By the end of this tutorial, you'll see the first block on the Bitcoin blockchain, created by Satoshi Nakamoto.You'll also see how Bitcoin Core stores blocks on your disk.The first block on the Bitcoin blockchain—block 0—is called the Genesis Block.According to the timestamp in the block header, it was mined on 3 Jan 2009 at 18:15:05 UTC, although (as you'll learn) it contains more proof of work than we'd expect and the mining was only started on January 3rd.Let's take a look at it on the disk of your computer by running the following commands: The cd command changes your directory into the Bitcoin Core block data directory.The hexdump command above displays the first 255 bytes of the file.It should look like this: The output has three columns: The left side is the byte count; it starts at zero and increases by 16 bytes on each line except the last.The middle part is each byte with a space between it and the next byte.

Bytes are represented here in hexadecimal which takes two characters to represent a single byte.When we refer to byte sequences below, we'll use the common prefix of 0x.For example, the first byte in the output is 0xf9.On the right is the ASCII text representation of the hexadecimal data.bitcoin gadget windows 8Bytes that don't map to displayable ASCII are shown as periods.bitcoin friendly banks canadaAlmost none of the data in the blockchain is ASCII, but Nakamoto left us a surprise here (see below for details).bitcoin gibraltarNote the first four bytes, 0xf9beb4d9.bitcoin hex4mThis is called "Bitcoin's magic number", although it isn't really magical.bitcoin billionaire iap cracker

It's just four arbitrary bytes chosen by Nakamoto as a byte sequence otherwise unlikely to appear in a Bitcoin datastream.In the block data files, these bytes identify the start of a new block but they aren't part of the block themselves.These bytes also start each message in the Bitcoin peer-to-peer network protocol to help clients tell when one message ends and another begins.bitcoin holdersYou'll note that the early part of the block contains many zero bytes (0x00).That's because the Genesis Block, unlike every other Bitcoin block, doesn't reference a previous block—it just references a long string of zeroes.This is truly the beginning of the Bitcoin blockchain.Finally, in the ASCII text section, you'll see the message Nakamoto left us: This was part of a special field in the special first transaction of a block, called a coinbase transaction.

In Nakamoto's day, this field allowed miners to include up to 100 bytes of arbitrary data in each block they made.Today, that's been reduced to 97 bytes, but still most miners include a message of some sort in every block they make.Nakamoto's message is especially important.It's the actual headline (although slightly garbled) of a real newspaper, the Financial Times, from the indicated date.This message, which may also express some of Nakamoto's frustration with the pre-Bitcoin financial system, provides extremely strong evidence that Nakamoto couldn't have mined his block earlier than the morning of January 3rd.(Based on the second block on the blockchain, dated January 8th, it's likely that Nakamoto didn't actually finish mining the Genesis Block until a few days later.)Why is this important?We also know that Nakamoto announced that the Bitcoin software was available on the 8th, and that there was another notable user (cryptographer Hal Finney) a few days later, so the proof that he didn't start mining until the 3rd shows that Nakamoto didn't attempt to mine all the early blocks himself in an attempt to create some sort of Ponzi scheme.

If you want to see more of the blockchain, replace the number 255 in the command above with a higher number—but beware, the blockchain is pretty boring for its first few ten thousand blocks.Because the Genesis Block is unlike all other Bitcoin blocks, Nakamoto had to use custom code to mine it.In the next tutorial, we'll help you write your own CPU Bitcoin miner to re-create the exact same block Nakamoto mined as well as learn about what data regular miners include in their block headers.Ubuntu is often recommended as an operating system on which to run Bitcoin Core.Although Bitcoin Core can be installed as a precompiled binary, this method won't work in every case.This guide shows how to compile Bitcoin Core from scratch on a clean Ubuntu 14.04.2 system.The main reason to compile Bitcoin Core yourself is that it ensures you'll always have access to the latest release.For example, the binary Bitcoin Core package for Ubuntu 14.04 32-bit currently fails to install, giving the error message “E: Unable to locate package bitcoin-qt” (the 64-bit version installs without a problem).

Compiling and installing from source eliminates the need to rely on precompiled binaries when updating.A secondary reason to compile from source is that it requires less trust.Although the maintainers of the Bitcoin Core binary package do a fine job, binaries are a few steps removed from raw source code.With each step comes to potential for unexpected issues that can't be easily detected.Source code, in contrast, can be inspected before compilation and installation.Yet another reason to compile from source is to enable custom behavior.For example, the Bitcoin Core GUI and wallet can be disabled if you plan to use the software without those features.The method for installing Bitcoin Core described here requires that you enter text-based commands.The preferred way to do this is through the Terminal application.To access it, click the swirl button in the upper left of the desktop and type “terminal”.Click the leftmost button labeled “Terminal” to launch the application.The Terminal application can alternatively be accessed through the keyboard shortcut Ctrl+Alt+T.

Ubuntu uses a package manager to simplify the downloading and installation of software components.Over time, the configuration of these packages becomes outdated.Ensure that your version of Ubuntu has the latest package information with the following command.Enter your login password when prompted.We'll use Git to access the Bitcoin Core source code.In addition to providing the current version of Bitcoin Core, Git gives ready access to all past and future versions.Next, create a source directory and clone the Bitcoin Core source repository.$ /bitcoin/bitcoin.git After a short time, all files should be ready.To confirm, use the ls command.Bitcoin core requires many software libraries that don't come packaged by default with the Ubuntu distribution.The first one, build-essential, enables software to be compiled from source.Bitcoin Core relies on an old version of the Berkeley Database that is not available as a standard Ubuntu 14.04 package.Although precompiled binaries can be downloaded, in this guide we'll compile from source.