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 transaction from which we want to redeem an output (reverse order): be66e10da854e7aea9338c1f91cd489768d1d6d7189f586d7a3613f2a24d5396
Four-byte field denoting the ...
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 all pdf's start with this string:
In hex, that is 255044462d. And indeed that is in the very first output in the very first bare multisig pubkey:
Note that the accepted answer is outdated.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://bitcoincore.org/en/faq/optin_rbf/ , https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki
I am developing the ccxt cryptocurrency trading library, check it out on GitHub:
It is a library for cryptocurrency trading and e-commerce with support for many bitcoin/ether/altcoin exchange markets and merchant APIs.
With it you can access market data and trade bitcoin, ether and altcoins with more than 70 (!!!) ...
This guy wanted to do the same thing. You can find a solution there.
get a Linux Box/VM with >=8GB RAM
run "./parser allBalances -w 250000 >allBalances.txt"
the parser run take around 2 minutes on my vSphere VM (2x3Ghz Xeon, 16GB of RAM)
now you have a list of the top 250.000 adresses ...
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 bucks to spare, Coinigy offers high-quality data sets on a per-month pricing model.
Roll your own data crawler, using a programming language of your choice and the ...
then you have 25 letters in base58, and that's like 17 bytes.
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 price of 17bytes per 1 satoshi, by sending satoshis to many addresses that contains the whole data. Imagine if we could store data there forever,.. and ...
The number of confirmations is (height of most recent block - height of the block containing the transaction + 1). The contents of the specific block containing the transaction are fixed, while the number of confirmations keeps increasing, so the number of confirmations cannot be in the raw block data.
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=365&tryConversion=false&tsym=' + currency.toUpperCase();
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 data for block 'hash'
getblock 'hash' 0 should return what you want.
You can get complete and up-to-date price history here:
You can also get subsets of the data.
For details see: http://bitcoincharts.com/about/markets-api/
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/000000000000000001f942eb4bfa0aeccb6a14c268f4c72d5fff17270da771b9 (this is an example)
It is possible to download block as [json] / [hex] / [binary] there if you know the hash of the block
block in ...
/** 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
* degree of disordering of blocks on disk (which make reindexing and in the future perhaps pruning
* harder). We'll probably want to make this a per-peer ...
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 transaction hash in encoded in Little endian, and the index
is a base128 varint. The corresponding Bitcoin Core source code can be found here.
On the other ...
SX is a set of modular Bitcoin commandline utilities that admin types can engage with Bitcoin functionality without having to write code.
Using the Mycelium mobile app has to be the easiest method to spend funds from a paper wallet. From the app, select ...
Electrum has a gui form for just that. Also I think brainwallet.org has a web form that works offline and runs off github source directly so you can verify privacy concerns.
Edit: also see:
As referenced in Transaction signature generation
Two new command-line or bitcoin.conf file commands have been added in the 0.8 release that allow for historical transactions to be accessible by recreating the old index:
txindex : maintains an extra index of old, spent transaction ids so they will be found
by the getrawtransaction JSON-RPC method.
reindex : rebuild block and transaction indices ...
I created a fork of blockparser with a 'csvdump' command that will generate a details dump of the blockchain in CSV format. There are also some support scripts in that repository for creation, population and periodic update of a PostgreSQL database.
Be aware that the resultant database is pretty large; you might want to consider PostgreSQL over SQLite for ...
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 at least a much more network friendly way of doing it.
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 size on disk will be a bit larger because of indexes created by the client).
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):
And here is the raw data for that block, in hex:
Also, there was a Bitcoin Time Series spreadsheet. Scroll to the bottom to see the data sources.
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 transaction, rawtx, simply use txo = deserialize(rawtx). rawtx can be either a signed or unsigned hex transaction. The returned txo is deserialized as a dict object. ...
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 referenced transaction, i.e if a transaction has 5 outputs and you need to refer to the 5th you use a tx_output_n = 5.
tx_index I believe is an internal unique ...