Are blocks sent only after finding nonce?


This effectively already happens on several levels, though without direct miner interaction. Both Bitcoin Core and the Bitcoin Relay Network have their own implementation of forward preparation for the validation of blocks with the intent of speeding up block propagation as much as possible. One focused on validation latency, one on bandwidth and latency.

Bitcoin Core has a validation cache of transactions it sees unconfirmed on the network, this allows the most expensive operations (executing the script, and validating signatures) to happen long before they are included in any block. Very often a node which has been active on the network for even a few minutes has already validated a large portion of any new blocks that arrive. When a new block is seen the uncached transactions are validated, inputs are checked, and the block is connected without having to do extensive, expensive validation of the contents.

The Bitcoin Relay Network takes this concept even further,...

0 0

Basically, there is no such thing as a "correct" nonce, only a set of possible "correct" blocks which can use any nonce they wish to obtain an acceptable hash. So the nonce is just "some arbitrary number". But in order to understand how nonces work, you first have to understand the hashing process by which blocks are produced.

Cryptographic hashes are a mathematical way of turning any set of data into a random number, called a hash. The hashing process is designed so that it's easy to calculate the hash of some data but nearly impossible to find data which will fit a specific hash, having even a slightly different set of data will produce a totally different hash, and so that the only way to find a hash with a particular property (say, being below a certain number) is to calculate lots of them until you get lucky.

In the Bitcoin network, only blocks with certain hashes get accepted and included in the official list. The criteria for which blocks "count" is that their...

0 0

There are many descriptions of what mining is, but none of them describe it exactly. From what I gather:

Mining means finding a nonce c such that for some information s the hash value h(s||c) begins with a certain number of zeros (h is sha-256, || concatenation).

The "information" is given here. The nonce is an integer that is incremented in the mining process. But it seems that it's not s||c that is hashed, but rather there is some double hashing going on, but of what, h(s)||c, h(s||c), h(s)||h(c)? I can't deduce it from the Python code in the previous link (NB: I'm code illiterate).

Also the nonce isn't just initialized at zero and then incremented until there's success:

To avoid risking wasting work in this way, there needs to be a random starting point, and so the work becomes to find H(s,x,c)/2^(n-k) = 0 where x is random (eg 128-bits to make it statistically infeasible for two users to maliciously or accidentally start at the same point), and c...

0 0

There's a difference between what is called a "golden nonce" in the context of the source and a valid block header hash.

To reduce payout variance, miners group into pools and share their income proportionally to their hashpower.

To determine each miner's hashpower, pools use a share system: when you are mining and find a block header of high difficulty (with lots of heading zeroes) but not high enough to be above the current target, you send it to the pool. These difficult-but-not-enough headers are called "shares".

Since finding them is way more frequent than blocks (miners often send several of them per second), no matter how small your hashpower is, it will still be taken in account at payout time even if you're unlucky. The more shares you send, the more hashpower you have, the bigger the share of the pool's income you will get.

They are not broadcast to the bitcoin network, since they would be immediately rejected there and are of no value to...

0 0

When it's used as it's intended to, the nonce usually begins at a certain point and increments from there. This can restart every second, since there is a second-specific timestamp in the block, but modern ASICs can do far more than 2^32 hashes per second, so it seems reasonable that nonces should be distributed fairly evenly.

may a miner force a mined block to have a specific nonce? (if his hashrate allows him to)

Yes. He'd do this by fixing his block header's nonce and changing transactions instead (the coinbase transaction, a.k.a. block reward, is a perfect place for this); by changing any transaction, the Merkle root in the block header will change.

The usual mining loop only takes two SHA256 hashes per attempt. If you only include the coinbase transaction in your block, this will add (at least; I'm unsure if it'd have to fill out 1 to be an even number, as it does for 3) two SHA256 hashes per attempt, meaning you'd be (at least) twice as slow as normal....

0 0

I had at first misinterpreted the timestamp implementation of OAuth into thinking that it meant a timestamp that was not within 30 seconds past the current time would be denied, it turned out this was wrong for a few reasons including the fact that we could not guarantee that each system clock was in sync enough down to the minutes and seconds regardless of time zone. Then I read it again to get more clarity:

"Unless otherwise specified by the Service Provider, the timestamp is expressed in the number of seconds since January 1, 1970 00:00:00 GMT. The timestamp value MUST be a positive integer and MUST be equal or greater than the timestamp used in previous requests."


Meaning the timestamps are only compared in relation to previous requests from the same source, not in comparison to my server system clock.

Then I read a more detailed description here:...

0 0

Typical client-server communication during a nonce-based


process including both a server nonce and a client nonce.

In cryptography, a nonce is an arbitrary number that may only be used once. It is similar in spirit to a nonce word, hence the name. It is often a random or pseudo-random number issued in an authentication protocol to ensure that old communications cannot be reused in replay attacks. They can also be useful as initialization vectors and in cryptographic hash function.


A nonce is an arbitrary number used only once in a cryptographic communication, in the spirit of a nonce word. They are often random or pseudo-random numbers. Many nonces also include a timestamp to ensure exact timeliness, though this requires clock synchronization between organizations. The addition of a client nonce ("cnonce") helps to improve the security in some ways as implemented in digest access authentication. To ensure that a nonce is...

0 0
0 0

I think the safest nonce factory to use for 32-bit nonces is TimestampIncrementingNonceFactory -- for an argumentation see eg. #851 . (It's not 100% bullet proof, but that's because of issues inherent to HTTP APIs and the limitation of 32 bits.)

(This is when 32-bit nonces are required; with 64-bit nonces, a simple millisecond timestamp (CurrentTimeNonceFactory) is simpler and better.)

I changed Poloniex impl to use TimestampIncrementingNonceFactory by default in ca17be6. Please report if this behaves any better. (The new nonce factory will produce larger nonces than the previous one (unless you've been constantly making more than 4 requests per second) so the same API keys should continue...

0 0
0 0

In Part 1 we took a look at the incentives involved in Bitcoin mining and how they are used guarantee a single transaction history needed to prevent bitcoins from being double spent. In this post we will take more a technical look at the cryptography involved and how it is used to secure the network. As I said previously, Bitcoin is very accessible. While we will be discussing cryptographic concepts, it shouldn’t discourage you from continuing further.

Cryptographic Hash Functions

Before moving forward we should take a moment to learn about hash functions since they are used all throughout the Bitcoin protocol. To put it simply, a hash function is just a mathematical algorithm that takes an input and turns it into an output. For example, suppose we have an algorithm which just adds all the digits in the input string together. If our input is 1234 we would get an output of 10.

1234 ==> 10

Simple enough. However, there are certain properties of really good hash...

0 0

A nonce is a "number used once" to help protect URLs and forms from certain types of misuse, malicious or otherwise. WordPress nonces aren't numbers, but are a hash made up of numbers and letters. Nor are they used only once, but have a limited "lifetime" after which they expire. During that time period the same nonce will be generated for a given user in a given context. The nonce for that action will remain the same for that user until that nonce life cycle has completed.

WordPress's security tokens are called "nonces" despite the above noted differences from true nonces, because they serve much the same purpose as nonces do. They help protect against several types of attacks including CSRF, but do not protect against replay attacks because they aren't checked for one-time use. Nonces should never be relied on for authentication or authorization, access control. Protect your functions using current_user_can(), always assume Nonces can be compromised.

For an example...

0 0

Hdout tmj Hutmors

Qhrun Zphfmyhyh


Qhrun Zphfmyhyh ks hn @DH !knhncj" erhfuhtj #ro` $hrsjj @on%jj nstktutj o# @hnhej`jnt 'tufkjs $@ @'",@u`dhk. (rkor to tmht, mj co`pijtjf mks D.)jcm wktm `h%ors kn n#or`htkon )jcmnoioey. *j mhs h worb j+pjrkjncjo# - yjhrs hnf ks currjntiy worbkne hs h onsuithnt wktm oenk/hnt Dusknjss onsuitkne D ". *ks j+pjrtksj ikjskn tmj D!' fo`hkn, wktm spjckhi kntjrjst kn trhns#or`htkonhi tjcmnoioekjs. *ks phsskon #or prodij` soivkne mhs drouemt mk` to tmj foorstjps o# `hnhej`jnt consuitkne. *j ks hn hvkf rjhfjr hnf h spkrktuhi sjjbjr.

@omkt Smhr`h-

@omkt 'mhr`h ks hn @DH ) & 'uppiy mhkn", erhfuhtj #ro` $htkonhi nstktutj o# nfustrkhi @hnhej`jnt $ ) 7", @u`dhk. @omkt mhs co`pijtjf mks D.)jcm wktm `h%ors kn 7ijctronkcs & o``unkchtkons. *j ks currjntiyworbkne hs h onsuithnt wktm oenk/hnt Dusknjss onsuitkne D " hnf mhs ovjrhii worb j+pjrkjncj o# 8- yjhrs.@omkt mhs j+pjrtksj kn D!' fo`hkn hnf mhs hiso worbjf #or cikjnts...

0 0

How can I check on the status of my transaction?

Can I cancel, override, overwrite, replace, or do anything once a transaction has been sent?

99.9999999999999999% of the time the answer is NO.

Once a transaction has been mined and is included in a block on the blockchain, it cannot be canceled or replaced.

During times of normal volume, transactions are mined within seconds and do not spend any length of time in the transaction pool. There is simply not enough time to cancel or replace or override a transaction once it has been sent.


During times of extremely high volume (like we've seen during the Bancor and Status Token Contribution periods), transactions could be pending for hours, if not days, before being mined.

During these times it is theoretically possible to replace an existing transaction with a new transaction with a higher gas price.

The second transaction, theoretically, will be mined before the...

0 0

Only one of my boards is hashing and the Kernel Log is clearly indicating that something is wrong. Please help me interpret what I need to do

Things I've tried:

1. Reboot

2. Upgrade firmware

3. Curse fervently at computer

--- check asic number
The min freq=700
set real timeout 52, need sleep=379392
After TEST CRC error counter=0
search freq for 1 times, completed chain = 2, total chain num = 2
set_reset_allhashboard = 0x0000ffff
set_reset_allhashboard = 0x00000000
restart Miner chance num=2
waiting for receive_func to exit!
waiting for pic heart to exit!
Start bmminer ...
Detect 1GB control board of XILINX
Miner Type = R4
set_reset_allhashboard = 0x0000ffff
set_reset_allhashboard = 0x00000000
set_reset_allhashboard = 0x0000ffff
set_reset_allhashboard = 0x0000ffff
Error of set PIC FLASH addr: addr_H=f(0) addr_L=a0(0) on Chain[5]

0 0

Is it finding a key by brute force method for the newly generated hash of the newly generated block?

This is the first part of the problem.

Previous block hash + Version + Transactions (merkle root) + Time + Difficulty + Nonce = New block hash

With all of this information being static, only by changing the nonce (and sometimes transaction order, called extranonce) can you attempt to generate different block hashes.

The tricky part you're missing is the difficulty of the block hash, which is adjusted roughly every 14 days.

New block hash = SHA256 hash *Valid* block hash = SHA256 hash which is preceded by X number of zeros. (Simplified)


Block #450,827 is 0000000000000000023deabe6c71b7b15eff0a13a2e9871ee8796549d3693efb Block #150,000 is 0000000000000112f644be7e7ee3bb716017d729327bd196139a92446fb71f21 Block # 50,000 is 000000001aeae195809d120b5d66a39c83eb48792e068f8ea1fea19d84a4278a

You can easily see the difference in difficulty in generating...

0 0
0 0

Yes, I'm solo mining, and I'm using --scrypt (speed in kh/s).

I'll try a pool, but I got the following in the debug logs --

2013-12-17 23:31:30] GPU 0 found something? [2013-12-17 23:31:30] OCL NONCE 129605 found in slot 0 [2013-12-17 23:31:30] [thread 0: 1048576 hashes, 119.0 khash/sec] [2013-12-17 23:31:30] GPU0: invalid nonce - HW error [2013-12-17 23:31:30] OCL NONCE 183595 found in slot 1 [2013-12-17 23:31:30] GPU0: invalid nonce - HW error [2013-12-17 23:31:30] OCL NONCE 205151 found in slot 2 [2013-12-17 23:31:30] GPU0: invalid nonce - HW error [2013-12-17 23:31:30] OCL NONCE 348676 found in slot 3 [2013-12-17 23:31:30] GPU0: invalid nonce - HW error [2013-12-17 23:31:30] OCL NONCE 361138 found in slot 4 [2013-12-17 23:31:30] GPU0: invalid nonce - HW error [2013-12-17 23:31:30] OCL NONCE 455330 found in slot 5 [2013-12-17 23:31:30] GPU0: invalid nonce - HW error [2013-12-17 23:31:30] OCL NONCE 516499 found in slot 6 [2013-12-17 23:31:30] GPU0: invalid nonce - HW...
0 0

This item has been corrected.

If you clicked the button above, then you are currently mining bitcoin, the math-based digital currency that recently topped $1,000 on exchanges. Congratulations. (It won’t do anything bad to your computer, we promise.)

New bitcoins are created roughly every 10 minutes in batches of 25 coins, with each coin worth around $730 at current rates. Your computer—in collaboration with those of everyone else reading this post who clicked the button above—is racing thousands of others to unlock and claim the next batch.

For as long as that counter above keeps climbing, your computer will keep running a bitcoin mining script and trying to get a piece of the action. (But don’t worry: It’s designed to shut off after 10 minutes if you are on a phone or a tablet, so your battery doesn’t drain).

So what is that script doing, exactly?

Let’s start with what it’s not doing. Your computer is not blasting through the cavernous depths of...

0 0
0 0
0 0
0 0

Your home can have the kind of beautiful moldings they say no one installs anymore!


Molding Pattern I use this term to describe a specific design that is made up of multiple pieces of molding and or flat-stock, such as CROWN MOLDING-106 or BASEBOARD-110. See all of my DIY Molding Projects here.

Molding Profile This term is used when referring to an individual piece of molding or millwork, such as BB-001 or CM-003. See all the molding profiles I’ve used here on my DIY Molding Inventory page.

I developed these principles over the last nineteen years while teaching myself how to design and install affordable moldings, and they outline my very specific approach to decorating with moldings. I hope they help you too.

1. You Don’t Need to Be a Woodworker

Simple tools and techniques.

The Joy of Moldings is a decorating with moldings blog — not a woodworking blog.

So you don’t need to be an experienced finish...

0 0

new 3.5 in-depth course:

Introduction to Bitcoin, Blockchain and Decentralized projects (Ethereum)


The goal of this video is to explain how Bitcoin works under the hood, to give a clearer idea of what it really means to own, send or “mine” Bitcoins.

New: Turkish translation by now available.

If, instead of how it works, you're looking for where to buy Bitcoin, I use coinbase. And for trading, check out bitcoin wealth alliance (both affiliate links).

What is Bitcoin at a high level?

First, a brief high-level overview of what Bitcoin is.

At its core, Bitcoin is just a digital file that lists accounts and money like a ledger. A copy of this file is maintained on every computer in the Bitcoin network. (update: you don't have to maintain a ledger just to use Bitcoin to send and receive money, this is for people who want to help maintain the system).

These numbers...
0 0
0 0