52 votes
Accepted

Redeeming a raw transaction step by step example required

Step-by-step description: We start creating a new transaction which we hash and sign. Add four-byte version field: 01000000 One-byte varint specifying the number of inputs: 01 32-byte hash of the ...
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  • 6,650
31 votes
Accepted

How is the whitepaper decoded from the blockchain (Tx with ~1000x m of n multisig outputs)

This is a fun little puzzle on the blockchain, basically. First, you need to know a little about pdf's and how they're structured, which you can find here. Second, you'll note from section 3.4.1 that ...
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  • 7,639
27 votes

What is TxIn's sequence?

Note that the accepted answer is outdated. Currently, sequence numbers are mainly used for signaling RBF - replace-by-fee - that allows you to resend a transaction with a higher fee. See https://...
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  • 2,545
17 votes

Anyone know of an API I can get historical price time series for multiple coins

I am developing the ccxt cryptocurrency trading library, check it out on GitHub: https://github.com/kroitor/ccxt It is a library for cryptocurrency trading and e-commerce with support for many ...
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10 votes
Accepted

Where can I find Crypto Coin data?

Acquiring Data You have two options here: Check out one of the data providers online. Quandl offers (mostly) free historical data for a variety of pairs and exchanges. Alternatively, if you have ...
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  • 1,672
9 votes
Accepted

How get raw block data?

There's a boolean parameter to that RPC call that'll return it as a hex string representing the binary contents of the block. If verbosity is 0, returns a string that is serialized, hex-encoded ...
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  • 1,264
8 votes
Accepted

How to store data on the blockchain?

then you have 25 letters in base58, and that's like 17 bytes. 20, actually. So, you have to pay like 0.0001 BTC for the transaction fee, and after that you can add data to that transaction at a ...
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  • 28.7k
8 votes

Anyone know of an API for RSI and other indicators?

I had the same problem, couldn’t seem to find a good API that supported most of the popular indicators, and at the same time covered all the exchanges. So I decided to start up a project for this. So ...
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  • 91
7 votes

Where can I get all historical trades BTC price data?

You might want to try http://www.cryptodatasets.com/ It has free raw data and sampled data from Bitfinex and HitBtc (currently). P.S. it's my website
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  • 151
7 votes
Accepted

Raw Block data in Hexadecimals

What kind of API do you want? Do you mean API with your local Bitcoin Core or do you need web-API? Have a look to http://webbtc.com/block/...
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  • 6,650
7 votes
Accepted

Anyone know of an API I can get historical price time series for multiple coins

Found the data on crypto compare const endpoint = 'https://min-api.cryptocompare.com/data/histoday?aggregate=1&e=CCCAGG&extraParams=CryptoCompare&fsym='+ ticker.toUpperCase() +'&limit=...
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6 votes

How is the whitepaper decoded from the blockchain (Tx with ~1000x m of n multisig outputs)

This is a bash command that can also give you the file: bitcoin-cli getrawtransaction 54e48e5f5c656b26c3bca14a8c95aa583d07ebe84dde3b7dd4a78f4e4186e713 0 ...
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  • 11.4k
6 votes
Accepted

How much out of order are the blocks stored in the blk*.dat files?

1024. /** Size of the "block download window": how far ahead of our current height do we fetch? * Larger windows tolerate larger download speed differences between peer, but increase the potential ...
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  • 28.7k
6 votes
Accepted

UXTO DB structure

Each entry in the new 0.15 format is defined as outpoint:coin, and has the following structure: Outpoint is formed by: key | tx_hash | index. Where the key corresponds to b'C', or 43 in hex. The ...
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  • 2,712
5 votes

How to store data on the blockchain?

It's been done. It's lame. It's spam. You're incurring cost on the whole network for perpetuity (and no, the fee doesn't pay for that). If you really can't stop yourself look at OP_RETURN as that's ...
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  • 6,208
5 votes

Anyone know of an API I can get historical price time series for multiple coins

http://www.cryptocoincharts.info Advance API to more than 100 exchanges: cryptocurrency pricing, OHLC and volume data from multiple exchanges. BTC38, BTCC, BTER, Bit2C, Bitfinex, Bitstamp, Bittrex, ...
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  • 59
5 votes

Is it possible to download all blockchain raw data?

Any (full) Bitcoin client will download the entire blockchain. It's stored in files on disk which you can look at after it's been downloaded. The current blockchain size is 115 GB of raw data (the ...
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  • 3,421
5 votes
Accepted

Are there any blockchain explorers that provide raw Tx data and block headers?

You can get this info from blockchain.info, by simply adding ?format=hexto the end of the relevant URL. For example, here is a recent block (height 509,244): https://blockchain.info/block/...
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  • 17.4k
4 votes

How to delete an element of an array in an Ethereum contract?

Refer to the documentation: delete myArray[arrayIndex];
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4 votes
Accepted

Are there any Python modules that decode raw transaction data?

Yes, Pybitcointools (or this fork which has BIP39, file embedding and mk_opreturn) can do this. Install either version of pybitcointools using setup.py install, as usual. Then, with a raw hex ...
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4 votes

Redeeming a raw transaction step by step example required

This is an excellent answer by amaclin and Wizard of Ozzie. I'd just like to add some more detail for the Wizard of Ozzie's transaction at blockchain.info. The correct input to the signature process ...
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  • 141
4 votes

How to store data on the blockchain?

You could use the OP_RETURN operation in your pubkey script. It gives you 80 bytes of free data (I think it is upgraded from 40 bytes recently you could check). If you are a developer you could ...
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  • 1,101
4 votes

Anyone know of an API for RSI and other indicators?

You can calculate it yourself. Use an API to get the gains and losses over an period of 14 points and put it into the formula described here: http://stockcharts.com/school/doku.php?id=chart_school:...
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  • 141
4 votes
Accepted

What are the hashes in Unspent outputs?

tx_hash and tx_hash_big_endian are the transaction id of the transaction that this output originated from in little endian and big endian (reversed). tx_output_n is the number of the output in the ...
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  • 3,225
4 votes
Accepted

Which blk*.dat file contains a particular block?

Is there a way to find out which blk*.dat file contains a particular block? We can't tell you which of your *.dat files contains block 478558 because there is no requirement that different nodes ...
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4 votes

Is there evidence for lack of stale blocks?

The average block propagation time actually used to be more than 15 seconds before 2016, see the "Block Propagation Delay History" Graph at the KIT statistics website. However, block latency ...
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  • 421
4 votes
Accepted

What is the different between CompactSize and VarInt encoding?

There are two distinct variable-length integer encodings implemented in Bitcoin Core's serialization framework: The encoding used in the P2P protocol for the lengths of vectors (number of ...
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4 votes
Accepted

How much bitcoin in Canada?

How much bitcoin in Canada? That's a very interesting question: None of it. It isn't always possible to say that an address is based in Canada. Some Canadians might use wallets on mobile phones. If ...
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3 votes

How to store data on the blockchain?

Bitcoin is for transactions, not storage. A bitcoin-derived system like Ethereum can be used to implement this. StorJ or FileCoin are special blockchain-like systems just for storage.
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  • 171
3 votes

Non standard Tx with obscure OP codes: examples

I found an INCREDIBLY detailed spreadsheet documenting every single "weird" Tx up until March 2014. It's available at John Ratcliff's Code Suppository in his "Transaction Input Signatures in the ...
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