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Authenticated encryption – Wikipedia

Authenticated encryption (AE) and authenticated encryption with associated data (AEAD) are forms of encryption which simultaneously assure the confidentiality and authenticity of data. These attributes are provided under a single, easy to use programming interface.

The need for AE emerged from the observation that securely combining separate confidentiality and authentication block cipher operation modes could be error prone and difficult.[1][2] This was confirmed by a number of practical attacks introduced into production protocols and applications by incorrect implementation, or lack of authentication (including SSL/TLS).[3]

Around the year 2000, a number of efforts evolved around the notion. In particular, strong interest in these modes was sparked by the publication of Charanjit Jutla’s IACBC and IAPM modes[4] in 2000. Six different authenticated encryption modes (namely OCB2.0, Key Wrap, CCM, EAX, Encrypt-then-MAC (EtM), and GCM) have been standardized in ISO/IEC 19772:2009.[5] More were developed in response to NIST solicitation.[6] Sponge functions can be used in duplex mode to provide authenticated encryption.[7]

A typical programming interface for AEmode implementation would provide the following functions:

The header part is intended to provide authenticity and integrity protection for networking or storage metadata for which confidentiality is unnecessary, but authenticity is desired.

In addition to protecting message integrity and confidentiality, authenticated encryption can provide security against chosen ciphertext attack. In these attacks, an adversary attempts to gain an advantage against a cryptosystem (e.g., information about the secret decryption key) by submitting carefully chosen ciphertexts to some “decryption oracle” and analyzing the decrypted results. Authenticated encryption schemes can recognize improperly-constructed ciphertexts and refuse to decrypt them. This in turn prevents the attacker from requesting the decryption of any ciphertext unless he generated it correctly using the encryption algorithm, which would imply that he already knows the plaintext. Implemented correctly, this removes the usefulness of the decryption oracle, by preventing an attacker from gaining useful information that he does not already possess.

Many specialized authenticated encryption modes have been developed for use with symmetric block ciphers. However, authenticated encryption can be generically constructed by combining an encryption scheme and a message authentication code (MAC), provided that:

Bellare and Namprempre (2000) analyzed three compositions of these primitives, and demonstrated that encrypting a message and subsequently applying a MAC to the ciphertext (the Encrypt-then-MAC approach) implies security against an adaptive chosen ciphertext attack, provided that both functions meet the required properties. Katz and Yung investigated the notion under the name “unforgeable encryption” and proved it implies security against chosen ciphertext attacks.[8]

In 2013, a competition was announced to encourage design of authenticated encryption modes.[9]

AEAD is a variant of AE where the data to be encrypted needs both authentication and integrity as opposed to just integrity. AEAD binds associated data (AD) to the ciphertext and to the context where it’s supposed to appear, so that attempts to “cut-and-paste” a valid ciphertext into a different context are detected and rejected.

It is required, for example, by network packets. The header needs integrity, but must be visible; payload, instead, needs integrity and also confidentiality. Both need authenticity.

The plaintext is first encrypted, then a MAC is produced based on the resulting ciphertext. The ciphertext and its MAC are sent together. Used in, e.g., IPsec.[10] The standard method according to ISO/IEC 19772:2009.[5] This is the only method which can reach the highest definition of security in AE, but this can only be achieved when the MAC used is “strongly unforgeable”.[11] In November 2014, TLS and DTLS extension for EtM has been published as RFC 7366. Various EtM ciphersuites exist for SSHv2 as well (e.g.

A MAC is produced based on the plaintext, and the plaintext is encrypted without the MAC. The plaintext’s MAC and the ciphertext are sent together. Used in, e.g., SSH.[12] Even though the E&M approach has not been proved to be strongly unforgeable in itself,[11] it is possible to apply some minor modifications to SSH to make it strongly unforgeable despite the approach.[citation needed]

A MAC is produced based on the plaintext, then the plaintext and MAC are together encrypted to produce a ciphertext based on both. The ciphertext (containing an encrypted MAC) is sent. Used in, e.g., SSL/TLS.[13] Even though the MtE approach has not been proven to be strongly unforgeable in itself,[11] the SSL/TLS implementation has been proven to be strongly unforgeable by Krawczyk who showed that SSL/TLS was in fact secure because of the encoding used alongside the MtE mechanism.[14][dubious discuss] Despite the theoretical security, deeper analysis of SSL/TLS modeled the protection as MAC-then-pad-then-encrypt, i.e. the plaintext is first padded to the block size of the encryption function. Padding errors often result in the detectable errors on the recipient’s side, which in turn lead to padding oracle attacks, such as Lucky Thirteen.

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Bitcoin Price Today – Live Bitcoin Value – Charts & Market …

Last year everyone was going bonkers for Bitcoin, and thats no surprise, seeing as how the number one cryptocurrency had an absolutely explosive price performance in 2017. Things have cooled off in 2018 as prices fell significantly, however many are still bullish about Bitcoins long-term potential.

To that end, the scarce, deflationary quality of Bitcoin makes it totally unlike traditional fiat currencies, which are usually prone to inflation and even hyperinflation in the worst of cases. That means as more investments pour into BTC, its price will likely continue to see upward pressure because there will be no supply response.

Think about how when the price of oil surges, more companies begin producing oil, which then increases the supply and acutely deflates the price of oil accordingly.

No similar supply response can never happen with bitcoins. There will never be more than ~21 million, and even contemporary estimations say more than 3 million BTC have been lost for good, making BTC considerably scarcer than many realize.

That means the BTC could potentially shoot up exponentially in future years. But how high?Lets take a look at some of the more prominent projections weve seen thrown around in recent days.

Once renowned for being a prominent Wall Street hedge fund manager, Mike Novogratz has now set his sights on the cryptocurrency space, and hes not turning back. Running the crypto-based Galaxy Investment Partners, Novogratz is betting big on the Bitcoin boom in general as his mid-term BTC price projection suggests.

Bitcoin could be at $40,000 at the end of 2018, Novogratz said. It easily could.

And for Novogratz, theres no confusion as to why that particular price point may end up really materializing. In a November 30th interview on Fox Business, Novogratz unabashedly declared that Bitcoin is going mainstream.

And Novogratz knows what mainstream and institutional looks like; he used to run a Goldman Sachs trading desk in Asia before becoming a hedge fund manager at Fortress. If he thinks the herd is coming, as it were, then we all best pay attention.

Going much more long-term, Novogratz said it was within the realm of possibility that the bitcoin market cap could one day reach the current market cap of gold, which is around a whopping $8 trillion USD.

If this reality were to materialize down the road, that would put each BTC around the $390,000 price point.

Firebrand Bitcoin pundit Max Keiser has never made his love for BTC and its potential a secret.

As such, youll commonly find him on Twitter making new price predictions based on the Bitcoin booms momentum.

For now, hes pegging his short-term bitcoin price target at $15,000. Thats a reasonable figure, to be sure, especially with BTCs parabolic price performance in Q3 and Q4 2017.

Beyond that, though, Keiser has his eye set on the impressive $100,000 BTC price milestone.

Love him or hate him, Adam Back is an OG cypherpunk whos made incalculable contributions to the cryptocurrency space as a whole. Theres a reason Satoshi Nakamoto reached out to Back (and Wei Dai) first in starting up Bitcoin.

In other words, Backs been around the block once or twice. He knows the ecosystem as well as anyone.

And its his opinion that the next major target for the bitcoin price to hit is $100,000, echoing Max Keisers aforementioned prediction.

In a recent tweet, Back even went as far to say that users should be careful selling bitcoin in 2018 because the price could rocket so acutely over the next 12 months that people wouldve made considerably more by just holding.

John McAfee is best known as the creator of the popular McAfee antivirus software. Hes also become a Bitcoin aficionado over the past several months, and he never hesitates to voice his opinions on the cryptocurrency craze accordingly.

And his opinions are exceedingly bullish, to say the least. McAfee was projecting $500,000 BTC in 2020 just a few weeks ago, but he modified his claim to be even more bold as bitcoins market surge has been moving faster than he anticipated.

Now, McAfee thinks $1 million per bitcoin will be reality by the end of 2020. Thats almost an unfathomable possibility at the moment, but maybe we havent seen anything yet. Especially if institutional interest keeps exploding.

But McAfee has even bolder ideas, to be sure. In an even newer Twitter exchange, McAfee explained that he believes the BTC price could reach into the billions one day.

Specifically, the tens of billions as he argues:

Thats certainly the most aggressive price prediction anyones made for BTC yet. But if that insane price materializes, McAfee will end up looking like even more of a madman genius than he already is.

Swedish Pirate Party founder Rick Falkvinge is a big proponent of Bitcoin Cash (BCH), going so far as to sarcastically call himself the CEO of Bitcoin Cash.

But that doesnt mean he doesnt respect the beast that BTC is and could be.

Bitcoin] can easily go to more than $1 million per bitcoin. Falkvinge said during a recent interview. But thats just Falkvinges conservative estimate. Hes actually more bullish than that, asserting that BTC can go as high as $5 million:

If cryptocurrency fulfills its promise, and theres no indication it wouldnt, then the equivalent of one bitcoin needs to be in the $2-5 million dollar range.

The cryptocurrency expert and venture capitalist, Tim Draper, has also given its opinion about the future price of Bitcoin. According to him bitcoin and blockchain technology are one of the best things that happened for businesses.

Mr Draper said in 2014 that Bitcoin could reach $10,000 in just three years, something that happened in 2017, exactly on the date he predicted. When he explained that bitcoin could reach that price ($10,000), the cryptocurrency was traded just at $413 dollars.

At the same time, he said that in the future Bitcoin could keep growing. About that, he is convinced that the cryptocurrency is the future and that the virtual currency market will gain its place among fiat currencies.

Bitcoin is the future currency. Why would I sell the future for the past? Why would I go and grab some weird fiat subject to the will of some governments? he commented during an interview with Bloomberg.

The world market for cryptocurrencies is 6 trillion dollars, and I think that that it will be crypto. And I am really excited about all the extraordinary things that can happen because of crypto and bitcoin.

Cameron Winklevoss is one of the two popular Winklevoss twins. The co-founder of the cryptocurrency exchange Gemini, stated that bitcoin could be worth 40 times its current value.

In order to explain why bitcoin could grow up to 40 times, he compared the cryptocurrency market capitalization with the market cap of gold.

During an interview with CNBC he said:

So if you look at a $100 billion market cap today, now last week it might have been more like 200, so its actually a buying opportunity, we think that theres a potential appreciation of 30 to 40 times because you look at the gold market today, its a $7 trillion market. And so a lot of people are starting to se that, they recognize the store of value properties.

He has also said that due to the fact that bitcoin has a fixed supply, it is still a very underappreciated asset. Indeed, he stated that he and his brother believe that bitcoin disrupts gold.

The Winklevoss twins emphasized that they will not sell their bitcoins even if the price surpasses $380,000 dollars. This is a special number, because if bitcoin reaches this price level, its market capitalization will be equal to golds market valuation.

An important portfolio manager that worked for more than six years in the cryptocurrency world, predicted this year that Bitcoin could reach $50,000 dollars. While speaking at the World Economic Forum in Davos, he brought some calm to the cryptocurrency market. Bitcoin could definitely see $50,000 in 2018.

At the moment of the statement, Bitcoin was traded over $11,000, days later it reached the lowest point in months when it was displayed in cryptocurrency exchanges under $6,000 dollars.

But Mr Singh said that the kind of volatility that bitcoin experienced is not unusual nor unexpected. And thats confirmed when we pay attention to the charts. In the past, Bitcoin suffered important corrections in just a few days.

Mr Singh commented:

If you look at Microsoft of Apple when they went public their stocks were very volatile because the market wasnt mature. There are not so many vendors right now who can accept cryptocurrencies but theres huge adoption on the black market.

Cryptocurrency adoption keeps growing all over the world. In past articles we wrote that enterprises are investing in blockchain technologies and virtual currencies. Businesses all around the world, including small shops and merchants, are adopting bitcoin and other currencies as a means of payment.

If the adoption trend continues, bitcoin could lead the market towards new all time highs. Additionally, payment processors are working with cryptocurrencies trying to spread their benefits.

Lets get really speculative just for the purposes of illustration the growth thats possible in the coming years.

The current market cap of all global stock markets is around $100 trillion USD. Woah, right? Accordingly, lets say that the entire cryptocurrency market one day reaches this $100 trillion cap.

And lets also say that BTC maintains its current position as hovering around a 50 percent share of the entire crypto market (though, of course, theres no reason to believe itll stay at 50 percent forever).

That would put Bitcoin as having around a $50 trillion market cap. At this point, all we need is to divide $50 trillion by the number of bitcoins in existence.

Lets go with 17 million instead of 21 million since many bitcoins have been lost already.

Alas: $50 trillion divided by 17 million = ~$2,941,176. Round up, and thats $3 million per bitcoin.

Now, we cant count our eggs before theyve hatched. Theres still quite the mountain to climb for the crypto market to get even close to hitting $100 trillion. But maybe its possible in 30 or 40 years. Maybe not at all.

Its going to be a wild ride no matter what happens between now and then, that much is for sure.

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Suite of Crypto Services to Leverage Nasdaq Framework …

Nasdaq and Bcause have announced that a suite of new cryptocurrency services will be offered via the Nasdaq Financial Framework. These services include crypto mining and custody solutions, as well as spot and derivatives trading. They are expected to attract a broad range of users including a new breed of investors wanting to participate in the growing cryptocurrency marketplace.

Also read: SEC Chair Explains Key Upgrades Needed for Bitcoin ETF Approval

Nasdaq Inc. and Bcause Llc announced on Wednesday that a suite of crypto services will leverage Nasdaqs technology, elaborating:

Bcauses markets will operate on Nasdaqs matching engine, clearing and market surveillance technology via the Nasdaq Financial Framework platform.

The Nasdaq Financial Framework consists of a single operational core that ties together the deep portfolio of Nasdaqs proven business functionality across the trade lifecycle, in an open framework, the company detailed.

Launched last year with a mining facility in Virginia Beach, Virginia, Bcause is building what it calls a full-stack cryptocurrency ecosystem which it also claims to be the worlds first. According to the announcement, the services to be offered via Nasdaqs framework are all parts of the digital currency value chain, from a custody solution to the mining facility in Virginia Beach, to spot trading for digital assets, to a futures market and derivatives clearinghouse. The technology is expected to go live in the first half of this year with the launch of the Bcause spot cryptocurrency market.

In addition, Bcause revealed that it has filed with the U.S. Commodity Futures Trading Commission (CFTC) to become a designated contract market (DCM) and to establish a derivative clearing organization (DCO). The CFTC website describes that DCMs may list for trading futures or option contracts based on any underlying commodity, index or instrument.

Wednesdays announcement further states:

Once derivatives trading and clearing officially commence, Bcause will be the only venue to serve as a one-stop shop for all parts of the digital currency value chain: from the state-of-the-art digital mining facility launched in February 2018, to spot trading for digital assets, to a futures market and derivatives clearinghouse which are pending regulatory approval.

Nasdaq explained that its market technology is already being used by broker-dealers, exchanges, clearinghouses, central securities depositories and regulators in over 50 countries. In February, the bourse began tracking the prices of BTC and ETH with real-time price data.

Nasdaq also offers a digital asset surveillance technology, which it believes will help Bcause monitor its markets for manipulative activities and misconduct to benefit the security of the crypto spot and derivatives markets.

I fully expect that our markets will attract a broad range of users, Bcause CEO Fred Grede expressed, from those who are already quite active in the financial markets and familiar with Nasdaq technology, to a new breed of investors wanting to participate in the growing cryptocurrency marketplace. Paul McKeown, Nasdaqs Senior VP and Head of Marketplace Operators and New Markets, Market Technology, commented:

By leveraging the Nasdaq Financial Framework, Bcause will have the scalability and modular functionality to introduce new micro-services and expand its business offerings to meet industry demands and the evolution of the digital assets economy.

What do you think of this new suite of crypto services leveraging Nasdaqs technology? Let us know in the comments section below.

Images courtesy of Shutterstock.

Need to calculate your bitcoin holdings? Check our tools section.

A student of Austrian Economics, Kevin found Bitcoin in 2011 and has been an evangelist ever since. His interests lie in Bitcoin security, open-source systems, network effects and the intersection between economics and cryptography.

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Email Encryption Options for MDaemon Email Server

MDaemon uses a layered approach to email encryption for safely sending your emails and attachments. On the client-side, MDaemon Webmail users can enable basic encryption features when sending emails and attachments within Webmail. On the server-side, Administrators have the ability to use encryption, decryption, and basic key management capabilities.

MDaemon Webmail uses HTTPS connections to power its webmail encryption

MDaemon supports Open PGP to power its server-side email encryption

When composing a message, MDaemon Webmail users can use the Advanced Options screen to instruct MDaemon to encrypt the message, retrieve their public key, or retrieve the public key of another user (if available). This greatly simplifies the process of sending secure, encrypted email using MDaemon PGP.

On the server side, OpenPGP for MDaemon has been added to give administrators the ability to use encryption, decryption, and basic key management capabilities through OpenPGP support.

This additional layer helps administrators who want to ensure user compliance by managing encryption settings at the server versus the user implemented client level. Also, MDaemon’s Content Filter now contains actions to encrypt and decrypt messages. And finally, server-side encryption capabilities are beneficial when using email archiving with MDaemon.

MDaemon Webmail has a unique setting that allows it to be used as basic public key server. When this feature is enabled, Webmail will honor requests for your users’ public keys using a specially formatted URL. Additionally, MDaemon’s OpenPGP feature supports collection of public keys over DNS. This helps to automate the process of exchanging encryption keys.

MDaemon’s OpenPGP features can verify embedded signatures found within messages. This helps the recipient ensure that the message is authentic. MDaemon Webmail will display an icon or text label for verified messages. Webmail will also display labels for messages with valid DKIM signatures, messages decrypted by OpenPGP, and messages signed with an OpenPGP key.

Automated Encryption Key Exchange allows the process of exchanging public keys for OpenPGP to take place during the SMTP message delivery process. When this feature is enabled, authorized users will no longer need to manually send their public key to another user from whom they wish to receive encrypted email.

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ZOOM Web Hosting and Domain Registration Philippines is a …

ZOOM Domain Registration and Cloud, SSD Web Hosting Philippines gives business the advantage of getting the benefit of real cloud SSD web hosting platform for the price of traditional shared web servers or VPS hosting. Unlike other website hosting and domain registration companies with servers that run mostly on Centos, our Cloud platform are powered by CloudLinux, the only OS designed to optimize web server performance in a cloud environment. This means that spikes from one tenant doesnt affect other tenants making each account stable and running smoothly.

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Dont just take our word for it, try it now and experience the best, lightning fast cloud web hosting today! Dedicated Cloud-based VPS and Dedicated server also available.

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Quantum computing for everyone | Michael Nielsen

Can you give me a simple, concrete explanation of how quantum computers work?

Ive been asked this question a lot. I worked on quantum computing full time for 12 years, wrote 60 or so papers, and co-authored the standard text. But for many years the question stumped me. I had several pat answers, but none really satisfied me or my questioners.

It turns out, though, that there is a satisfying answer to the question, which anyone can understand if theyre willing to spend some time concentrating hard.

To understand the answer, lets back up and think first about why big media outlets like the New York Times and the Economist regularly run stories about quantum computers.

The reason is that quantum computer scientists believe quantum computers can solve problems that are intractable for conventional computers. That is, its not that quantum computers are like regular computers, but smaller and faster. Rather, quantum computers work according to principles entirely different than conventional computers, and using those principles can solve problems whose solution will never be feasible on a conventional computer.

In everyday life, all our experience is with objects which can be directly simulated by a conventional computer. We dont usually think about this fact, but movie-makers rely on it, and we take it for granted special effects are basically just rough computer simulations of events that would be more expensive for the movie makers to create in real life than they are to simulate inside a computer. Much more detailed simulations are used by companies like Boeing to test designs for their latest aircraft, and by Intel to test designs for their latest chips. Everything youve ever seen or done in your life driving a car, walking in the park, cooking a meal all these actions can be directly simulated using a conventional computer.

Because of this, when we think in concrete terms we invariably think about things that can be directly simulated on a conventional computer.

Now, imagine for the sake of argument that I could give you a simple, concrete explanation of how quantum computers work. If that explanation were truly correct, then it would mean we could use conventional computers to simulate all the elements in a quantum computer, giving us a way to solve those supposedly intractable problems I mentioned earlier.

Of course, this is absurd! Whats really going on is that no simple concrete explanation of quantum computers is possible. Rather, there is an intrinsic quantum gap between how quantum computers work, and our ability to explain them in simple concrete terms. This quantum gap is what made it hard for me to answer peoples requests for a concrete explanation. The right answer to such requests is that quantum computers cannot be explained in simple concrete terms; if they could be, quantum computers could be directly simulated on conventional computers, and quantum computing would offer no advantage over such computers. In fact, what is truly interesting about quantum computers is understanding the nature of this gap between our ability to give a simple concrete explanation and whats really going on.

This account of quantum computers is distinctly at odds with the account that appears most often in the mainstream media. In that account, quantum computers work by exploiting what is called quantum parallelism. The idea is that a quantum computer can simultaneously explore many possible solutions to a problem. Implicitly, such accounts promise that its then possible to pick out the correct solution to the problem, and that its this which makes quantum computers tick.

Quantum parallelism is an appealing story, but its misleading. The problem comes in the second part of the story: picking out the correct solution. Most of the time this turns out to be impossible. This isnt just my opinion, in some cases you can mathematically prove its impossible. In fact, the problem of figuring out how to extract the solution, which is glossed over in mainstream accounts, is really the key problem. Its here that the quantum gap lies, and glossing over it does nothing to promote genuine understanding.

None of my discussion to now actually explains how quantum computers work. But its a good first step to understanding, for it prepares you to expect a less concrete explanation of quantum computers than you might at first have hoped for. I wont give a full description here, but I will sketch whats going on, and give you some suggestions for further reading.

Quantum computers are built from quantum bits, or qubits [1], which are the quantum analogue of the bits which make up conventional computers. Heres a magnified picture of a baby quantum computer made up of three Beryllium atoms, which are used to store three qubits:

The atoms are held in place using an atom trap, which you cant see because its out of frame, but which surrounds the atoms, holding them suspended in place using electric and magnetic fields, similar to the way magnets can be used to levitate larger objects in the air.

The atoms in the picture are about three micrometers apart, which means that if you laid a million end to end, they wouldnt quite span the length of a living room. Very fine human hair is about 20 micrometers in diameter itd pretty much cover the width of this photo.

The atoms themselves are about a thousand times smaller than the spacing between the atoms. They look a lot bigger in the picture, and the reason is interesting. Although the atoms are very small, the way the picture was created was by shining laser light on the atoms to light them up, and then taking a photograph. The particles making up the laser light are much bigger than the atoms, which makes the picture come out all blurry; the photo above is basically a very blurry photograph of the atoms, which is why they look so much bigger than they really are.

I called this a baby quantum computer because it has only three qubits, but in fact its pretty close to the state of the art. Its hard to build quantum computers, and adding extra qubits turns out to be tricky. Exactly who holds the record for the most qubits depends on who you ask, because different people have different ideas about what standards need to be met to qualify as a genuine quantum computer. The current consensus for the record is about 5-10 qubits.

Okay, a minor alert is in order. Ive tried to keep this essay as free from mathematics as possible, but the rest of the essay will use a little high-school mathematics. If this is the kind of thing that puts you off, do not be alarmed! You should be able to get the gist even if you skip over the mathematical bits.

How should we describe whats inside a quantum computer? We can give a bare-bones description of a conventional computer by listing out the state of all its internal components. For example, its memory might contains the bits 0,0,1,0,1,1, and so on. It turns out that a quantum computer can also be described using a list of numbers, although how this is done is quite different. If our quantum computer has n qubits (in the example pictured above n = 3), then it turns out that the right way to describe the quantum computer is using a list of 2n numbers. Its helpful to give these numbers labels: the first is s1, the second s2, and so on, so the entire list is:

What are these numbers, and how are they related to the n qubits in our quantum computer? This is a reasonable question in fact, its an excellent question! Unfortunately, the relationship is somewhat indirect. For that reason, Im not going to describe it in detail here, although you can get a better picture from some of the further reading I describe below. For us, the thing to take away is that describing n qubits requires 2n numbers.

One result of this is that the amount of information needed to describe the qubits gets big really quickly. More than a million numbers are needed to describe a 20-qubit quantum computer! The contrast with conventional computers is striking a conventional 20-bit computer needs only 20 numbers to describe it. The reason is that each added qubit doubles the amount of information needed to describe the quantum computer [2]. The moral is that quantum computers get complex far more quickly than conventional computers as the number of components rises.

The way a quantum computer works is that quantum gates are applied to the qubits making up the quantum computer. This is a fancy way of saying that we do things to the qubits. The exact details vary quite a bit in different quantum computer designs. In the example I showed above, it basically involves manipulating the atoms by shining laser light on them. Quantum gates usually involve manipulating just one or two qubits at a time; some quantum computer designs involve more at the same time, but thats a luxury, its not actually necessary. A quantum computation is just a sequence of these quantum gates done in a particular order. This sequence is called a quantum algorithm; it plays the same role as a program for a conventional computer.

The effect of a quantum gate is to change the description s1, s2, of the quantum computer. Let me show you a specific example to make this a bit more concrete. Theres a particular type of quantum gate called a Hadamard gate. This type of gate affects just one qubit. If we apply a Hadamard gate to the first qubit in a quantum computer, the effect is to produce a new description for the quantum computer with numbers t1, t2, given by

t1 = (s1+s2n/2+1)/ 2

t2 = (s2+s2n/2+2)/ 2,

t3 = (s3+s2n/2+3)/ 2,

and so on, down through all 2n different numbers in the description. The details arent important, the salient point is that even though weve manipulated just one qubit, the way we describe the quantum computer changes in an extremely complicated way. Its bizarre: by manipulating just a single physical object, we reshuffle and recombine the entire list of 2n numbers!

Its this reshuffling and recombination of all 2n numbers that is the heart of the matter. Imagine we were trying to simulate whats going on inside the quantum computer using a conventional computer. The obvious way to do this is to track the way the numbers s1, s2, change as the quantum computation progresses. The problem with doing this is that even a single quantum gate can involve changes to all 2n different numbers. Even when n is quite modest, 2n can be enormous. For example, when n = 300, 2n is larger than the number of atoms in the Universe. Its just not feasible to track this many numbers on a conventional computer.

You should now be getting a feeling for why quantum computer scientists believe it is infeasible for a conventional computer to simulate a quantum computer. Whats really clever, and not so obvious, is that we can turn this around, and use the quantum manipulations of all these exponentially many numbers to solve interesting computational problems.

I wont try to tell that story here. But if youre interested in learning more, heres some reading you may find worthwhile.

In an earlier essay I explain why conventional ways of thinking simply cannot give a complete description of the world, and why quantum mechanics is necessary. Going a little further, an excellent lay introduction to quantum mechanics is Richard Feynmans QED: The Strange Theory of Light and Matter. It requires no mathematical background, but manages to convey the essence of quantum mechanics. If youre feeling more adventurous still, Scott Aaronsons lecture notes are a fun introduction to quantum computing. They contain a fair bit of mathematics, but are written so you can get a lot out of them even if some of the mathematics is inaccessible. Scott and Dave Bacon run excellent blogs that occasionally discuss quantum computing, and their blogrolls are a good place to find links to other quantum bloggers.

Finally, if youve enjoyed this essay, you may enjoy some of my other essays, or perhaps like to subscribe to my blog. Thanks for reading!

Thanks to Jen Dodd and Kate Nielsen for providing feedback that greatly improved early drafts of this essay.

Michael Nielsen is a writer living near Toronto, and working on a book about The Future of Science. If youd like to be notified when the book is available, please send a blank email to with the subject subscribe book. Youll be emailed to let you know when the book is to be published; your email address will not be used for any other purpose.

[1] Ben Schumacher, who coined the term qubit, runs an occasional blog.

[2] Motivated by this observation, in my PhD thesis I posed a tongue-in-cheek quantum analogue of Moores Law: to keep pace with conventional computers, quantum computers need only add a single qubit every two years. So far, things are neck and neck.

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Hundreds of Millions in Cryptocurrency Vanishes After …

(Newser) A CEO’s untimely death, hard-to-crack passwords, and up to $190 million in missing cryptocurrency. These all underlie a mystery that Fortune calls the “implosion of Quadriga” after the December death of the QuadrigaCX coin exchange’s chief, Gerald Cotten, at the age of 30, and now the FBI and Royal Canadian Mounted Police are reportedly involved. Cotten allegedly died in India of Crohn’s disease complications, and he was the only one with access to the accounts of 115,000 Quadriga customersbut he apparently didn’t leave his passwords with anyone, including his widow. The auditor Ernst & Young did manage to eventually get into the exchange, but it did so to a shocking find: All the digital wallets were cleaned out, per the BBC, which notes most of the funds were originally thought to be in “cold storage,” meaning they weren’t supposed to be accessible via the internet.

However, the E&Y report found 14 user accounts Cotten had “created outside the normal process,” and CoinDesk poked around the transaction records and found indications someone moved the missing currency to “hot wallets” on other exchanges. Some even wonder if Cotten faked his own death, per Fortune. The upshot for Quadriga customers, per reporter Amy Castor, who offers a timeline of what happened with the exchange: “All of your money is gone.” There’s a $100,000 reward on the missing funds from Kraken, another cryptocurrency exchange, whose CEO, Jesse Powell, wants to both help his own customers who lost money through Quadriga and also keep the reputation of the cryptocurrency market overall intact. “I … think you’ve got to get the family and staff and shareholders in a room for a few hours of interrogation to get to the bottom of what’s going on,” he tells Fortune. (Read more cryptocurrency stories.)

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Cloud Storage Providers – SourceForge

The Best Cloud Storage Services for 2019

If you are individual who wants to store your photos and music to the cloud, the 3 providers below provide one of the best cloud storage solutions around. When you are storing personal data, chances are you dont need a lot of features like the business owners do.


The cloud is one of the biggest phrases in telecommunications, yet many businesses are not using the cloud. In fact, some users still find the cloud to be a daunting thing. But this is because they dont know how the cloud can greatly benefit their business. One of the big things a business can do to help boost their efficiency and speed is to invest in cloud storage.

Simply put, the cloud storage provides an online space where users can store and share data. It is an important tool for businesses that want secure data storage that can be accessed by employees in any location. Choosing a cloud storage solution takes a bit of research; but once you settle on a cloud storage solution, you will be able to start taking advantage of all the cloud has to offer.

There are four types of cloud storage: personal, public, private, and hybrid. Below we detail each of them to help you better understand your options:

the most common version of this is mobile device backups.Consumersalso use personal cloud services for documents, photos, music and more.

An online storage space that has minimal admin controls and can be accessed by anyone who is authorized.

Typically a companys own data center, either onsite or externally hosted. It gives you the freedom to design the system to meet your needs.

A combination of public and private. You can choose what data gets stored where.

Businesses that are not using any type of cloud storage system are certainly missing out on a number of things. Here are a few of the benefits that choosing a cloud storage provider can bring to your business:

the most common version of this is mobile device backups.Consumersalso use personal cloud services for documents, photos, music and more.

With a cloud storage service,you greatly increase your businessreach. Cloud storage allows you access data from anywhere, and doesnt require you to have costly onsite hardware to store your data. Also, most cloud storage services have multiple distributed data centers in case of failover or natural disasters. This way, you always have access to your data.

cloud storage solutions offer topnotch security that aims at keeping all of your data safe. Most cloud storage services use encryption, thirdparty validation, security software, and more to ensure that your data is protected.

compared to hosting and updating your own equipment, a cloud storage serviceis much more affordable. Plus, cloud storage will help to minimize the time and money you spend on routine backups and system upgrades.

Cloud storage services are widely available, for either personal or private use. Names like Dropbox, Box, Google Drive, and more are some of the more common names that youve likely heard of. But how do you know what to look for in the best cloud storage solution? Here are a few things to keep in mind:

ensure that you caneasily use,manage,organize,share,and access your cloud storage. A good cloud storage solution will be easy to use and will integrate seamlessly with your operating systems, both mobile and desktop.

in case of an emergency or a natural disaster, you want to make sure that your cloud storage solution has recovery practices in place.

know what type of security measures your cloud storage service uses in order to protect your data. Things like encryption, data protection, authorization, and should be important to you for your security.

be sure to compare pricing across all solutions sothat you meet your needs for the best price. A majority of cloud storage services offer affordable rates that wont break the bank.

Last update: 2016-06-08

Formerly AjaXplorer, file sharing platform for the enterprise

Last update: 2013-04-02

A simple to use drag and drop web interface to manage files online.

Last update: 2016-10-07

Legacy Release only. Get latest Edition here:

Last update: 2019-02-24

BTRFS based NAS and private cloud storage solution

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Fidelity’s new cryptocurrency company is up and running …

An ongoing cryptocurrency bear market is not dampening interest for Fidelity’s new institutional cryptocurrency products.

Fidelity Digital Assets, a new company created by the investing giant last year, has quietly rolled out its cryptocurrency custody and trade execution operations. In the past few months it has been up and running with institutional investors like hedge funds and family offices, according to its top executive.

The collapse in cryptocurrency prices over the last year “haven’t had an impact” on getting up and running, Tom Jessop, head of Fidelity Digital Assets told CNBC at the DC Blockchain Summit this week. “If you started a crypto fund at the height of the market you’re probably hurting right now.”

Bitcoin, along with thousands of other digital coins, sparked a buying frenzy among retail investors in late 2017. The world’s largest cryptocurrency has dropped more than 80 percent since its high of almost $20,000 at the end of 2017 and was trading near $3,789 on Friday.

Still, Jessop said there’s long-term interest from institutional investors to add some form of cryptocurrency to their portfolios. It’s often seen as an uncorrelated risk, or a store of value in a crisis. Others see a trading opportunity given the sector’s volatility. Fidelity commissioned research to gauge the level of that interest.

The firm interviewed roughly 450 institutions, everyone from wealthy families to hedge funds, pensions and endowments. About 22 percent of the respondents already own cryptocurrency, according to the findings. Those that already own it expect to double their allocation over five years.

“If anything, they are as encouraged now as they were when prices were higher,” Jessop said.

Fidelity’s new company will execute trades on multiple exchanges for these professional investors. It also handles custody, or the safe storage of digital assets. Until Fidelity, there had been a noticeable lack of a big U.S.-based company in that business.

Jessop said while the company is live, certain aspects are still a work in progress. Fidelity is expanding the jurisdictional coverage of where it can do business. And its offerings are not one-size-fits-all. Some customers were using the platform in January, while for other customers, it was March. Others may wait until September, he said.

“It really depends on the facts and circumstances of each client,” Jessop said.

Fidelity, a roughly 72-year-old family-controlled firm, is known for managing retirement plans and mutual funds. But it also spends $2.5 billion per year on technologies like artificial intelligence and blockchain. The new digital asset company was born out of the Fidelity Center for Applied Technology, or FCAT as employees call it.

Jessop said many institutional investors are still in “wait and see” mode when it comes to putting money into crypto.

“At some point, there will be an attractive entry point,” Jessop said. “But by the same token people don’t want to be early even if we’re well off the highs.”

Much of that hesitation has to do with volatility, he said. The digital currency market has been known to jump or sink by 10 percent in a single day. While prices in 2019 have been relatively stable, institutions are still wary of those sudden price moves, according to the Fidelity survey. That issue should be solved as the market structure matures, Jessop said.

Education is another roadblock to greater acceptance by investors. Jessop said the more educated a firm was on the topic, the more likely they were to be holding cryptocurrency.

“They’ve approached us wanting to learn, which is an encouraging sign,” Jessop said. “That’s not to say that there’s a cohort of people that once they get educated will still have a negative view.”

WATCH:How to start your very own cryptocurrency

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The Best Cloud Storage Services for Backup in 2019

Cloud storage services are great for sharing files with friends and families, keeping documents in sync between all of your devices, and so much more. Free cloud storage is even better!

Yes, there really areno-strings-attached, free cloud storage services out there. Many of them, actually.While nearly all have premium offerings that provide more space, the free cloud storage offered is usually more than enough for most people.

Better yet, many of these free online storage providers give you even more free space for referring friends or performing other tasks.

Cloud storage is different than automatic cloud backup. The services listed below are great for keeping your files kept online for storage, sharing, and playback, but they will not keep your computer files backed up online on a schedule.


10 GB of free online storageis offered by pCloud, with friend referrals and other bonus stepsjumping it to a possible 20 GB.

A desktop client can be installed for Windows, Mac, and Linux operating systems. There’s also a mobile app that’s very intuitive and easy to use.

pCloudsupports adding files from a remote URL in addition to single file and whole folder uploads through a browser. The mobile apps can upload photos and videos directly to your pCloud account.

Both files and folders can both be shared with non-users. Shared folders can even be downloaded as a ZIP archive.

Also, pCloud allows upload links to be generated for folders so anyone can send files to your account. A unique email address is also generated which lets you (or anyone)email files directly to a folder on your pCloud account.

In addition to the above, you can backup the photos from your social media accounts like Facebook, Instagram, and Picasa.

Get pCloud for iPhone, iPad, Android, Windows Phone, and more.


Dropbox users start off with 2 GB of free space with several simple ways of earning more, up to around 18 GB.

You can view and upload all your Dropbox files from a desktop or mobile app and share whole folders with anyone, even if they don’t have a Dropbox account.

If you have Microsoft Office files stored in your Dropbox account, you can edit them from inside your browser for free using Microsoft Office Online.

Get Dropbox for Android, iPhone, iPad, Kindle Fire, Windows Phone, BlackBerry, or your computer.

Useful amount of storage.

Cross-platform mobile apps.

Unique file sharing permissions.

No public access to shared folders.

Tiny upload file size limit.

Unfriendly website interface.

New FlipDrive users get 10 GB of initial storage with an opportunity for more for each friend they can refer to start using FlipDrive.

There is a mobile app that can be used for uploading files to FlipDrive, but the website works, too. If you use the web version, you can upload whole folders using the website, which is nice.

You can share files with anyone, even if they don’t have a FlipDrive account. However, accessing sharedfolders requires a registered FlipDrive account.Recipients can be given write, edit, delete, and share permissions in addition to read rights for folders.

You can create up to 10 shared links and upload files that are as large as 25 MB.

The FlipDrive website isn’t the easiest to use when compared to most other cloud storage services, which is a bummer, but it still manages to function if you can work through it.

FlipDrive downloads are available for iPhone, iPad, Android, Windows, and Windows Phone devices.

Google Drive is the cloud storage service offered by Google. Each new user gets 15 GB of free space.

The total storageis actuallyshared with other Google services, like Gmail and Google+ Photos. If you don’t use the other services, you canutilize almost all the space for Google Drive alone.

A sync client can be installed for desktop users, which supports folder and file uploads. There’s also a mobile app that can sendphotos and videos to Google Drive.

Folders and files can be shared with specific Google users via their email address or anyone with a public link. You can also make a file view-only, which prevents someone from downloading it.

Google Drive makes it really simple to collaborate with others by allowing comments and letting files be opened and accessed my more than one person at a time.

Get Google Drive for iPhone, iPad, Android, or your Mac or Windows computer.


Works with Microsoft Office Online.

Many ways to upload files.

Control how files are shared.

Earn more storage for free.

OneDrive (formerly called SkyDrive) is an online storage service from Microsoft. Everyone gets 5GB of free space when they sign up.

Extra hosting can be awarded if you follow certain instructions, like friend referrals and mobile photo syncing.

A desktop program can be installed to easily transfer folders and files of any type to OneDrive, making them accessible from a mobile device. The mobile app can also upload files both images and videos.

OneDrive supports sharing both folders and files with non-registered users. A permission can be set to only allow viewing or to allow full editing.

You can get the OneDrive app for Windows, Android, iPhone, iPad, and Xbox One.


Get 5 GB of free online storage space with HiDrive. If you refer friends to join, you can increase your storage up to 10 GB.

If you’re aWindows or Mac user, youcan connect to your account over WebDAV, which makes it really simple to drag and drop new files to your account.

An app is available that supports mobile photo and video uploads.

When sharing files, you’re required to set the URL to expire after a certain number of days and also set a maximum number of allowed downloads before the link becomes invalid.

You can also share folders, and recipients, even non-users, can download all the files at once in an archive.

The HiDrive app is available for iPhone, iPad, and Android.


Yandex is a Russian company known mainly for its popularYandex Searchand Yandex Email services, but they also have others, like Yandex.Disk for 10 GB of free cloud storage for anyone who creates an account.

There are plenty of useful features with Yandex.Disk, such as public and privatefolder and file sharing, the ability to import photos via social networks,bulk downloads, automatic mobile uploads, and support for drag and drop.

Windows, Mac, and Linux users can install a desktop program to upload files to Yandex.Disk, and a mobile app is available for Android, iPhone, and iPad. Inc.

Complete tasks to earn more free space.

Web-based folder uploads.

Collaborate with team folders.

Password protect shares.

Not ideal for large files like videos.

Can’t cancel web uploads.

Minimal but functional website.

5 GB can of free cloud storage can be had when you sign up for Sync.

Like some of the other services listed on this page, Sync can upload multiple files at once through both the website interface as well as the mobile and desktop app.

You can build shared folders that other users can interact with as well as share any folder or file withanyone, regardless if they’re a Sync user.

Vaultis a folder in Sync that you can put files into so that they aren’t synced across your other devices. This is useful if you just want to archive some files online but don’t need them elsewhere.

See Sync’sfeatures page for a list of its features and some comparisons between the free and pro versions.

This service is available from not only the web but also Windows, Mac, iPhone, iPad, and Android.


MyDrive is another online storage service but it offers much less space than the majority of the others in this list.There is no limit to how large uploads can be, but you can only store up to 100 MB on MyDrive, which makes the maximum file size 100 MB as well.

MyDrive is very limited compared to similar websites, such as the fact that file sharing is allowed only if you give out a “guest” username and password, and you only get one.

Though I do like thatyou can download multiple files in an archive andrestore deleted files up to a month after removing them from your account.

Adesktop appis available for Windows, Linux, andMac computers, and an Android and iOS app for mobile devices. Plus, you can connect to your account through WebDAV.


Another website that gives out quite a bit of online space is Tencent Cloud at However, while there is 10 GB of free storage up for grabs, the website and app are not in English, making it pretty difficult to use them.

With that being said, if you’re out of options and need these 10 gigabytes, the upload and download buttons are easy enough to understand since they’re just pictures.

You can check how much space you have available from this page.

To get logged in to Tencent Cloud, you can download the WeChat app on your phone (it’s in English) and use theDiscover > Scanoption to scan the QR code on, which will get you in and let you use the cloud storage features (use the QR code from the right tab).

Tencent Cloud can be downloaded for Windows, Mac, Android, iPhone, and iPad.

More storage than most services.

Apps for mobile and desktop.

Automatically upload files.

Multiple ways to earn more free storage space.

Works more like a backup service.

No external hard drive support.

Can’t view saved files on the website.

Degoo gives out a huge 100 GB of free storage to anyone who makes an account.

If you have lots of friends who want to use Degoo to store their files, you can even get 500 GBmoreby referring them to make an account. You get 3 GB for each person that joins through your referral. You can also watch ads to get more free online space (1.2 GB per day).

I’ve placed Degoo at the very bottom of this list despite its huge 100 GB capacity because it functions a bit more like a backup service rather than a cloud storage program.

You can definitely pick which files are backed up but backups are performed automatically every 24 hours to keep things updated, which makes it work more like a free backup service.

Because Degoo is a bit different than these other cloud storage services, you should use it like this: pick a folder on your computer that will hold all of your backed up files, or make new one. Put everything into that folder that you want to keep online, and then make sure Degoo is running to back up the files online.

You can use the cloud storage account on your computer through the desktop program, or access your files on the go with the mobile app for iPhone, iPad, and Android.

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