thanks for the response. Googling for the above file names took me to a reddit link mentioning an article "Bitcoin: 285 bytes that changed the world", which was published 4 years ago, and is no longer available. However, I found it in the internet archive and it contains exactly what I was looking for.

For those interested https://web.archive.org/web/20140213190023/http://james.lab6.com/2012/01/12/bitcoin-285-bytes-that-changed-the-world/

you are correct, this is what i meant by that statement.

However, on second thoughts, I realize that only filesystems such as FAT16 and FAT32 will not be able to handle that file size. (FAT16 cannot even have a partition larger than 2GB) Generally, even someone still running Windows XP (definitely not recommended) can be expected to have it installed on a NTFS drive.

Thanks, could you please guide me to some place where I can find some information regarding the content and structure of these files, how they are numbered, the default locations they are saved in (for Windows, Linux etc.) ?

please excuse me for the noob like question. But I am asking since I use Electrum and do not run bitcoin-core.

In what form does the blockchain exist on full nodes, is it as a single file or a collection of files ? If more than 1 file are they numbered in any way ?  I am almost certain it is not a single 60+ GB file, since all OSes may not support that.

Does the actual blockchain contain extra data besides the actual blocks (meta data for indexing etc.)?

THIS is exactly what I wanted. In fact it is more than what I wanted. Thanks a lot.

To all those who posted above. Thanks for your replies. But I will only be considering bitgen, since the features I need are present in it.

I would like to share my (negative) experiences at cryptotalk.net I leave it to the readers to decide as they deem fit.

I signed up at the said forum about 5 weeks ago using the id cyberguy, posted a little over 25 posts and got my first payment promptly after requesting it. I happily started posting again, but when I had posted about 20 more posts, suddenly found my membership deleted along with all my posts. All my posts were original content based on facts I had learnt from various sources, but I never did any copy pasting of articles. To get an idea of the type of stuff I posted please have a look at this thread started by me. This is when I posted here requesting the admin to clarify matters. I know such posts will not interest everyone, but there was nothing in the forum rules against it, so I carried on with a variety of topics that came to my mind.

After my id got deleted I posted here seeking clarification from the admin and got this lame reply. I maintained silence and did not try to defend myself in spite of the admin accusing me of making copy paste posts, because I had managed to register again using the same id and had started to post. I was prepared to overlook what had happened. Once again I managed to complete 25 posts, following which I requested a payment. The payment was not as prompt as before, but I received it, and then started posting again. Last Monday, I had completed another set of 25 posts and made a payment request. On Wednesday morning I found once again that my id had been deleted again with all my posts.

I do not understand what sort of  forum the admin wishes to build. He accused me of copy pasting merely due to the length of my posts without any further investigation. If someone takes the time to carefully read the posts of some members who have posted over 100 posts it will be quite evident how copy pasting has been done by some of them.

The remnants of a thread started by me can be found here

Below I am posting the 3 posts which I had posted on this thread which have now been deleted (these are from local copies i had saved after posting) You will observe "mocacinno" has quoted my last post. I am only doing this so that readers can be convinced that the information posted by me, previously is true, since the admin may make an appearance and start accusing me again.

post 1----------------------------------------------------------------------------------------------------------------------
The API at https://blockchain.info can be used to generate image files with QR codes of a required resolution. Open up any GUI web browser, type
in the address bar and press enter. This will open a new web page containing an image of the requested resolution for the QR code that corresponds to your data. The title bar of the browser will indicate the data and the resolution used. If the size parameter is not used, as in
The generated image has a default size of 350x350 pixels. The QR code is presented as a PNG image, and can be saved to the disk by right-clicking on the image and selecting the "save image as" or similar option available with most browsers.

On a UNIX like system (such as Linux), you can generate the PNG image on the command line, without using any browser, if you have "curl", as follows

This will save the image to filename.png which can be opened using any image viewer.

To illustrate an example, if you need the QR code for the bitcoin address 19HHqF5C3MTobxwqojWi1iUYzFiQFtHZ7X as a 256x256 pixel image, use
as URL. If you need to generate the image file on the commandline, use
at the linux console.

Theoritically, this can be used even to generate QR codes for a private key, but this should never be done, since the moment a private key is transmitted over a network (the internet in this case), the associated bitcoin address will have to be considred as compromised.
end of post 1----------------------------------------------------------------------------------------------------------------------

post 2----------------------------------------------------------------------------------------------------------------------
qrencode and zbarimg are two commandline utilities that can be used to encode (generate) and decode QR codes respectively. They can be installed, along with all required dependencies, on any debian based Linux distribution such as Debian, Ubuntu, Trisquel etc. by running
as super user (root) from a Linux console. These can be used offline and are hence safe to use even for encoding and decoding private keys.

qrencode is used to generate an image file from a given string, which may be a bitcoin address, private key or anything else. The default output is a PNG file, but there are a large number of options that can be used to change the default settings, which can be seen by running

zbarimg which is included in the zbar-tools package can be used to decode an image file containing a QR code. Its basic usage is

This will print the text encoded in the QR code to the screen.

This can be useful in a situation where a QR code needs to be scanned but a webcam or a smartphone is not available. A photo can be taken of the QR code using an ordinary camera phone or digital camera, uploaded to the PC via USB or bluetooth and decoded using zbarimg. While this is too cumbersome for ordinary use, it could be handy in an emergency.

zbarcam which is also included with the zbar-tools package can be used to scan and decode a QR code when a web cam is available.
end of post 2----------------------------------------------------------------------------------------------------------------------

post 3----------------------------------------------------------------------------------------------------------------------
https://zxing.org is a website where QR codes and many other types of bar codes can be decoded online. You can either upload an image file or submit the URL of an online image containing the code. This can be quite handy when shopping online, and you need to obtain a bitcoin address from a QR code quickly. Another significant feature of this website is that it does not require java script to function. In fact it can be used even with a text only browser such as lynx or elinks. (for those who are unaware - yes, such browsers exist. read more here)

For more information regarding QR codes visit http://www.qrcode.com/en/about/index.html
end of post 3----------------------------------------------------------------------------------------------------------------------

All I can say is be prepared for disappointments if you intend signing up at cryptotalk.net, especially if you intend contributing posts with substance. You are better off trying to earn by blogging.

thanks.

two different private keys will never share the same public key. What is implied by the above quote is that many different private keys may share the same public key hash, which is not the same thing as the public key. I am not a cryptography expert, but I am 99% sure the answer to your question is no, if you actually meant public key hash.

try using bitcoin-tx that is included with bitcoin-core

you'll have to do all the calculations before you construct the tx

The following iswhat I learnt by trial and error, I couldn't find any documentation on this


The above can be used for a simple transaction which takes a single input and has a single output. The following values should be used as arguments.

TX_ID:INDEX - transaction hash and index of input

VALUE:ADDRESS - amount of BTC to be sent along with bitcoin address

PUBLIC_KEY_HASH - public key hash of bitcoin address from which BTC is being spent

PRIVATE_KEY - private key of bitcoin address from which BTC is being spent

When multiple inputs received by the same address need to be specified, there should be a "in=TX_ID:INDEX" argument that corresponds to each input. It has to be specified again under the prevtxs array. i.e. multiple {"txid":"TX_ID","vout":INDEX,"scriptPubKey":"76a914PUBLIC_KEY_HASH88ac"} arguments corresponding to each input seperated by commas within the square brackets. Multiple outputs can be specified by including "outaddr=VALUE:ADDRESS" corresponding to each output.

The output produced is the raw transaction as a string of hexadecimal characters.

thanks, will give it a try

I need something that can run on a 32-bit machine with low memory requirements

is there any command line utility that can be used to do the secp256k1 calculation on a given hexadecimal number (private key) and print the result (public key) to stdout in compressed and/or uncompressed form. can this be done using openssl ?

I request editor status

wiki username: Cyberguy

Latest information regarding http://cryptotalk.net/, where members are paid for posting

Currently, there are 321 registered members.  The admin has restored my account, which was removed a few days ago due to a complaint. A total of 14 payouts have been done so far as shown here. 3 members (including myself) have received two payments. 8 members have received their first payments.

For anybody who is getting started with bitcoin and wants to earn some satoshis, it would be a good idea to join the forum and start posting. (subject to the rules and conditions of the forum as given here) IMHO this is a much better way to acquire a few satoshi than wasting time at faucets.

I am using Electrum 2.6.4 on Linux, and when I attempted to make the fee zero, received a message saying this is not allowed. I do not know when this was introduced.

you can use bitcoin-tx that comes with bitcoin-core to create any custom transaction including one with zero fees. But I don't think the network will accept such transactions. Once I tried pushing such a tx (which contained valid data) using https://blockchain.info/pushtx and it was rejected. While Electrum allows adjusting fees to custom values, it does not allow creating zero fee transactions.

Can we consider the paper wallet as compromised even after taking all the precautions mentioned in my description.
(1) Using a dedicated machine with no writable media
(2) Using TAILS - clean Linux OS with no malware
(3) Not using the persistance feature of TAILS
(4) No connection to any LAN

The private key will be written to the RAM, since the home drive of the user will exist in RAM only, by using a password we ensure that what gets written to RAM is the encrypted pasword.

It is generally recommended to use a paper wallet like a piggy bank. i.e. you may put funds as many times as you want, but when you spend, withdraw all the funds in the paper wallet and transfer them to another bitcoin address you own. As I understand, this is because importing the private key of the paper wallet introduces a security hole, where the key may be retained on the device used for withdrawing funds and anybody who gains access to it will be in a position to steal any funds at the corresponding address.

If the following procedure is adopted, will it be safe to spend from the paper wallet address multiple times, just like spending from any ordinary address stored in a regular desktop wallet ? I would like to know the views of others.

Procedure
(1) Prepare a paper wallet in a secure way and receive BTC to the address given on it
(2) Have a dedicated PC to use for spending. This can be any old PC with at least 2GB of RAM and capable of booting from a CD or DVD. Ensure that all internal storage media are disconnected from the motherboard except a single CD/DVD drive. Do not connect any external peripherals except the mouse, keyboard, monitor and router/modem
(3) Download and burn to a CD/DVD the latest version of TAILS
(4) Boot the machine with the TAILS live CD and connect to the internet. Use a direct connection to the internet and do not connect via a LAN.
(5) Start Electrum (it comes with TAILS) and use the recovery option with the private key of the paper wallet to create a new wallet, enter a password and confirm when prompted and allow synchronization. This will only have the paper wallet address. (The wallet data will be saved only in the RAM since this is a live session. For added security we use a password so that even this is in encrypted form)
(6) Do any transactions you want and shutdown the computer. Do not save any data for future sessions using another media such as a USB drive. (Electrum will take care that change is returned to your own address, but always check before signing and broadcating)
(7) Repeat the above procedure whenever you need to spend from your paper wallet

The only inconvenience that I notice is that the private key will have to be typed every time the computing is started up. Are there any security risks in the above procedure ?

the first two or three posts have to be approved by the admin. This appears to take up to two days sometime.

hello, i am interested in this. you can see this post for a sample of my writing