Where is bitcoin wallet stored

Encrypting your wallet or your smartphone allows you to set a password for anyone trying to withdraw any funds. This helps protect against thieves, though it cannot protect against keylogging hardware or software. You should make sure you never forget the password or your funds will be permanently lost.

Unlike your bank, there are very limited password recovery options with Bitcoin. In fact, you should be able to remember your password even after many years without using it. In doubt, you might want to keep a paper copy of your password in a safe place like a vault.

Any password that contains only letters or recognizable words can be considered very weak and easy to break. A strong password must contain letters, numbers, punctuation marks and must be at least 16 characters long. The most secure passwords are those generated by programs designed specifically for that purpose.

Strong passwords are usually harder to remember, so you should take care in memorizing it. An offline wallet, also known as cold storage, provides the highest level of security for savings.

It involves storing a wallet in a secured place that is not connected to the network. When done properly, it can offer a very good protection against computer vulnerabilities. Using an offline wallet in conjunction with backups and encryption is also a good practice.

Here is an overview of some approaches. This approach involves having two computers sharing some parts of the same wallet. The first one must be disconnected from any network. It is the only one that holds the entire wallet and is able to sign transactions.

The second computer is connected to the network and only has a watching wallet that can only create unsigned transactions. This way, you can securely issue new transactions with the following steps. Add a comment.

Active Oldest Votes. It seems like what's called for here is a basic explanation of two of Bitcoin's big concepts: the wallet and the blockchain: A "wallet" is a collection of ECDSA keypairs. For those not familiar with cryptography, a keypair consists of a "public key" and a "private key" which can be used to encrypt or sign bits of data.

The public key, as the name suggests, is known to everyone and can be used to encrypt messages in such a way that the holder of the private key alone may decrypt them.

The private key may also be used to sign messages in such a way that anyone holding the public key may verify that the message truly came from you. Every Bitcoin address consists of such a keypair - the "address" you send people is the public half and the private half resides in your wallet.

The "blockchain" is a constantly growing database of transaction information which is sent out to all nodes in the Bitcoin network. When you perform a transaction, that transaction is distributed to the network and assuming the transaction is valid, will be included in the next "block. When you initiate a transaction, all previous transactions to or from that address are scanned and a balance is calculated. If your transaction exceeds this available balance, it will be rejected by the network and will not be included in a block.

Improve this answer. David Perry David Perry Excellent explaination, thanks. So you can really just store an offline backup of your wallet on a flash drive and you don't really need to run the wallet client actively until you want to make a transaction?

Are you sayng that every node on the bitcoin network contains the entire history of all transactions ever perfomed by bitcoin owners?

Second, what is a "node"? Any computer with a bitcoin wallet? It depends on what software you're using, actually. Way back when I wrote this answer there was really just the one wallet software and yes, it stored every single transaction ever. Today there are several options and not all of them store all data. Electrum, for example, runs thin clients which connect to servers that store the whole blockchain and many phone wallets only store blocks containing transactions that pertain to them.

In general, however, it is considered preferable for each node computer running software to store everything. David, thanks, but there are several vague things i cant understand. Show 4 more comments. David Schwartz David Schwartz To sum it up in a pair of sentences: Your coins are stored in addresses public keys , copies are made public and included in every node of the bitcoin network. Great explanation.

What happens when you lose your wallet. DeathAndTaxes "Coins" are not entities stored in the blockchain; they're just an abstraction on top of transaction info like balances.

David Schwartz ThePiachu ThePiachu Where is that block-chain database stored? A copy of it is stored on every computer running the Bitcoin software. Blockchain is distributively stored by computers running the Bitocoin software. Most clients do not store the complete blockchain as it is on the order of 1GB of size , but they store the transactions they are interested in as in, the ones that have coins that belong to them and the newest blocks.

Some clients, however, store the whole blockchain. So, everyone has some blocks, some people have all blocks, and there are multiple copies of the same block stored across the internet. ThePiachu, you're talking about a lightweight client which, to the best of my knowledge, has not yet been implemented. Currently all clients store the whole blockchain. Meni, it has been implemented but not in the main client.

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 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. The bitcoin address is the only representation of the keys that users will routinely see, because this is the part they need to share with the world.

In this chapter we will introduce wallets, which contain cryptographic keys. We will look at how keys are generated, stored, and managed. We will review the various encoding formats used to represent private and public keys, addresses, and script addresses. Finally, we will look at special uses of keys: to sign messages, to prove ownership, and to create vanity addresses and paper wallets. Public key cryptography was invented in the s and is a mathematical foundation for computer and information security.

Since the invention of public key cryptography, several suitable mathematical functions, such as prime number exponentiation and elliptic curve multiplication, have been discovered. These mathematical functions are practically irreversible, meaning that they are easy to calculate in one direction and infeasible to calculate in the opposite direction. Based on these mathematical functions, cryptography enables the creation of digital secrets and unforgeable digital signatures. Bitcoin uses elliptic curve multiplication as the basis for its public key cryptography.

In bitcoin, we use public key cryptography to create a key pair that controls access to bitcoins. The key pair consists of a private key and—derived from it—a unique public key. The public key is used to receive bitcoins, and the private key is used to sign transactions to spend those bitcoins.

There is a mathematical relationship between the public and the private key that allows the private key to be used to generate signatures on messages. This signature can be validated against the public key without revealing the private key.

When spending bitcoins, the current bitcoin owner presents her public key and a signature different each time, but created from the same private key in a transaction to spend those bitcoins.

Through the presentation of the public key and signature, everyone in the bitcoin network can verify and accept the transaction as valid, confirming that the person transferring the bitcoins owned them at the time of the transfer. In most wallet implementations, the private and public keys are stored together as a key pair for convenience.

However, the public key can be calculated from the private key, so storing only the private key is also possible. A bitcoin wallet contains a collection of key pairs, each consisting of a private key and a public key. The private key k is a number, usually picked at random.

From the private key, we use elliptic curve multiplication, a one-way cryptographic function, to generate a public key K. From the public key K , we use a one-way cryptographic hash function to generate a bitcoin address A. In this section, we will start with generating the private key, look at the elliptic curve math that is used to turn that into a public key, and finally, generate a bitcoin address from the public key.

The relationship between private key, public key, and bitcoin address is shown in Figure A private key is simply a number, picked at random. Ownership and control over the private key is the root of user control over all funds associated with the corresponding bitcoin address. The private key is used to create signatures that are required to spend bitcoins by proving ownership of funds used in a transaction. The private key must remain secret at all times, because revealing it to third parties is equivalent to giving them control over the bitcoins secured by that key.

The bitcoin private key is just a number. You can pick your private keys randomly using just a coin, pencil, and paper: toss a coin times and you have the binary digits of a random private key you can use in a bitcoin wallet. The public key can then be generated from the private key. The first and most important step in generating keys is to find a secure source of entropy, or randomness.

Usually, the OS random number generator is initialized by a human source of randomness, which is why you may be asked to wiggle your mouse around for a few seconds. For the truly paranoid, nothing beats dice, pencil, and paper. To create such a key, we randomly pick a bit number and check that it is less than n - 1.

In programming terms, this is usually achieved by feeding a larger string of random bits, collected from a cryptographically secure source of randomness, into the SHA hash algorithm that will conveniently produce a bit number.

If the result is less than n - 1 , we have a suitable private key. Otherwise, we simply try again with another random number. Study the documentation of the random number generator library you choose to make sure it is cryptographically secure. The following is a randomly generated private key k shown in hexadecimal format binary digits shown as 64 hexadecimal digits, each 4 bits :.

It is approximately 10 77 in decimal. The visible universe is estimated to contain 10 80 atoms. To generate a new key with the Bitcoin Core client see Chapter 3 , use the getnewaddress command. For security reasons it displays the public key only, not the private key. To ask bitcoind to expose the private key, use the dumpprivkey command. The dumpprivkey command shows the private key in a Base58 checksum-encoded format called the Wallet Import Format WIF , which we will examine in more detail in Private key formats.

The dumpprivkey command opens the wallet and extracts the private key that was generated by the getnewaddress command. It is not otherwise possible for bitcoind to know the private key from the public key, unless they are both stored in the wallet. The dumpprivkey command is not generating a private key from a public key, as this is impossible. The command simply reveals the private key that is already known to the wallet and which was generated by the getnewaddress command.

You can also use the command-line sx tools see Libbitcoin and sx Tools to generate and display private keys with the sx command newkey :. The public key is calculated from the private key using elliptic curve multiplication, which is irreversible: where k is the private key, G is a constant point called the generator point and K is the resulting public key. Elliptic curve cryptography is a type of asymmetric or public-key cryptography based on the discrete logarithm problem as expressed by addition and multiplication on the points of an elliptic curve.

Figure is an example of an elliptic curve, similar to that used by bitcoin. Bitcoin uses a specific elliptic curve and set of mathematical constants, as defined in a standard called secpk1 , established by the National Institute of Standards and Technology NIST. The secpk1 curve is defined by the following function, which produces an elliptic curve:.

Because this curve is defined over a finite field of prime order instead of over the real numbers, it looks like a pattern of dots scattered in two dimensions, which makes it difficult to visualize.

However, the math is identical as that of an elliptic curve over the real numbers. As an example, Figure shows the same elliptic curve over a much smaller finite field of prime order 17, showing a pattern of dots on a grid. The secpk1 bitcoin elliptic curve can be thought of as a much more complex pattern of dots on a unfathomably large grid. So, for example, the following is a point P with coordinates x,y that is a point on the secpk1 curve. You can check this yourself using Python:.

Geometrically, this third point P 3 is calculated by drawing a line between P 1 and P 2. This line will intersect the elliptic curve in exactly one additional place. This tangent will intersect the curve in exactly one new point.

You can use techniques from calculus to determine the slope of the tangent line. These techniques curiously work, even though we are restricting our interest to points on the curve with two integer coordinates! In some cases i. This shows how the point at infinity plays the role of 0. Now that we have defined addition, we can define multiplication in the standard way that extends addition.

Starting with a private key in the form of a randomly generated number k , we multiply it by a predetermined point on the curve called the generator point G to produce another point somewhere else on the curve, which is the corresponding public key K. The generator point is specified as part of the secpk1 standard and is always the same for all keys in bitcoin:.

Because the generator point is always the same for all bitcoin users, a private key k multiplied with G will always result in the same public key K. The relationship between k and K is fixed, but can only be calculated in one direction, from k to K.

A private key can be converted into a public key, but a public key cannot be converted back into a private key because the math only works one way. Implementing the elliptic curve multiplication, we take the private key k generated previously and multiply it with the generator point G to find the public key K:.

To visualize multiplication of a point with an integer, we will use the simpler elliptic curve over the real numbers—remember, the math is the same. Our goal is to find the multiple kG of the generator point G. That is the same as adding G to itself, k times in a row. In elliptic curves, adding a point to itself is the equivalent of drawing a tangent line on the point and finding where it intersects the curve again, then reflecting that point on the x-axis.

Figure shows the process for deriving G, 2G, 4G, as a geometric operation on the curve. Most bitcoin implementations use the OpenSSL cryptographic library to do the elliptic curve math. A bitcoin address is a string of digits and characters that can be shared with anyone who wants to send you money. Because paper checks do not need to specify an account, but rather use an abstract name as the recipient of funds, that makes paper checks very flexible as payment instruments.

Bitcoin transactions use a similar abstraction, the bitcoin address, to make them very flexible. The bitcoin address is derived from the public key through the use of one-way cryptographic hashing. Cryptographic hash functions are used extensively in bitcoin: in bitcoin addresses, in script addresses, and in the mining proof-of-work algorithm.

A bitcoin address is not the same as a public key. Bitcoin addresses are derived from a public key using a one-way function. Base58Check is also used in many other ways in bitcoin, whenever there is a need for a user to read and correctly transcribe a number, such as a bitcoin address, a private key, an encrypted key, or a script hash.

In the next section we will examine the mechanics of Base58Check encoding and decoding, and the resulting representations. Figure illustrates the conversion of a public key into a bitcoin address. In order to represent long numbers in a compact way, using fewer symbols, many computer systems use mixed-alphanumeric representations with a base or radix higher than For example, whereas the traditional decimal system uses the 10 numerals 0 through 9, the hexadecimal system uses 16, with the letters A through F as the six additional symbols.

A number represented in hexadecimal format is shorter than the equivalent decimal representation. Base is most commonly used to add binary attachments to email. Base58 is a text-based binary-encoding format developed for use in bitcoin and used in many other cryptocurrencies.

It offers a balance between compact representation, readability, and error detection and prevention. Base58 is a subset of Base64, using the upper- and lowercase letters and numbers, but omitting some characters that are frequently mistaken for one another and can appear identical when displayed in certain fonts.

Or, more simply, it is a set of lower and capital letters and numbers without the four 0, O, l, I just mentioned. To add extra security against typos or transcription errors, Base58Check is a Base58 encoding format, frequently used in bitcoin, which has a built-in error-checking code. The checksum is an additional four bytes added to the end of the data that is being encoded.

The checksum is derived from the hash of the encoded data and can therefore be used to detect and prevent transcription and typing errors. When presented with a Base58Check code, the decoding software will calculate the checksum of the data and compare it to the checksum included in the code. If the two do not match, that indicates that an error has been introduced and the Base58Check data is invalid. For example, this prevents a mistyped bitcoin address from being accepted by the wallet software as a valid destination, an error that would otherwise result in loss of funds.

For example, in the case of a bitcoin address the prefix is zero 0x00 in hex , whereas the prefix used when encoding a private key is 0x80 in hex. A list of common version prefixes is shown in Table From the resulting byte hash hash-of-a-hash , we take only the first four bytes. These four bytes serve as the error-checking code, or checksum.

The checksum is concatenated appended to the end. The result is composed of three items: a prefix, the data, and a checksum. This result is encoded using the Base58 alphabet described previously. Figure illustrates the Base58Check encoding process. In bitcoin, most of the data presented to the user is Base58Check-encoded to make it compact, easy to read, and easy to detect errors.

Ledger and Trezor are both well-known hardware wallet manufacturers. Wallet safety is essential, as cryptocurrencies are high-value targets for hackers. Some safeguards include encrypting the wallet with a strong password, using two-factor authentication for exchanges, and storing large amounts in an offline device.

Most modern wallets are generated from a twelve-word mnemonic seed, which can be used to restore the wallet if the device is lost or damaged. These words should be carefully stored in a safe place, since anyone who finds them will be able to steal your cryptocurrency. Disclaimer: Investing in cryptocurrencies and other Initial Coin Offerings "ICOs" is highly risky and speculative, and this article is not a recommendation by Investopedia or the writer to invest in cryptocurrencies or other ICOs.

Since each individual's situation is unique, a qualified professional should always be consulted before making any financial decisions. Investopedia makes no representations or warranties as to the accuracy or timeliness of the information contained herein.

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