It says ...
3
votes
2answers
90 views
Is it possible to make an output only spendable to a specific address?
Basically, the entire question fits into the title. Does the Bitcoin scripting language allow for a transaction output to only be spendable to a specific address? Is it possible to forbid all other ...
0
votes
0answers
473 views
Error: mandatory-script-verify-flag-failed
I have created a raw transaction from myElectrum wallet, but when I try to broadcast it I get this error:
mandatory-script-verify-flag-failed
Why is this happening?
The transaction is below:
...
1
vote
1answer
446 views
Why does the Genesis block coinbase input script push bits and the value 0x04 before the famous “Chancellor” message?
According to the Wiki, the input script of the Genesis block consists of these bytes:
...
17
votes
3answers
2k views
Will general non-standard transactions ever be allowed?
To the best of my knowledge, currently "Satoshi" client relays and most pools accept only standard (transfer or generation) transactions. Besides, community is working on M-of-N transaction type. ...
0
votes
2answers
404 views
Creating an OP_CSV transaction with bitcoinjs
I'm working on a tool for timelocked contract generation. My redeem script looks like so:
OP_HASH160 <revocationHash> OP_EQUAL
OP_IF
<bobPubKey>
OP_ELSE
<timeDelay> ...
0
votes
1answer
358 views
How secure is bitcoin private key generated by this script? [closed]
I found this python script on github.
It generates a pair of bitcoin private key and address.
I know the private key may be vulnerable if it is created insecurely.
I don't have much knowledge ...
6
votes
2answers
602 views
Which bitcoin script forms should be detected when tracking wallet balance?
I am implementing a library for tracking wallet balance of given bitcoin addresses.
How should the transaction output script be parsed to find if the output belongs to the given address?
Is it dirty ...
14
votes
3answers
4k views
The Bitcoin scripting system is purposefully not Turing-complete - why?
Can somebody explain to me why the Bitcoin scripting system is purposefully not Turing-complete? To make malicious programs difficult to develop (I guess)? Or because it was difficult to make it ...
1
vote
1answer
135 views
Why does this script return an error ?
I'm trying to understand how Script validates transactions.
I have taken this transaction as an example 55e5bbdba33050bbe6584e896b4a20575cf3fe3f29114467f17f67f6b172eb73
When showing the scripts, we ...
2
votes
2answers
173 views
Mastering Bitcoin: Advanced Scripting Question
At the end of Mastering Bitcoin Chapter 7. https://github.com/bitcoinbook/bitcoinbook/blob/second_edition/ch07.asciidoc#complex-script-example
They ask this question in regards to the script:
How do ...
15
votes
2answers
3k views
How to create a transaction with a custom script?
Is there a step-by-step tutorial or any documentation covering how to create a transaction that is not a standard OP_DUP OP_HASH160 <pubKeyHash> OP_EQUALVERIFY OP_CHECKSIG?
It seems very odd ...
1
vote
1answer
121 views
Where to find the sighash type?
Where can I find the sighash type specified in a script?
Is it included in the scriptsig?
1
vote
1answer
602 views
How do I print unspent transaction outputs of an address using pybitcointools
I am a beginner looking to write a simple program that takes an input (address) and prints the unspent amount in it.
I copied some code from chapter 4 of Mastering Bitcoin to generate a random ...
2
votes
1answer
661 views
Multiple input/output transactions using golang btcd
I am using golang's btcd as a basis for creating some server-side tools for handling transactions. I found a good example for creating a basic one-input-one-output transaction to get me started on the ...
0
votes
1answer
2k views
Signature verification in python
When trying to implement OP_CHECKSIG, I am unable to figure out how to do the actual signature verification in python (python3)
I obtained the signature, public key, and hashed message digest of a ...
8
votes
2answers
2k views
Different error messages under “Mandatory script verify flag failed.”
I've been playing with raw transactions and signed transaction and I've noticed that the error "Mandatory script verify flag failed" comes in two variations.
script failed on OP_EQUALVERIFY OP
Script ...
0
votes
3answers
2k views
What is wrong with my ScriptSig? I get 64: scriptsig-not-pushonly
I currently try to create and sign transaction from scratch. I made it to construct and sign a transaction. If I verify it manually it looks good but using a "proper" wallet my transaction is refused:
...
1
vote
1answer
661 views
How to restore redeem script from a spent transaction?
What is the procedure to restore redeem script of P2SH address from a transaction sent from that address? The script is stored on the blockchain in the tx data, the question is how to extract it?
2
votes
2answers
238 views
Why are there so many opcodes in Bitcoin Script, but they are not usable
In my understanding, miners wont accept non standard scripts. Then why are there several opcodes which cannot be used in custom scripts because they are nonstandard?
1
vote
1answer
210 views
OP_ADD operation in bitcoin script for integers greater than 128 in java
I want to execute a simple series of instructions to implement a bitcoin script in java using bitcoinj API. All I am looking for is performing arithmetic operations for negative integers or integers ...
1
vote
2answers
1k views
Convert plaintext script into hex-encoded script in python
I'm creating a program (for an altcoin I'm developing) that should make it easy to create OP_RETURN transactions. Currently I'm having some trouble with actually creating the script pythonically (I ...
1
vote
1answer
529 views
Bitcoin core multisig signing order
I have a technical question regarding the signrawtransaction function in Bitcoin core when signing a partially-signed transaction.
I have tested different scenarios and signrawtransaction will always ...
2
votes
1answer
126 views
How can blockchain.info show the output address of a transaction when the output address has never been used in any other transaction?
I've stumbled across a transition on blockchain.info where the output address was displayed even though the output address had never been used in any other transaction.
How can blockchain.info know ...
0
votes
1answer
71 views
Why there are no OP_CODEs for querying the blockchain and retrieving data to the stack?
Blockchain data is immutable, so once valid a transaction will always be valid and full nodes can verify it.
5
votes
1answer
229 views
ScriptSig content during signature (quadratic hashing)
As far as I know, the quadratic hashing problem came from the fact that every time a transaction is verified (or signed), the "unsigned transaction" that is hashed and verified changes depending on ...
9
votes
1answer
1k views
How is a “standard” Bitcoin transaction defined?
This is useful in Andreas Antonopoulos' book, Mastering Bitcoin:
https://github.com/bitcoinbook/bitcoinbook/blob/7c552ea5cfbc19448635b36407761b377ff5cbe9/ch05.asciidoc#standard-transactions
"In the ...
1
vote
1answer
994 views
Spending transaction with custom output
I've recently entered the bitcoin arena, and bitcoinj was my tool choice. Experimenting on regression test mode, I was able to create the following custom transaction. It has a modified locking script ...
0
votes
1answer
429 views
Why is using a simple SHA1 in a scriptPubKey to emulate a “password” a security problem?
I'm independently working my way through an excellent online course on bitcoin, made available from Stanford. (https://crypto.stanford.edu/cs251).
One of the problems in the homework challenges the ...
3
votes
1answer
955 views
Missing public key in transaction input
I'm in the process of understanding scriptSigs of transaction inputs and encountered some transactions with inputs that seem to be missing a public key.
This is what I expect to see as a scriptSig. A ...
10
votes
2answers
2k views
What is OP_CODESEPARATOR used for?
Looking at the bitcoin source (https://github.com/bitcoin/bitcoin/blob/v0.9.3/src/script.cpp#L843-L847, specifically), I ran into the the use of the OP_CODESEPARATOR. Am I right in interpreting this ...
2
votes
1answer
655 views
How to tell which part of the previous tx I need to make the hash to sign for an old given tx?
I have recently been taught (here) how to create the hash to sign for a given "input script" for an existing transaction. I then sought to test my abilities and sought out a difficult transaction to ...
2
votes
3answers
3k views
What are the parts of a Bitcoin Transaction “Input” script?
All the terminologies I find seem rather confusing about what explains what and they usually miss a few steps.
Example: Transaction 82d62d5f4e69ae8338c39b7ae2e1d33db59bdf62c869ded7344adc936bab8653
...
1
vote
1answer
875 views
Why are Virtual Machines used in Ethereum?
I'm wondering why the Ethereum Virtual Machine (EVM) is used?
What if they didn't use it?
Why don't we have them in Bitcoin?
1
vote
3answers
593 views
OP_HASH160 and number of bytes of public key
When creating a raw transaction, why after the OP_HASH160 the number of bytes of the hashed public key should be included if it's always 20 bytes (that's what RIPEMD160 throws)?
Does this happen with ...
1
vote
1answer
121 views
Create an arbitrary script with two locktimes and p2sh
Alice, Bob and Carol create a p2sh address that initially requires 3/3 signatures. After some time (lock1 using OP_CHECKLOCKTIMEVERIFY) only Alice and Carol can spend and Bob is permanently forgot. ...
0
votes
1answer
153 views
How many IF/ELSE/ENDIF can be used in a script?
Besides the 520 bytes consensus rule limit, is there a limit on how many of each OP_IF, OP_ELSE and OP_ENDIF can be used in a single script?
For example, a company that has 3 people in its purchase ...
0
votes
1answer
49 views
Is there a limit in bits for the data hashed in hash-locked script?
What is the limit in bits for the plain-text data of a secret (the data that it is actually hashed and used in a script) in a hash locked contract?
