Linked Questions

34 votes
3 answers

Why does Bitcoin use two hash functions (SHA-256 and RIPEMD-160) to create an address?

Why do we use 2 hash functions (both SHA and RIPEMD) to create an address? Why not just use one hash function?
anapaso's user avatar
  • 793
5 votes
1 answer

How does a blockchain store any data?

I read here that since Bitcoin is a networked ledger, it is a good way to back up data. I would like to know two things: How does a blockchain store 'any' data? I would like to know more about a ...
mc9's user avatar
  • 233
4 votes
2 answers

Why would a miner put an OP_RETURN in a coinbase transaction?

I’m looking at this coinbase transaction. I'm confused why there are two outputs and why one of them is labelled with OP_RETURN.
arshbot's user avatar
  • 1,720
9 votes
4 answers

Is there a listing of strange or unusual scripts found in transactions?

I'm studying scripts and am looking for strange or unusual scripts that have appeared in any of the *coin networks..(outside the standard ones listed on this page) Is any one person, or website ...
makerofthings7's user avatar
0 votes
1 answer

Why OP_RETURN should be used instead of raw data?

I've read this great Explanation of what an OP_RETURN transaction looks like and now I have only one question. Imagine that someone want to store some data in Bitcoin's blockchain. Why should he use ...
Sergey Potekhin's user avatar
0 votes
3 answers

Pictures and non-transaction data in block chain

It is well known that non transaction related information has found its way into the block chain. This raises multiple questions: (1) How was it done, and is it still possible (2) If someone where to ...
redcode's user avatar
3 votes
1 answer

Does an OP_RETURN script always need another output within the transaction?

I was reading this: Explanation of what an OP_RETURN transaction looks like and I wondered if the second output "value" : 0.00200000, was at all necessary. Can I just have a OP_RETURN with a 0 output ...
randomshinichi's user avatar
2 votes
1 answer

Upper bound on the Bitcoin transaction size [duplicate]

Assume that I want to store some arbitrary data on the Bitcoin blockchain via a single transaction. Question: Is there any upper bound on the size of data I want to send via a single transaction? -...
user153465's user avatar
2 votes
1 answer

Question regarding the number of bytes in an OP_RETURN transaction

I was reading this very useful explanation of what an OP_RETURN transaction looks like and got tripped up by part of it. "hex" : "6a13636861726c6579206c6f766573206865696469" This first ...
ArrestedDevlopment's user avatar
0 votes
1 answer

Hiding data in OP_RETURN statement?

I'm reading this article, and quote The blockchain transaction’s OP_RETURN data can be decrypted using AES-256 GCM to provide a backup command and control domain name How did someone able to ...
daisy's user avatar
  • 107
0 votes
1 answer

Proving the margin of error of a block timestamp

In the Bitcoin wiki: Block times are accurate only to within an hour or two. is a bit vague. Is it possible to prove that an arbitrary accepted block timestamp is within x seconds of the real-...
Victor's user avatar
  • 121
0 votes
1 answer

Can a client leave its mark on the blockchain?

Would it be possible for a client (eg the core client) to leave its mark in the form of META data on the blockchain or even in the mempool so that we know that this client was used to create or send ...
Doug Peters's user avatar
  • 1,366
0 votes
2 answers

Only My Transaction in a block

I am thinking of broadcasting a Bitcoin transaction with a very important message. The message is so important that I want it to be the only transaction (other than coinbase) in the block. For example ...
transaction0's user avatar
0 votes
1 answer

Additional instructions in TX

Would it be possibile to add additional information in TX? I would like to add time of transaction in it. Would hash of TX change if hostile node would change that time ?
W M's user avatar
  • 1
0 votes
0 answers

Getting Started with a Hello World Node.js App making an API call to

I have been reading around trying to find where/how you can attach a SHA256 or MD5 hash (i.e. a small chunk of data) to a Bitcoin transaction, which led to OP_RETURN, but I have yet to see exactly how ...
Lance's user avatar
  • 221