If you're seeing this message, it means we're having trouble loading external resources on our website.Khan Academy -- the not-for-profit, online learning site whose mission is "a free world-class education for anyone anywhere" -- has leapt with both feet into the theory and technology of bitcoin.Earlier this week, the academy uploaded seven instructional videos about bitcoin onto its Finance and Capital Markets section.(The videos also appear on Khan Academy's YouTube channel.)Ranging in length from 10:14 to 12:14, all the videos are presented by computer security and cryptography expert Zulfikar Ramzan.Currently the chief scientist for the cloud technology group at Sourcefire, Ramzan previously worked with Immunet, Symantec, DoCoMo Labs and Alcatel-Lucent.He earned a PhD in electrical engineering and computer science from the Massachusetts Institute of Technology.The new Khan Academy titles include: In the overview video, Ramzan focuses on the details of how a single transaction works, rather than attempting to summarize the workings of the overall bitcoin system.

"The bitcoin scheme is fairly involved ... ," he explains."(T)he best way to really wrap your head around a scheme like bitcoin is to really suspend belief for a bit and get exposed to all these relevant details."The posting of the new Khan Academy videos was met with a lot of enthusiasm from the bitcoin community.noted Bitcoin Forum member Mike Christ."I was already a fan of Khan academy, but this is great.Reaffirms the fact that bitcoin is only going to get more and more popular.""I’ve been saying for a long LONG time now that education is past due for a serious overhaul, and Khan Academy has been the front-runner in the race for education’s future," wrote David Perry, author of the Coding in my Sleep blog."(A)nd now they’re teaching bitcoin."Perry added, "While there are admittedly bigger stories to be found in the bitcoin world right now, as an education reformer, YouTuber and long-time fan of the good work Khan Academy is doing, I have to say this has me pretty excited."Reddit's bitcoin fans also expressed excitement, though it was somewhat tempered by Ramzan's use of technical terms that "average people" might not understand.

"I hope the introduction doesn't scare the audience away," commented redditor tmalsburg2.User JackPerth added, "Don't forget to donate to Khan academy :)" ... which drew the logical response from someone going by the name bitroll: "As soon as they add a bitcoin donation option!"wert pro bitcoinOffered is an 8-part Bitcoin series taught by Zulfikar Ramzan, a world-leading expert in computer security and cryptography.rig for litecoinBitcoin Video Series (from Khan Academy website) YouTube playlist of the 8 part seriesbitcoin yazılımıSi estás viendo este mensaje, significa que estamos teniendo problemas para cargar materiales externos en nuestro sitio.ethereum nzd

The Khan Academy now supports donations in bitcoins.The news was announced last week on Coinbase's blog, as the non-profit educational website is using the US company's merchant tools to accept bitcoin payments.ethereum declineThe Khan Academy offers a large range of educational resources.bitcoin getting down to virtual currency basicsThere are videos and exercises for students.bitcoin als anlageLessons are hosted on YouTube and offered up on the Khan Academy website in formatted courses.ethereum truthThere's even a course about bitcoin, among all the other courses in world history, physics, mathematics, etc. There are also tools for tutors to interact with students.mine litecoin online

According to Coinbase's blog post, you will earn a "special badge" on your profile page for making a donation to Khan Academy in bitcoin, in addition to the badges that students can earn for completing courses, etc. A bitcoin supporter told us: "It seemed only right that I should donate some BTC to Khan Academy for their excellent bitcoin tutorial videos.All I had to do was scan a QR code on the screen to send them a small donation of 0.05BTC.The donation process was smooth, and I was even awarded an 'I am Satoshi' badge for my trouble."Darragh Browne of Blockspin commented: "This is great news as the Khan Academy is democratising education in the same way that bitcoin is democratising financial services.There is already a big tipping culture in the bitcoin community, so it's great to see the Khan Academy tapping into this.Hopefully, other non-profits will follow suit and adopt bitcoin as another revenue stream to receive appreciation for their work."The Khan Academy was founded by Salman Khan.

You can donate by following this link.Time sure does fly!A new generation of programmers are already leapfrogging over Bitcoin and directly into Ethereum.These programmers may never have taken much interest in cryptocurrencies, but they’re drawn to Ethereum by its provisioning for trustless transactions of arbitrary (turing-complete!)While I can’t blame them for wanting to jump right into Ethereum, Ethereum derives a huge share of its underlying technology directly from Bitcoin.This series of articles will describe just enough of Bitcoin for budding Ethereum developers to better understand how Ethereum works under the hood, then begin to explore some routes by which new Ethereum devs can begin developing contract-orientation just like they developed their sense of object-orientation back in the day.This is part one of a two part series.Part one, “Just Enough Bitcoin for Ethereum”, will focus on understanding Bitcoin.Part 2, “Ethereum: Bitcoin Plus Everything”, will focus on the ways in which Ethereum extends Bitcoin’s blockchain technology.A blockchain is fundamentally a public record of state changes.

Anybody can audit a blockchain’s state changes over time and prove for themselves with mathematical certainty whether those transactions were made in accordance with the blockchain’s rules.In the case of Bitcoin, those rules are simple: Bitcoins can’t be double-spent, and their origin must be traceable back to the mining of a valid block (more on mining later).To begin our journey, I recommend reading the Bitcoin whitepaper even if you know nothing about cryptography.We’ll loop back to the cryptographic underpinnings afterwards.The Bitcoin whitepaper is short, and only the first six sections are of real interest to us.Cryptographic Underpinnings of Blockchain TransactionsAs somebody with absolutely no background in cryptography, I found myself confused beginning with the white paper’s description of transactions.We should understand that this is a scheme designed to prove ownership over an asset at a given time by tracing that asset’s history of owners up to the present.But what’s a public key?

How do these help us to prove ownership of an asset?If you’ve never taken a cryptography class, watch the videos from Khan Academy below for a good high-level description of these important functions.(SatoshiNakamoto, Bitcoin: A Peer-to-Peer Electronic Cash System)Now let’s look back at the white paper’s transaction diagram.Here we are hashing both Owner 2’s public key and the previous transaction (in which the Bitcoin entered Owner 1’s possession) into a single digest (the output of the hashing function).This digest is then signed with Owner 1’s private key.In the future, anyone can verify Owner 2’s claim on that Bitcoin by inputting the state change she/he insists occurred to a signature verification algorithm: a sum of Bitcoin and Owner 2’s public key (signifying a transfer of that sum to Owner 2), Owner 1’s public key (signifying that this transfer of Bitcoin originated from Owner 1), and the transaction’s signed form (a digest available publically on the blockchain, recorded there when the transaction took place).

Only if the exact state change Owner 2 specifies was indeed signed with Owner 1’s private key will Owner 1’s public key assert the signed transaction digest’s validity relative to the signed transaction on-chain.This process can be repeated recursively going back to the Bitcoin’s origin to prove the complete ownership chain is valid.You probably have a lot of questions at this point and are already considering edge cases — how does the ownership chain begin?How are specific sums of Bitcoin specified for transfer?Amazingly, there’s not much more of Bitcoin you need to understand for Ethereum’s sake.Next we’ll cover sections three through six of the whitepaper and figure out how some of those edge cases are resolved.The Role of Mining in Creating Network Consensus on the BlockchainAll bitcoin transactions are broadcast to the entire network, and these transactions are collected by miners who verify those transaction’s validity (essentially using the method described previously) and include all valid transactions into a “block.” The contents of the block are then hashed with an incrementing random number (called a “nonce”) until the resulting output contains a certain number of leading zeroes.

The network dynamically adjusts the requisite number of leading zeroes (or the “difficulty”) so that a block is mined every 10 minutes on average.Because the results of hashing algorithms are unpredictable, finding a valid hash which the rest of the network will accept requires both luck and CPU power.The more computational power one possesses, the greater their chances of finding a valid hash before anyone else in the network.When a valid block is “mined,” it is broadcast to and tested by the rest of the network.The other nodes test whether the included state transitions make sense given the most-recent canonical block, that all the transaction signatures pass for valid and that the block and the provided nonce hash to a valid digest before accepting the block as the newest canonical network state.The block is then added to the head of the existing “chain” of previously mined blocks in each node’s local database.Bitcoin is safe so long as at least 51% of the computational power for all the nodes connected to the network is controlled by honest, non-colluding users.

A malicious user controlling 51% of the network who pays for his coffee with Bitcoin could drink his brew and then mine a block (starting at the state just before his transaction) which fraudulently omitted his coffee purchase.Even if the network had gotten a few blocks ahead of him by the time he started mining his fraudulent chain, with 51% of the network’s horsepower he would inevitably catch up.Because the Bitcoin protocol requires that the longest chain be accepted as canonical, the malicious user would get away with his theft even if there existed abandoned subtrees of the blockchain suggesting his deceit.You now have all the knowledge you need to understand the fundamentals of how the Bitcoin blockchain works.Don’t feel bad if you don’t totally get it yet: try sleeping on it for a few days and it’ll start coming together in your dreams.Once it does, you might be able to begin imaging how something a lot like the Bitcoin blockchain could be used to verify the public outputs of arbitrarily complex computations when the inputs and program code are publicly shared as well.