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# How Long Is A Bitcoin Private Key?

## How Much Time To Crack A Private Key?

Actually my question is how much time at 1 TH/s is needed to crack any of the top 10000 holding btc addresses? what if someone start a pool to crack any of those keys? someone can "protect" spliting holdings in a few accounts, but if only a key is cracked that would hurt BTC very bad. So, how much time is needed to crack any key? not a specific one, supouse The script keeps a bunch of keys in memory and with each iteration tries to brake any of them. If you see garbage posts (off-topic, trolling, spam, no point, etc.), use the "report to moderator" links. All reports are investigated, though you will rarely be contacted about your reports. Advertised sites are not endorsed by the Bitcoin Forum. They may be unsafe, untrustworthy, or illegal in your jurisdiction. Advertise here. If we built a Dyson sphere around the sun and captured all its energy for 32 years, without any loss, we could power a computer to count up to 2192. Of course, it wouldnt have the energy left over to perform any useful calculations with this computer. But thats just one star, and a measly one at that. A typical supernova releases something like 1051 ergs. If all of this energy could be channelled into a single orgy of computation, a 219-bit counter could be cycled through all of its states. These numbers have nothing to do with the technology of the devices; they are the maximums that thermodynamics will allow. And they strongly imply that brute-force attacks against 256-bit keys will be infeasible until computers are built from something other than matter and occupy something other than space. Quote from: Carlos L. on January 29, 2013, 04:44:09 PM This question has been answered 999999999999999999999 times. I missed them. However a brute force attack would be much easied by the fact that the pri Continue reading >>

## The Length Of The Bitcoin's Private Keys

In Bitcoin, a private key is usually a 256-bit number ... Although it is a silly question, is this length safe? Based on this site , Elliptic Curve 256 bit keys are safe until 2040. Does Bitcoin network change its key size in that far future?? If Bitcoin reaches 2040, what happens to many wallets that use 256 bit keys? Bitcoin uses the secp256k1 elliptic curve with 256 bit private/public key pair cryptography to render ECDSA functionality. The two bitcoin explorer (bx) commands below replicate statements/results in the site references above. Note the private key is a 256-bit hexadecimal encoded number. % echo "e9873d79c6d87dc0fb6a5778633389f4453213303da61f20bd67fc233aa33262" | bx base58check-encode -v 128 5Kb8kLf9zgWQnogidDA76MzPL6TsZZY36hWXMssSzNydYXYB9KF - is the associated uncompressed private key that is encoded using base58 check, also called Wallet Input Format (WIF). % echo "e9873d79c6d87dc0fb6a5778633389f4453213303da61f20bd67fc233aa33262" | bx ec-to-public -u | bx ec-to-address -v 0 1CC3X2gu58d6wXUWMffpuzN9JAfTUWu4Kj - is the address corresponding to the associated uncompressed public key. If I were a hacker that wanted to compromise secp256k1, I would first compromise the top 100 rich list wallets that are not using multisig first. Bitcoin is the most excellent canary in the cryptographic coal mine to determine when secp256k1 fails. The banking system would never be such a good crypto-Samaritan. From Table 1 the elliptic curve subject matters experts assert the strength of a 256-bit secp256k1 private key has the strength of 128 bits of encryption when the associated public key is exposed. To brute force attack a public key to obtain a public key with 128 bits of entropy will cost at least \$100M in electricity at 5 cents per KW-Hr using almost perfectly efficie Continue reading >>

## How To Generate Your Very Own Bitcoin Privatekey

Founder of @Longcaller. Interested in distributed systems, game design, and cryptoeconomic primitives. Write about cryptocurrencies. How to generate your very own Bitcoin privatekey In cryptocurrencies, a private key allows a user to gain access to their wallet. The person who holds the private key fully controls the coins in that wallet. For this reason, you should keep it secret. And if you really want to generate the key yourself, it makes sense to generate it in a secure way. Here, I will provide an introduction to private keys and show you how you can generate your own key using various cryptographic functions. I will provide a description of the algorithm and the code in Python. Most of the time you dont. For example, if you use a web wallet like Coinbase or Blockchain.info, they create and manage the private key for you. Its the same for exchanges. Mobile and desktop wallets usually also generate a private key for you, although they might have the option to create a wallet from your own private key. So why generate it anyway? Here are the reasons that I have: You want to make sure that no one knows the key You just want to learn more about cryptography and random number generation (RNG) Formally, a private key for Bitcoin (and many other cryptocurrencies) is a series of 32 bytes. Now, there are many ways to record these bytes. It can be a string of 256 ones and zeros (32 * 8 = 256) or 100 dice rolls. It can be a binary string, Base64 string, a WIF key , mnemonic phrase , or finally, a hex string. For our purposes, we will use a 64 character long hex string. The same private key, written in different formats. Why exactly 32 bytes? Great question! You see, to create a public key from a private one, Bitcoin uses the ECDSA, or Elliptic Curve Digital Signature Algori Continue reading >>

## What Is A Bitcoin Private Key?

A private key is just a number picked at random. The private key is used to generate the public key through an irreversible process. In the case of Bitcoin the Private key is turned into the Public key through Elliptic Curve C ryptography or ECC for short. If you lose your private key you can't access your Bitcoins, and if someone else finds it out they can steal them. A Private key is just a long number and in the case of a Bitcoin it is a number between 1 & 1.158x 10^77. In practice this number is generated using a secure random number generator that is then fed into the SHA-256 hashing algorithm. The SHA-256 hashing algorithm takes a string of numbers and outputs a 256 bit number which then has to be checked to see if it is less than 1.158x 10^77. When creating your private key most software will do this under the hood, but if you choose certain methods on your own such as 1x10^77 or other certain obvious numbers and then hash via the SHA-256 hackers can create rainbow tables and match to your private key, public key and address. If you do this and choose a particular phrase you are reducing the entropy or chaos of your choice! Always opt for randomness just to be safe even if the chances are very small. The point of using Elliptic curve cryptography is to find a method whereby you can create a Bitcoin Public Key easily Bitcoin Private Key but not the reverse i.e. find the Bitcoin Private Key from its Public Key. This is due to the discrete logarithm problem for elliptic curves, where the best mathematical solutions to break elliptic curve cryptography have to take step proportional to 2n/2 , where n is the length of the number which the Bitcoin key has to below (1.158x 10^77) (also known as the field size the curve is based on for modular arithmetic). In practice t Continue reading >>

## 4. Keys, Addresses, Wallets - Mastering Bitcoin [book]

Ownership of bitcoin is established through digital keys, bitcoin addresses, and digital signatures. The digital keys are not actually stored in the network, but are instead created and stored by users in a file, or simple database, called a wallet. The digital keys in a users wallet are completely independent of the bitcoin protocol and can be generated and managed by the users wallet software without reference to the blockchain or access to the Internet. Keys enable many of the interesting properties of bitcoin, including de-centralized trust and control, ownership attestation, and the cryptographic-proof security model. Every bitcoin transaction requires a valid signature to be included in the blockchain, which can only be generated with valid digital keys; therefore, anyone with a copy of those keys has control of the bitcoin in that account. Keys come in pairs consisting of a private (secret) key and a public key. Think of the public key as similar to a bank account number and the private key as similar to the secret PIN, or signature on a check that provides control over the account. These digital keys are very rarely seen by the users of bitcoin. For the most part, they are stored inside the wallet file and managed by the bitcoin wallet software. In the payment portion of a bitcoin transaction, the recipients public key is represented by its digital fingerprint, called a bitcoin address, which is used in the same way as the beneficiary name on a check (i.e., Pay to the order of). In most cases, a bitcoin address is generated from and corresponds to a public key. However, not all bitcoin addresses represent public keys; they can also represent other beneficiaries such as scripts, as we will see later in this chapter. This way, bitcoin addresses abstract the recip Continue reading >>

## Private Key. All About Cryptocurrency - Bitcoin Wiki

A private key in the context of Bitcoin is a secret number that allows bitcoins to be spent. Every Bitcoin address has a matching private key, which is saved in the wallet file of the person who owns the balance. The private key is mathematically related to the Bitcoin address, and is designed so that the Bitcoin address can be calculated from the private key, but importantly, the same cannot be done in reverse. Because the private key is the "ticket" that allows someone to spend bitcoins, it is important that these are kept secure. Private keys can be kept on computer files, but they are also short enough that they can be printed on paper. An example of a utility that allows extraction of private keys from your wallet file for printing purposes is pywallet. In order to create a transaction with a private key, it must be available to a program or service that allows entry or importing of private keys. Some wallets allow the private key to be imported without generating any transactions while other wallets or services require that the private key be swept. When a private key is swept, a transaction is broadcast that sends the entire balance held by the private key to another address in the wallet or securely controlled by the service in question. An example of private key sweeping is the method used on MtGox's Add Funds screen and BIPS Import screen. Just as with any other deposit, there is risk of double-spending so funds are deposited to the MtGox account after a six-confirmation wait (typically one hour). In contrast BlockChain .info's My Wallet service and Bitcoin-QT each provide a facility to import a private key without creating a sweep transaction [1] . In Bitcoin, private key is a 256-bit number, which can be represented one of several ways. Here is a private ke Continue reading >>

## Is It Possible For Someone To Guess A Private Key To A Bitcoin Wallet And Steal The Coins?

If you use a Brainwallet then yes, somebody can guess your private key as you can use dictionaries and brute force attack it. For a true random generated wallet the probability of guessing is unpractical. Here is a private key in hexadecimal - 256 bits in hexadecimal is 32 bytes, or 64 characters in the range 0-9 or A-F. E9873D79C6D87DC0FB6A5778633389F4453213303DA61F20BD67FC233AA33262 This private key does not exist by the way. So you see, there are 64 characters, and each character is hexadecimal (can hold 16 different case insensitive values: {0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F} ), meaning there are $16^{64}$ possible private key combinations. The current world population is roughly $7.6$ billion. Assume everyone holds a wallet (meaning $~7,600,000,000$ private keys). Even with this imaginary best case scenario, the success rate of randomly guessing a private key correctly is: $~ 100 \cdot \frac{7,600,000,000}{16^{64}} = 0.0000000000000000000000000000000000000000000000000000000000000000065634881018717779152936274157283036740481602769715738$% So even if you had the computing power of Sunway TaihuLight (a Chinese supercomputer which, as of November 2016, is ranked number one in the TOP500 list as the fastest supercomputer in the world), which is about $9.3 \cdot 10^{16} = 93,000,000,000,000,000$ floating point operations per second (flops), then giving there are $86,400$ seconds a day and about $365$ days a year, and (falsely) assuming it takes 1 flop to generate a private key and 0 time to check for its correctness, then a correct guess would probably occur once every- [math]\frac{1}{365} \cdot \frac{(\frac{16^{64}}{7,600,000,000})}{(86400 \cdot (9.3 \cdot 10^{16}))} =~ 5194882658574989737995779 Continue reading >>