Poker Tournament Clock

[Claudio Davey]

Iwant to gift a small amount of btc to my nieces and nephews. My idea was to laminate a small card with their wallet id and a mnemonic phrase; then transfer some btc to this wallet from my own accounts

You can click 'Generate' on this page (although I highly don't recommend using the online version, see below for more) to generate mnemonic phrases and use them. The site supports several languages, multiple currencies not just Bitcoin & more.

So I'm using the original bitcoin client.What if on a computer without internet (A) I generate a bitcoin address andthen use this address to receive a payment (by using an other computer with internet (B))

No, you don't need to be online when generating a new receiving address, as this is done locally by your bitcoin-core. You also don't need to be online to receive funds to these addresses, as long as you protect your wallet and keep your system free from malicious software you are the owner of these addresses and you will be able to check their balance as soon as you get online and let your wallet synchronize with the network.

It doesn't matter where the address is stored. As long as you communicate that address to someone somehow, they can issue a transaction to that address. However, the transaction must reach the network somehow in order for it to be confirmed into blockchain. Once that happens, everyone will be aware that your public address likely exists because they see that someone sent BTC to it.

supports several languages, multiple currencies not just Bitcoin & more.

A Bitcoin address is equivalent to a random number. The possible numbers this random number is picked from, is such a huge range of numbers (possibilities are as large as a 1 with 26 0's behind it!) that we can just pick any number in there and have almost the same odds of picking the same number someone else did. (If I tell you to pick a number between 1 and 10, you have a 1 in 10 chance of picking MY number.)

So I'm using the original bitcoin client.What if on a computer without internet (A) I generate a bitcoin address andthen use this address to receive a payment (by using an other computer with internet (B))

Meaning that, if I have a computer not connected to the internet, it can still pick a random number and create a human readable bitcoin address corresponding to the random number and be pretty sure that number / address has never been used before.

No, you don't need to be online when generating a new receiving address, as this is done locally by your bitcoin-core. You also don't need to be online to receive funds to these addresses, as long as you protect your wallet and keep your system free from malicious software you are the owner of these addresses and you will be able to check their balance as soon as you get online and let your wallet synchronize with the network.

This is a really great part of the system, because now I can send bitcoins to the address I just generated, knowing that I have the password (Private Key) for that address, but no one will steal that password, as long as my computer is not compromised (and it won't since it isn't connected to the internet.)

Also, every bitcoin address is permanent, since once it is included in the blockchain, it won't ever disappear out of it. The only thing you can lose is your private key. But the address will be included in the blockchain for as long as the blockchain will be run.

A Bitcoin address is equivalent to a random number. The possible numbers this random number is picked from, is such a huge range of numbers (possibilities are as large as a 1 with 26 0's behind it!) that we can just pick any number in there and have almost the same odds of picking the same number someone else did. (If I tell you to pick a number between 1 and 10, you have a 1 in 10 chance of picking MY number.)

With this generator it is possible to generate a random Bitcoin address. By clicking on the generate button based on the selection the Bitcoin public, wallet and private key then is generated. All keys can be copied to clipboard with the corresponding copy button. If you plan to use these valid Bitcoin addresses, for example for a wallet, please urgently keep this private key private.

Meaning that, if I have a computer not connected to the internet, it can still pick a random number and create a human readable bitcoin address corresponding to the random number and be pretty sure that number / address has never been used before.

Bitcoin is a cryptocurrency, a form of electronic cash. It is a decentralized digital currency without a central bank or single administrator that can be sent digitally from user-to-user on the peer-to-peer Bitcoin network without the need for intermediaries.

This is a really great part of the system, because now I can send bitcoins to the address I just generated, knowing that I have the password (Private Key) for that address, but no one will steal that password, as long as my computer is not compromised (and it won't since it isn't connected to the internet.)

A Bitcoin Address is an ID of 26-35 alphanumeric numbers, that represents a possible destination for an (incoming) Bitcoin payment for example to a Bitcoin Wallet. A Bitcoin wallet address, which is a hash of the corresponding public key, always starts either with number 1 or with the number 3.

Also, every bitcoin address is permanent, since once it is included in the blockchain, it won't ever disappear out of it. The only thing you can lose is your private key. But the address will be included in the blockchain for as long as the blockchain will be run.

With this generator it is possible to generate a random Bitcoin address. By clicking on the generate button based on the selection the Bitcoin public, wallet and private key then is generated. All keys can be copied to clipboard with the corresponding copy button. If you plan to use these valid Bitcoin addresses, for example for a wallet, please urgently keep this private key private.

Bitcoin is a cryptocurrency, a form of electronic cash. It is a decentralized digital currency without a central bank or single administrator that can be sent digitally from user-to-user on the peer-to-peer Bitcoin network without the need for intermediaries.

A Bitcoin Address is an ID of 26-35 alphanumeric numbers, that represents a possible destination for an (incoming) Bitcoin payment for example to a Bitcoin Wallet. A Bitcoin wallet address, which is a hash of the corresponding public key, always starts either with number 1 or with the number 3.

A Bitcoin address is a 160-bit hash of the public portion of a public/private ECDSA keypair. Using public-key cryptography, you can "sign" data with your private key and anyone who knows your public key can verify that the signature is valid.

A new keypair is generated for each receiving address (with newer HD wallets, this is done deterministically).The public key and their associated private keys (or the seed needed to generate them) are stored in the wallet data file.This is the only file users should need to backup.A "send" transaction to a specific Bitcoin address requires that the corresponding wallet knows the private key implementing it.This has the implication that if you create an address and receive coins to that address, then restore the wallet from an earlier backup, before the address was generated, then the coins received with that address are lost; this is not an issue for HD wallets where all addresses are generated from a single seed.Addresses are added to an address key pool prior to being used for receiving coins. If you lose your wallet entirely, all of your coins are lost and can never be recovered.

Bitcoin allows you to create as many addresses as you want, and use a new one for every transaction.There is no "master address": the "Your Bitcoin address" area in some wallet UIs has no special importance.It's only there for your convenience, and it should change automatically when used.

Bitcoin addresses contain a built-in check code, so it's generally not possible to send Bitcoins to a mistyped address. However, if the address is well-formed but no one owns it (or the owner lost their wallet.dat), any coins sent to that address will be lost forever.

Hash values and the checksum data are converted to an alpha-numeric representation using a custom scheme: the Base58Check encoding scheme. Under Base58Check, addresses can contain all alphanumeric characters except 0, O, I, and l. Mainnet P2PKH addresses start with 1, while P2SH addresses start with 3 (Bech32 addresses start with bc1 and do not use Base58Check encoding). Testnet addresses usually start with m or n. Mainnet addresses can be 25-34 characters in length, and testnet addresses can be 26-34 characters in length. Most addresses are 33 or 34 characters long.

Since Bitcoin addresses are basically random numbers, it is possible, although extremely unlikely, for two people to independently generate the same address. This is called a collision. If this happens, then both the original owner of the address and the colliding owner could spend money sent to that address. It would not be possible for the colliding person to spend the original owner's entire wallet (or vice versa).

The correct way to create a Bitcoin address is to use well tested, open source, peer reviewed wallet software. Manually handling keys has resulted in funds loss over and over again. Unlike other centralized systems losses in Bitcoin are usually unrecoverable.

Entropy values must be sourced from astrong source of randomness.This can be coin flipping, dice rolling, random noise data etc.Never use your own words, sentences from books, keyword smashing or anything random at a first glance. It will be not random enough for this application.

Storing entropy (i.e. keeping a deck of cards in a specific shuffled order) is unreliable compared to storing a seed phrase (mnemonic).Instead of storing entropy, store the mnemonic generated from the entropy. Preferably on some solid medium.

This random seed phrase generator uses arandom number generator that is cryptographically secure. If random cryptographic module is not available in your browser, the tool will show you a warning and the tool will not work. If that happens you may want to changea browser or use your own source of entropy.

Default number of iterations used in wallets is 2048. Increasing this number should make it more secure against brute force attacks, however you will have to store this value. To access your wallet with custom PBKDF2 you should use this script (or similar) to calculate your BIP39 seed phrase.

Randomly compute a seed phrase safely if you need to. Generate 12 or 24 words seed phrase, and other lengths.Check if your seed phrase is correct (you will receive a notification if a given word is not from the list.You can check all your individual addresses without a wallet, if you would need that.Compute your coins addresses plus private keys so you could retrieve funds manually by using Bip44 standard or other. Could be useful if you lose your wallet and are unable to get one.Create a new bip39/44 wallet to create a coin address and transfer your coins ASAP, then later input the seed in a wallet and restore. Could be useful in a bad case of a compromised wallet.Generate some truly random seed phrase with your own entropy source if you would like, for example, you can roll your own dice yourself.See how things work inside your hardware or software wallet. It is easy to see here that your seed phrase is also an instruction set for setting up addresses and private keys (i.e. Bip44). You can see how keys and addresses are computed from the seed.

The BIP39 protocol uses a list of 2048 carefully chosen english words. Although the lists in different languages exists, it is usually not recommended to use them because most wallets do support only english words. Read more about BIP39 standard.

The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.