== E-mProvement ==
E-mProvement est une start-up parisienne, fondée en 2013, qui propose aux entreprises des services d'accompagnement vers leurs adoption de Bitcoin, à savoir :
- des formations
- des missions d'étude
- des réalisations de prestations techniques

[[Fichier:Http://www.e-mprovement.com/images/e-mprovement/e-mprovement-logo-black.png|vignette|centré|Logo d'E-mProvement]]

== Voir aussi ==
[http://www.e-mprovement.com Site officiel]

E-mProvement

2015-07-04T15:48:05Z

AlbinCAUDERLIER : /* E-mProvement */

Portefeuille Papier

2015-07-04T15:42:35Z

AlbinCAUDERLIER : /* Voir également */

[[File:FirstBitcoinBills.jpg|thumb|right|200px|Casascius tenant les premiers portefeuilles papier]]

Dans un sens plus global, un "portefeuille papier" est un document contenant toutes les informations nécessaires pour générer n'importe quel nombre de clé privée Bitcoin, formant un portefeuille de clés. Mais, les gens utilisent souvent ce terme pour n'importe quelles façons de stocker ses bitcoins de manière hors-ligne sur un document physique. Cette seconde définitions inclus les codes récupérable ou des "clés papier". Une clé papier est une clé unique écrite sur un morceau de papier qui est utilisé plusieurs fois comme un portefeuille ( Ceci est d'ailleurs fortement [[address reuse|déconseiller]] ). Un code récupérable est une simple clé dont le but est d'être remplis et utiliser qu'une fois : C'est souvent utiliser pour des cadeaux ou dans le but de créer des billes ou pièces Bitcoin physique.

Stocker ses bitcoins sur un portefeuille papier n'est pas sécuriser SI vous ne suivez pas toutes les mesures de sécurité à prendre pendant la création ( voir ci-dessous ).

__TOC__

==Use cases==

===Tips and gifts===

By creating a keypair, one can store bitcoins on a physical medium to be left as a tip or a gift.
The recipient then sweeps the private key to their own wallet.

===Physical tokens===

A trusted provider can hide the private key inside a tamper-resistant token, and issue them as a form of bitcoins.
This requires those who accept it as payment to trust that when the provider produced the tokens, they loaded them with the correct amount of bitcoins, and that they have not been tampered with since then.
To redeem the bitcoin value, the token must be destroyed to access the private key.
Often a bitcoin address is embedded on the outside visible, but there is no guarantee (without destroying the token) that this matches the private key inside, or, even if it does, that the private key is not replicated on multiple tokens or saved by the producer.

===Portefeuille===

Proper paper wallets are often a very secure way of storing bitcoins, since they are not typically exposed to malware. They can also be easily stored securely in safes and safe deposit boxes. However, it may be more difficult to securely "backup" paper wallets, and due to the current sub-optimal software support, it may be easier to make a mistake that causes loss of bitcoins.

Sometimes people try to use single keys as true bitcoin wallets. However [[address reuse]] is very bad for privacy and security. Because of this, one is forced to choose between hazardous options:
* '''Use the key only once to receive, and only once to send the full amount.''' This requires the user to know the full amount he wants to store in advance, and often leads to the next situation:
* '''Create multiple keys.''' By using more than one key, the user can receive more than once using a different address each time, including using new addresses for change. This is very complicated, and makes it easy to accidentally reuse addresses, produce the wrong change/fee combination, lose some keys, spend hours searching for the right key, etc. Not even skilled bitcoin experts are comfortable managing their own keys manually like this.

Therefore, it is highly recommended that you use proper paper wallets which allow you to generate an infinite number of addresses from a single seed.

==Encoding/formatting==

[[File:BitcoinPaperWallet-sample.jpg|thumb|right|300px|Paper keypair with private key secured beneath folds]]
[[File:PaperWallets-offlineaddress-com.png|200px|thumb|right|Paper keypair]]
Proper, multi-key paper wallets usually take the form of a multi-word [[Deterministic wallet | HD wallet]] seed mnemonic. The list of several words corresponds to some binary data that is used to generate all of the addresses. Words are used to make it easier to avoid and correct errors. Trying to memorize an entire seed mnemonic is very difficult and is generally not recommended.

A single key (for use in insecure single-key paper wallets or redeemable codes) can be represented in several formats, but typically the Wallet Import Format (WIF) is used, since keys represented that way are very short (51 characters) and thus easy to re-enter when importing or "sweeping" it for withdrawal.

==Creation of a paper wallet==

===Generation of secure keys===

The private seed is used to prove your right to spend the bitcoins transferred to the paper wallet, and as such should be kept hidden and secret.
If the private seed on a paper wallet is exposed (for example in a photograph) then the wallet may be used by anyone who sees it.
To guard against accidental revelation, the private key displayed on the paper wallet may be encrypted or split into several different parts (for example using [https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing Shamir's secret sharing scheme]).
At the very least, the private key should be well hidden e.g. by folding the wallet in half and sealing it shut.

Currently, at least [[Armory]] and [[Electrum]] support generating mnemonic codes for their wallets, which can be written down or printed to make a multi-key paper wallet.

Several tools exist for producing single keys, including [[Bitcoin Address Utility]], [[vanitygen]], and [[Cwallet]]. Again, using single keys for anything except one-time ''transfers'' of bitcoins is strongly [[address reuse|discouraged]].

===Web-based key generators===

Some websites feature free open-source client-side keypair/wallet generators written in JavaScript.
Keypairs/wallets generated by JavaScript or using websites are inherently weak and insecure, and unless the code of the website is audited every time it is used, it may leak the generated keys back to the server—especially if un-audited Javascript is downloaded and run locally.
Even with careful code auditing, browser plugins or other websites may compromise the environment.

===Recommendations===
* Disconnecting from the Internet guarantees that that the paper wallet generator is truly self-contained and isn't transmitting your keys online.
* Verifying the integrity of the code (and the trustworthiness of the author) is important to make sure a hacker hasn't modified the download so that it generates predictable seeds instead of truly random ones.
* Remember, spyware and viruses often attempt to monitor your computer activities so that their authors can steal from you. They are interested in passwords to online accounts, and anything of value. Bitcoin wallets are something of value that have already been targeted by malware. If your computer is infected with spyware or viruses - even if there are no symptoms, or your antivirus isn't reporting anything - then anything you type, view, or save on your computer, could potentially be stolen by someone remotely controlling your computer. Your private seed can then be intercepted while you enter it, so only enter a Bitcoin private seed into your computer when you are certain it is secure (such as a fresh boot of a LiveCD).
* The wallet should never be saved to a computer hard drive or sent via email or other network connections. You should also never scan/type your key into your computer, except at the moment you are using it.
* If possible, the wallet should be kept hidden, for example by using BIP38 encryption (single keys only), and/or by folding the paper to hide the private key so that a photograph or photocopy of it will not reveal or replicate the private key.
* A web-based generator should not be used.
* A generator should use an appropriate source of random numbers (entropy). This means that the generated keys aren't predictable. If the addresses come from a predictable or partially-predictable patterns like pseudorandom numbers <ref>[https://en.wikipedia.org/wiki/Pseudorandomness#Cryptography Pseudorandomness] '' is not enough for strong cryptography''</ref>, someone else who can predict the pattern can steal the balance. Randomness should NEVER be human generated, as the human brain is incapable of secure entropy.
* Remember that unlike wallets (paper or otherwise), a single paper key is only good to receive a single payment, and must be redeemed in its entirety.

===Printer Security===

Some advanced printers have internal storage (even hard drives) that preserve copies of printouts. This is a risk if someone gets access to your printer, or if you dispose of your printer. There is also the possibility that a smart enough printer can be hacked. (Consider [http://en.wikipedia.org/wiki/Stuxnet StuxNet] which was able to rewrite the firmware of non-computer devices indirectly connected to the Internet) If this concerns you, use a "dumb" printer, and never let your printer have access to the Internet or to an Internet-connected computer.

==Redeeming Keys and Withdrawing Funds==

This section applies only to single-key paper "wallets".

Paper keys, when used as wallets, are very different from wallets such as Bitcoin Core in that there is only one address in a paper key rather than a hundred or more online keys that are managed with full software assistance from Bitcoin Core.

There are various methods for copying the private key data to other wallets.
* bitcoind supports an "importprivkey" RPC method for this purpose.
* Bitcoin-Qt's debug console can also be used in a similar way (see also [[How to import private keys in Bitcoin Core 0.7+]]).
* [[BlockChain.info]] and [[Armory]] can also import them directly into wallets.
* [http://MyCelium.com/download Mycelium] is a Android mobile wallet with an easy to use "cold storage" spending function. It is also available via Android and iTunes playstore. The iTunes version may not yet support cold storage spending.

Note that importing a private key that may be compromised can result in the entire wallet becoming insecure. For this reason, sweeping (or sending the entire amount to a fresh address) is generally recommended over plain importing.

==References==
<references />

== Voir également ==

* [[Clé privée]]

* [[Sécuriser_votre_portefeuille]]

* [[Comment importer des clés privées]]

* [https://blockchain.info/wallet/paper-tutorial Blockchain.info tutorial] on comment générer un porte-feuille papier.

* [[Casascius physical bitcoins]]

[[Category:Securité]]

[[es:Monedero de papel]]

Portefeuille Papier

2015-07-04T15:41:50Z

AlbinCAUDERLIER : /* Voir également */

[[File:FirstBitcoinBills.jpg|thumb|right|200px|Casascius tenant les premiers portefeuilles papier]]

Dans un sens plus global, un "portefeuille papier" est un document contenant toutes les informations nécessaires pour générer n'importe quel nombre de clé privée Bitcoin, formant un portefeuille de clés. Mais, les gens utilisent souvent ce terme pour n'importe quelles façons de stocker ses bitcoins de manière hors-ligne sur un document physique. Cette seconde définitions inclus les codes récupérable ou des "clés papier". Une clé papier est une clé unique écrite sur un morceau de papier qui est utilisé plusieurs fois comme un portefeuille ( Ceci est d'ailleurs fortement [[address reuse|déconseiller]] ). Un code récupérable est une simple clé dont le but est d'être remplis et utiliser qu'une fois : C'est souvent utiliser pour des cadeaux ou dans le but de créer des billes ou pièces Bitcoin physique.

Stocker ses bitcoins sur un portefeuille papier n'est pas sécuriser SI vous ne suivez pas toutes les mesures de sécurité à prendre pendant la création ( voir ci-dessous ).

__TOC__

==Use cases==

===Tips and gifts===

By creating a keypair, one can store bitcoins on a physical medium to be left as a tip or a gift.
The recipient then sweeps the private key to their own wallet.

===Physical tokens===

A trusted provider can hide the private key inside a tamper-resistant token, and issue them as a form of bitcoins.
This requires those who accept it as payment to trust that when the provider produced the tokens, they loaded them with the correct amount of bitcoins, and that they have not been tampered with since then.
To redeem the bitcoin value, the token must be destroyed to access the private key.
Often a bitcoin address is embedded on the outside visible, but there is no guarantee (without destroying the token) that this matches the private key inside, or, even if it does, that the private key is not replicated on multiple tokens or saved by the producer.

===Portefeuille===

Proper paper wallets are often a very secure way of storing bitcoins, since they are not typically exposed to malware. They can also be easily stored securely in safes and safe deposit boxes. However, it may be more difficult to securely "backup" paper wallets, and due to the current sub-optimal software support, it may be easier to make a mistake that causes loss of bitcoins.

Sometimes people try to use single keys as true bitcoin wallets. However [[address reuse]] is very bad for privacy and security. Because of this, one is forced to choose between hazardous options:
* '''Use the key only once to receive, and only once to send the full amount.''' This requires the user to know the full amount he wants to store in advance, and often leads to the next situation:
* '''Create multiple keys.''' By using more than one key, the user can receive more than once using a different address each time, including using new addresses for change. This is very complicated, and makes it easy to accidentally reuse addresses, produce the wrong change/fee combination, lose some keys, spend hours searching for the right key, etc. Not even skilled bitcoin experts are comfortable managing their own keys manually like this.

Therefore, it is highly recommended that you use proper paper wallets which allow you to generate an infinite number of addresses from a single seed.

==Encoding/formatting==

[[File:BitcoinPaperWallet-sample.jpg|thumb|right|300px|Paper keypair with private key secured beneath folds]]
[[File:PaperWallets-offlineaddress-com.png|200px|thumb|right|Paper keypair]]
Proper, multi-key paper wallets usually take the form of a multi-word [[Deterministic wallet | HD wallet]] seed mnemonic. The list of several words corresponds to some binary data that is used to generate all of the addresses. Words are used to make it easier to avoid and correct errors. Trying to memorize an entire seed mnemonic is very difficult and is generally not recommended.

A single key (for use in insecure single-key paper wallets or redeemable codes) can be represented in several formats, but typically the Wallet Import Format (WIF) is used, since keys represented that way are very short (51 characters) and thus easy to re-enter when importing or "sweeping" it for withdrawal.

==Creation of a paper wallet==

===Generation of secure keys===

The private seed is used to prove your right to spend the bitcoins transferred to the paper wallet, and as such should be kept hidden and secret.
If the private seed on a paper wallet is exposed (for example in a photograph) then the wallet may be used by anyone who sees it.
To guard against accidental revelation, the private key displayed on the paper wallet may be encrypted or split into several different parts (for example using [https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing Shamir's secret sharing scheme]).
At the very least, the private key should be well hidden e.g. by folding the wallet in half and sealing it shut.

Currently, at least [[Armory]] and [[Electrum]] support generating mnemonic codes for their wallets, which can be written down or printed to make a multi-key paper wallet.

Several tools exist for producing single keys, including [[Bitcoin Address Utility]], [[vanitygen]], and [[Cwallet]]. Again, using single keys for anything except one-time ''transfers'' of bitcoins is strongly [[address reuse|discouraged]].

===Web-based key generators===

Some websites feature free open-source client-side keypair/wallet generators written in JavaScript.
Keypairs/wallets generated by JavaScript or using websites are inherently weak and insecure, and unless the code of the website is audited every time it is used, it may leak the generated keys back to the server—especially if un-audited Javascript is downloaded and run locally.
Even with careful code auditing, browser plugins or other websites may compromise the environment.

===Recommendations===
* Disconnecting from the Internet guarantees that that the paper wallet generator is truly self-contained and isn't transmitting your keys online.
* Verifying the integrity of the code (and the trustworthiness of the author) is important to make sure a hacker hasn't modified the download so that it generates predictable seeds instead of truly random ones.
* Remember, spyware and viruses often attempt to monitor your computer activities so that their authors can steal from you. They are interested in passwords to online accounts, and anything of value. Bitcoin wallets are something of value that have already been targeted by malware. If your computer is infected with spyware or viruses - even if there are no symptoms, or your antivirus isn't reporting anything - then anything you type, view, or save on your computer, could potentially be stolen by someone remotely controlling your computer. Your private seed can then be intercepted while you enter it, so only enter a Bitcoin private seed into your computer when you are certain it is secure (such as a fresh boot of a LiveCD).
* The wallet should never be saved to a computer hard drive or sent via email or other network connections. You should also never scan/type your key into your computer, except at the moment you are using it.
* If possible, the wallet should be kept hidden, for example by using BIP38 encryption (single keys only), and/or by folding the paper to hide the private key so that a photograph or photocopy of it will not reveal or replicate the private key.
* A web-based generator should not be used.
* A generator should use an appropriate source of random numbers (entropy). This means that the generated keys aren't predictable. If the addresses come from a predictable or partially-predictable patterns like pseudorandom numbers <ref>[https://en.wikipedia.org/wiki/Pseudorandomness#Cryptography Pseudorandomness] '' is not enough for strong cryptography''</ref>, someone else who can predict the pattern can steal the balance. Randomness should NEVER be human generated, as the human brain is incapable of secure entropy.
* Remember that unlike wallets (paper or otherwise), a single paper key is only good to receive a single payment, and must be redeemed in its entirety.

===Printer Security===

Some advanced printers have internal storage (even hard drives) that preserve copies of printouts. This is a risk if someone gets access to your printer, or if you dispose of your printer. There is also the possibility that a smart enough printer can be hacked. (Consider [http://en.wikipedia.org/wiki/Stuxnet StuxNet] which was able to rewrite the firmware of non-computer devices indirectly connected to the Internet) If this concerns you, use a "dumb" printer, and never let your printer have access to the Internet or to an Internet-connected computer.

==Redeeming Keys and Withdrawing Funds==

This section applies only to single-key paper "wallets".

Paper keys, when used as wallets, are very different from wallets such as Bitcoin Core in that there is only one address in a paper key rather than a hundred or more online keys that are managed with full software assistance from Bitcoin Core.

There are various methods for copying the private key data to other wallets.
* bitcoind supports an "importprivkey" RPC method for this purpose.
* Bitcoin-Qt's debug console can also be used in a similar way (see also [[How to import private keys in Bitcoin Core 0.7+]]).
* [[BlockChain.info]] and [[Armory]] can also import them directly into wallets.
* [http://MyCelium.com/download Mycelium] is a Android mobile wallet with an easy to use "cold storage" spending function. It is also available via Android and iTunes playstore. The iTunes version may not yet support cold storage spending.

Note that importing a private key that may be compromised can result in the entire wallet becoming insecure. For this reason, sweeping (or sending the entire amount to a fresh address) is generally recommended over plain importing.

==References==
<references />

== Voir également ==

* [[Clé privée]]

* [[Sécuriser_votre_portefeuille Wallets papiers]]

* [[Comment importer des clés privées]]

* [https://blockchain.info/wallet/paper-tutorial Blockchain.info tutorial] on comment générer un porte-feuille papier.

* [[Casascius physical bitcoins]]

[[Category:Securité]]

[[es:Monedero de papel]]

Portefeuille Papier

2015-07-04T15:40:13Z

AlbinCAUDERLIER : /* Voir également */

[[File:FirstBitcoinBills.jpg|thumb|right|200px|Casascius tenant les premiers portefeuilles papier]]

Dans un sens plus global, un "portefeuille papier" est un document contenant toutes les informations nécessaires pour générer n'importe quel nombre de clé privée Bitcoin, formant un portefeuille de clés. Mais, les gens utilisent souvent ce terme pour n'importe quelles façons de stocker ses bitcoins de manière hors-ligne sur un document physique. Cette seconde définitions inclus les codes récupérable ou des "clés papier". Une clé papier est une clé unique écrite sur un morceau de papier qui est utilisé plusieurs fois comme un portefeuille ( Ceci est d'ailleurs fortement [[address reuse|déconseiller]] ). Un code récupérable est une simple clé dont le but est d'être remplis et utiliser qu'une fois : C'est souvent utiliser pour des cadeaux ou dans le but de créer des billes ou pièces Bitcoin physique.

Stocker ses bitcoins sur un portefeuille papier n'est pas sécuriser SI vous ne suivez pas toutes les mesures de sécurité à prendre pendant la création ( voir ci-dessous ).

__TOC__

==Use cases==

===Tips and gifts===

By creating a keypair, one can store bitcoins on a physical medium to be left as a tip or a gift.
The recipient then sweeps the private key to their own wallet.

===Physical tokens===

A trusted provider can hide the private key inside a tamper-resistant token, and issue them as a form of bitcoins.
This requires those who accept it as payment to trust that when the provider produced the tokens, they loaded them with the correct amount of bitcoins, and that they have not been tampered with since then.
To redeem the bitcoin value, the token must be destroyed to access the private key.
Often a bitcoin address is embedded on the outside visible, but there is no guarantee (without destroying the token) that this matches the private key inside, or, even if it does, that the private key is not replicated on multiple tokens or saved by the producer.

===Portefeuille===

Proper paper wallets are often a very secure way of storing bitcoins, since they are not typically exposed to malware. They can also be easily stored securely in safes and safe deposit boxes. However, it may be more difficult to securely "backup" paper wallets, and due to the current sub-optimal software support, it may be easier to make a mistake that causes loss of bitcoins.

Sometimes people try to use single keys as true bitcoin wallets. However [[address reuse]] is very bad for privacy and security. Because of this, one is forced to choose between hazardous options:
* '''Use the key only once to receive, and only once to send the full amount.''' This requires the user to know the full amount he wants to store in advance, and often leads to the next situation:
* '''Create multiple keys.''' By using more than one key, the user can receive more than once using a different address each time, including using new addresses for change. This is very complicated, and makes it easy to accidentally reuse addresses, produce the wrong change/fee combination, lose some keys, spend hours searching for the right key, etc. Not even skilled bitcoin experts are comfortable managing their own keys manually like this.

Therefore, it is highly recommended that you use proper paper wallets which allow you to generate an infinite number of addresses from a single seed.

==Encoding/formatting==

[[File:BitcoinPaperWallet-sample.jpg|thumb|right|300px|Paper keypair with private key secured beneath folds]]
[[File:PaperWallets-offlineaddress-com.png|200px|thumb|right|Paper keypair]]
Proper, multi-key paper wallets usually take the form of a multi-word [[Deterministic wallet | HD wallet]] seed mnemonic. The list of several words corresponds to some binary data that is used to generate all of the addresses. Words are used to make it easier to avoid and correct errors. Trying to memorize an entire seed mnemonic is very difficult and is generally not recommended.

A single key (for use in insecure single-key paper wallets or redeemable codes) can be represented in several formats, but typically the Wallet Import Format (WIF) is used, since keys represented that way are very short (51 characters) and thus easy to re-enter when importing or "sweeping" it for withdrawal.

==Creation of a paper wallet==

===Generation of secure keys===

The private seed is used to prove your right to spend the bitcoins transferred to the paper wallet, and as such should be kept hidden and secret.
If the private seed on a paper wallet is exposed (for example in a photograph) then the wallet may be used by anyone who sees it.
To guard against accidental revelation, the private key displayed on the paper wallet may be encrypted or split into several different parts (for example using [https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing Shamir's secret sharing scheme]).
At the very least, the private key should be well hidden e.g. by folding the wallet in half and sealing it shut.

Currently, at least [[Armory]] and [[Electrum]] support generating mnemonic codes for their wallets, which can be written down or printed to make a multi-key paper wallet.

Several tools exist for producing single keys, including [[Bitcoin Address Utility]], [[vanitygen]], and [[Cwallet]]. Again, using single keys for anything except one-time ''transfers'' of bitcoins is strongly [[address reuse|discouraged]].

===Web-based key generators===

Some websites feature free open-source client-side keypair/wallet generators written in JavaScript.
Keypairs/wallets generated by JavaScript or using websites are inherently weak and insecure, and unless the code of the website is audited every time it is used, it may leak the generated keys back to the server—especially if un-audited Javascript is downloaded and run locally.
Even with careful code auditing, browser plugins or other websites may compromise the environment.

===Recommendations===
* Disconnecting from the Internet guarantees that that the paper wallet generator is truly self-contained and isn't transmitting your keys online.
* Verifying the integrity of the code (and the trustworthiness of the author) is important to make sure a hacker hasn't modified the download so that it generates predictable seeds instead of truly random ones.
* Remember, spyware and viruses often attempt to monitor your computer activities so that their authors can steal from you. They are interested in passwords to online accounts, and anything of value. Bitcoin wallets are something of value that have already been targeted by malware. If your computer is infected with spyware or viruses - even if there are no symptoms, or your antivirus isn't reporting anything - then anything you type, view, or save on your computer, could potentially be stolen by someone remotely controlling your computer. Your private seed can then be intercepted while you enter it, so only enter a Bitcoin private seed into your computer when you are certain it is secure (such as a fresh boot of a LiveCD).
* The wallet should never be saved to a computer hard drive or sent via email or other network connections. You should also never scan/type your key into your computer, except at the moment you are using it.
* If possible, the wallet should be kept hidden, for example by using BIP38 encryption (single keys only), and/or by folding the paper to hide the private key so that a photograph or photocopy of it will not reveal or replicate the private key.
* A web-based generator should not be used.
* A generator should use an appropriate source of random numbers (entropy). This means that the generated keys aren't predictable. If the addresses come from a predictable or partially-predictable patterns like pseudorandom numbers <ref>[https://en.wikipedia.org/wiki/Pseudorandomness#Cryptography Pseudorandomness] '' is not enough for strong cryptography''</ref>, someone else who can predict the pattern can steal the balance. Randomness should NEVER be human generated, as the human brain is incapable of secure entropy.
* Remember that unlike wallets (paper or otherwise), a single paper key is only good to receive a single payment, and must be redeemed in its entirety.

===Printer Security===

Some advanced printers have internal storage (even hard drives) that preserve copies of printouts. This is a risk if someone gets access to your printer, or if you dispose of your printer. There is also the possibility that a smart enough printer can be hacked. (Consider [http://en.wikipedia.org/wiki/Stuxnet StuxNet] which was able to rewrite the firmware of non-computer devices indirectly connected to the Internet) If this concerns you, use a "dumb" printer, and never let your printer have access to the Internet or to an Internet-connected computer.

==Redeeming Keys and Withdrawing Funds==

This section applies only to single-key paper "wallets".

Paper keys, when used as wallets, are very different from wallets such as Bitcoin Core in that there is only one address in a paper key rather than a hundred or more online keys that are managed with full software assistance from Bitcoin Core.

There are various methods for copying the private key data to other wallets.
* bitcoind supports an "importprivkey" RPC method for this purpose.
* Bitcoin-Qt's debug console can also be used in a similar way (see also [[How to import private keys in Bitcoin Core 0.7+]]).
* [[BlockChain.info]] and [[Armory]] can also import them directly into wallets.
* [http://MyCelium.com/download Mycelium] is a Android mobile wallet with an easy to use "cold storage" spending function. It is also available via Android and iTunes playstore. The iTunes version may not yet support cold storage spending.

Note that importing a private key that may be compromised can result in the entire wallet becoming insecure. For this reason, sweeping (or sending the entire amount to a fresh address) is generally recommended over plain importing.

==References==
<references />

== Voir également ==

* [[Clé privée]]

* [[Sécuriser votre porte-feuille#Wallets papiers]]

* [[Comment importer des clés privées]]

* [https://blockchain.info/wallet/paper-tutorial Blockchain.info tutorial] on comment générer un porte-feuille papier.

* [[Casascius physical bitcoins]]

[[Category:Securité]]

[[es:Monedero de papel]]

Sécuriser votre portefeuille

2015-07-04T15:38:01Z

AlbinCAUDERLIER : /* Voir aussi */

== Introduction ==

A moins que vous utilisiez un portefeuille physique il est fortement conseiller de lire cette page.

La sécurité d'un portefeuille à deux objectifs :

# Protéger votre portefeuille d'une perte.
# Protéger votre portefeuille d'un vol.

Dans le cas où votre portefeuille n'a pas été correctement protéger ( ex : L'avoir mis en ligne avec un mot de passe facile à trouver ) :
# Vous devez créer un nouveau portefeuille en utilisant une protection approprier sur le long-terme.
Pour un petit résumé voir aussi : [[Sécurité du portefeuille : Les choses à faire et à ne pas faire]]

== Portefeuille Papier ==

Page principal : [[Portefeuille Papier]]

Les [[Portefeuille Papier|portefeuilles papier]] peuvent être utiliser pour stocker des bitcoins hors-ligne dans un format non digital. Utilisez des portefeuilles papier générés de manière sécuriser permet de faire baisser drastiquement les chances de se faire voler ses bitcoins par des pirates ou des virus informatique. Un portefeuille papier n'est rien d'autre qu'un enregistrement physique de la clé privée de votre portefeuille Bitcoin.

== Portefeuille Physique ==

Les portefeuilles physique sont une avancée majeur dans la sécurité et l'accessibilité des portefeuilles Bitcoin.

Voir la page sur les portefeuilles physique pour plus d'informations sur les types de portefeuilles physique disponible sur le marché.

== Importance des mises à jour de sécurité ==

Aucun logiciel informatique n'est parfait, et de temps en temps certaines vulnérabilités peuvent être trouver dans votre client Bitcoin. C'est pour cela qu'il faut bien faire attention à toujours effectuer les mises à jours de son client Bitcoin, encore plus quand une vulnérabilité est découverte. Nous maintenant une liste de vulnérabilités connues sur le wiki - vous pouvez voir cette page pour des mises à jours. Noté que vous n'avez pas forcément besoin d'avoir la dernière version de votre client Bitcoin : Certains clients, comme le très célèbre et populaire Bitcoin Core ( Anciennement Bitcoin-Qt ), possèdent des anciennes versions avec uniquement des mises à jours de sécurité.

== Sécuriser le portefeuille Bitcoin Core ou bitcoind ==

Bitcoin transactions send Bitcoins to a specific public key. A Bitcoin address is an encoded hash of a public key. In order to use received Bitcoins, you need to have the private key matching the public key you received with. This is sort of like a super long password associated with an account (the account is the public key). Your Bitcoin wallet contains all of the private keys necessary for spending your received transactions. If you delete your wallet without a backup, then you no longer have the authorization information necessary to claim your coins, and the coins associated with those keys are lost forever.

The wallet contains a pool of queued keys. By default there are 100 keys in the key pool. The size of the pool is configurable using the "-keypool" command line argument. When you need an address for whatever reason (send, “new address”, generation, etc.), the key is not actually generated freshly, but taken from this pool. A brand new address is generated to fill the pool back to 100. So when a backup is first created, it has all of your old keys plus 100 unused keys. After sending a transaction, it has 99 unused keys. After a total of 100 new-key actions, you will start using keys that are not in your backup. Since the backup does not have the private keys necessary for authorizing spends of these coins, restoring from the old backup will cause you to lose Bitcoins.

Creating a new address generates a new pair of public and private keys, which are added to your wallet. Each keypair is mostly random numbers, so they cannot be known prior to generation. If you backup your wallet and then create more than 100 new addresses, the keypair associated with the newest addresses will not be in the old wallet because the new keypairs are only known after creating them. Any coins received at these addresses will be lost if you restore from the backup.

The situation is made somewhat more confusing because the receiving addresses shown in the UI are not the only keys in your wallet. Each Bitcoin generation is given a new public key, and, more importantly, each sent transaction also sends some number of Bitcoins back to yourself at a new key. When sending Bitcoins to anyone, you generate a new keypair for yourself and simultaneously send Bitcoins to your new public key and the actual recipient's public key. This is an anonymity feature – it makes tracking Bitcoin transactions much more difficult.

So if you create a backup, and then do more than 100 things that cause a new key to be used, and then restore from the backup, some Bitcoins will be lost. Bitcoin has not deleted any keys (keys are never deleted) – it has created a new key that is not in your old backup and then sent Bitcoins to it. A backup is therefore recommended roughly every 50 transactions (or address creations) just to be safe.

== Créer un nouveau portefeuille Bitcoin Core ou bitcoind ==

== Créer un espace de travail sécurisé ==

=== Linux ( Debian ) ===

==== Tout stocker dans un dossier crypté ====

==== Sécurisé l'ensemble du répertoire principal de l'utilisateur ====

=== Mac ===

=== Windows ===

=== Solution général ===

==== Fiabilité du mot de passe ====

===== Choisir un mot de passe fort =====

== Sauvegarder son portefeuille ==

== Supprimer les portefeuilles avec du texte en clair ==

== Portefeuille en ligne et mobile ==

== Voir aussi ==

[http://fr.btcna.me btcname : Alias d'adresse publique Bitcoin]

2015-06-12T09:22:38Z

AlbinCAUDERLIER :

Eclairons quelques points communéments incompris de Bitcoin.

== Bitcoin est comme toutes les autres monnaies virtuelles; Rien de nouveau ==

Presque toutes les autres monnaies digitales ont un contrôle centralisé. Cela signifie que :
* Elles peuvent être émises sur la simple décision de ceux qui la contrôle
* Elle peut être détruite en attaquant le point central de contrôle
* Des règles arbitraires peuvent être imposées aux utilisateurs par les contrôleurs

En étant décentralisé, Bitcoin résout tout ces problèmes.

== Bitcoins ne résout aucun problème que les monnaies locales et/ou l'or ne résolve(nt) ==

A la différence de l'or, les bitcoins sont:
* Facile à transférer
* Facile à sécuriser
* Facile à vérifier
* Facile à décomposer (granulate)

A la différence des monnaies locales, les bitcoins sont:
* A l'[[Controlled_Currency_Supply|émission]] limitée et prédite
* Pas contrôlé par une autorité centrale (tel que [http://en.wikipedia.org/wiki/Federal_Reserve la Réserve Fédérale des Etats-Unis])
* Pas fondés sur une dette

A la différence des systèmes de monnaies électroniques étatiques, les bitcoins sont:
* Potentially anonymous
* Freeze-proof
* Faster to transfer
* Cheaper to transfer

== Bitcoin est fondé sur de la puissance de calcul ==

It is not correct to say that Bitcoin is "backed by" processing power. A currency being "backed" means that it is pegged to something else via a central party at a certain exchange rate yet you cannot exchange bitcoins for the computing power that was used to create them. Bitcoin is in this sense not backed by anything. It is a currency in its own right. Just as gold is not backed by anything, the same applies to Bitcoin.

The Bitcoin currency is ''created'' via processing power, and the integrity of the block chain is ''protected'' by the existence of a network of powerful computing nodes from certain [[Weaknesses#Attacker_has_a_lot_of_computing_power|attacks]].

== Bitcoins sont vains car ils ne sont fondés sur rien ==

One could argue that gold isn't backed by anything either. Bitcoins have properties resulting from the system's design that allows them to be subjectively valued by individuals. This valuation is demonstrated when individuals freely exchange for or with bitcoins. Please refer to the [http://en.wikipedia.org/wiki/Subjective_theory_of_value Subjective Theory of Value].

See also: the "[[#Bitcoin_is_backed_by_processing_power|Bitcoin is backed by processing power]]" myth.

== La valeur des bitcoins sont fondés sur la quantité d'électricité et de traitement qu'il faut pour les miner ==

This statement is an attempt to apply to Bitcoin the [http://en.wikipedia.org/wiki/Labor_theory_of_value labor theory of value], which is generally accepted as false. Just because something takes X resources to create does not mean that the resulting product will be worth X. It can be worth more, or less, depending on the utility thereof to its users.

In fact the causality is the reverse of that (this applies to the labor theory of value in general). The cost to mine bitcoins is based on how much they are worth. If bitcoins go up in value, more people will mine (because [[Mining|mining]] is profitable), thus [[difficulty]] will go up, thus the cost of mining will go up. The inverse happens if bitcoins go down in value. These effects balance out to cause mining to always cost an amount proportional to the value of bitcoins it produces<ref>[https://www.bitcoinmining.com Bitcoin Mining]</ref>.

== Bitcoins have no intrinsic value (unlike some other things) ==

This is simply not true. Each bitcoin gives the holder the ability to embed a large number of short in-transaction messages in a globally distributed and timestamped permanent data store, namely the bitcoin blockchain. There is no other similar datastore which is so widely distributed. There is a tradeoff between the exact number of messages and how quickly they can be embedded. But as of December 2013, it's fair to say that one bitcoin allows around 1000 such messages to be embedded, each within about 10 minutes of being sent, since a fee of 0.001 BTC is enough to get transactions confirmed quickly. This message embedding certainly has intrinsic value since it can be used to prove ownership of a document at a certain time, by including a one-way hash of that document in a transaction. Considering that electronic notarization services charge something like $10/document, this would give an intrinsic value of around $10,000 per bitcoin.

While some other tangible commodities do have intrinsic value, that value is generally much less than its trading price. Consider for example that gold, if it were not used as an inflation-proof store of value, but rather only for its industrial uses, would certainly not be worth what it is today, since the industrial requirements for gold are far smaller than the available supply thereof.

In any event, while historically intrinsic value, as well as other attributes like divisibility, fungibility, scarcity, durability, helped establish certain commodities as mediums of exchange, it is certainly not a prerequisite. While bitcoins are accused of lacking 'intrinsic value' in this sense, they make up for it in spades by possessing the other qualities necessary to make it a good medium of exchange, equal to or better than [http://en.wikipedia.org/wiki/Commodity_money commodity money].

Another way to think about this is to consider the value of bitcoin the global network, rather than each bitcoin in isolation. The value of an individual telephone is derived from the network it is connected to. If there was no phone network, a telephone would be useless. Similarly the value of an individual bitcoin derives from the global network of bitcoin-enabled merchants, exchanges, wallets, etc... Just like a phone is necessary to transmit vocal information through the network, a bitcoin is necessary to transmit economic information through the network.

Value is ultimately determined by what people are willing to trade for - by supply and demand.

== Bitcoins are illegal because they're not legal tender ==
In March 2013, the U.S. [http://en.wikipedia.org/wiki/Financial_Crimes_Enforcement_Network Financial Crimes Enforcement Network] issues a new set of guidelines on "de-centralized virtual currency", clearly targeting Bitcoin. Under the new guidelines, "a user of virtual currency is not a Money Services Businesses (MSB) under FinCEN's regulations and therefore is not subject to MSB registration, reporting, and record keeping regulations." <ref>[http://arstechnica.com/tech-policy/2013/03/us-regulator-bitcoin-exchanges-must-comply-with-money-laundering-laws/ US regulator: Bitcoin exchanges must comply with money-laundering laws | Ars Technica]</ref> [[Mining|Miners]], when mining bitcoins for their own personal use, aren't required to register as a MSB or Money Transmitter. <ref>[http://fincen.gov/news_room/rp/rulings/html/FIN-2014-R001.html Application of FinCEN’s Regulations to Virtual Currency Mining Operations | Fincen]</ref>

In general, there are a [http://en.wikipedia.org/wiki/Local_currency number of currencies] in existence that are not official government-backed currencies. A currency is, after all, nothing more than a convenient unit of account. While national laws may vary from country to country, and you should certainly check the laws of your jurisdiction, in general trading in any commodity, including digital currency like Bitcoin, [http://en.wikipedia.org/wiki/BerkShares BerkShares], game currencies like WoW gold, or Linden dollars, is not illegal.

== Bitcoin is a form of domestic terrorism because it only harms the economic stability of the USA and its currency ==

According to [http://en.wikipedia.org/wiki/Definitions_of_terrorism#United_States the definition of terrorism in the United States], you need to do violent activities to be considered a terrorist for legal purposes. Recent off-the-cuff remarks by politicians have no basis in law or fact.

Also, Bitcoin isn't domestic to the US or any other country. It's a worldwide community, as can be seen in this [https://bitcointalk.org/?topic=2346.0 map of Bitcoin nodes].

== Bitcoin will only enable tax evaders which will lead to the eventual downfall of civilization ==

Cash transactions hold the same level of anonymity but are still taxed successfully. It is up to you to follow the applicable state laws in your home country, or face the consequences.

While it may be easy to transfer bitcoins anonymously, ''spending'' them anonymously on tangibles is just as hard as spending any other kind of money anonymously. Tax evaders are often caught because their lifestyle and assets are inconsistent with their reported income, and not necessarily because government is able to follow their money.

== Bitcoins can be printed/minted by anyone and are therefore worthless ==

Bitcoins are not printed/minted. Instead, [[Blocks]] are computed by miners and for their efforts they are awarded a specific amount of bitcoins and transaction fees paid by others. See [[Mining]] for more information on how this process works.

== Bitcoins are worthless because they're based on unproven cryptography ==

SHA256 and [[ECDSA]] which are used in Bitcoin are well-known industry standard algorithms. SHA256 is endorsed and used by the US Government and is standardized (FIPS180-3 Secure Hash Standard). If you believe that these algorithms are untrustworthy then you should not trust Bitcoin, credit card transactions or any type of electronic bank transfer. Bitcoin has a sound basis in well understood cryptography.

== Early adopters are unfairly rewarded ==

Early adopters are rewarded for taking the higher risk with their time and money. The capital invested in bitcoin at each stage of its life invigorated the community and helped the currency to reach subsequent milestones. Arguing that early adopters do not deserve to profit from this is akin to saying that early investors in a company, or people who buy stock at a company IPO (Initial Public Offering), are unfairly rewarded.

This argument also depends on bitcoin early adopters using bitcoins to store rather than transfer value. The daily trade on the exchanges (as of Jan 2012) indicates that smaller transactions are becoming the norm, indicating trade rather than investment. In more pragmatic terms, "fairness" is an arbitrary concept that is improbable to be agreed upon by a large population. Establishing "fairness" is no goal of Bitcoin, as this would be impossible.

Looking forwards, considering the amount of publicity bitcoin received as of April 2013, there can be no reasonable grounds for complaint for people who did not invest at that time, and then see the value (possibly) rising drastically higher.

By starting to mine or acquire bitcoins today, you too can become an early adopter.

== 21 million coins isn't enough; doesn't scale ==

One Bitcoin is divisible down to eight decimal places. There are really 2,099,999,997,690,000 (just over 2 quadrillion) maximum possible atomic units in the bitcoin system.

The value of "1 BTC" represents 100,000,000 of these. In other words, each bitcoin is divisible by up to 108.

As the value of the unit of 1 BTC grew too large to be useful for day to day transactions, people started dealing in smaller [[Units|units]], such as milli-bitcoins (mBTC) or micro-bitcoins (μBTC).

== Bitcoins are stored in wallet files, just copy the wallet file to get more coins! ==

No, your wallet contains your secret keys, giving you the rights to spend your bitcoins. Think of it like having bank details stored in a file. If you give your bank details (or bitcoin wallet) to someone else, that doesn't double the amount of money in your account. You can spend your money or they can spend your money, but not both.

== Lost coins can't be replaced and this is bad ==

Bitcoins are divisible to 0.00000001, so there being fewer bitcoins remaining is not a problem for the currency itself. If you lose your coins, all other coins will go up in value a little. Consider it a donation to all other bitcoin users.

A related question is: Why don't we have a mechanism to replace lost coins? The answer is that it is impossible to distinguish between a 'lost' coin and one that is simply sitting unused in someone's wallet.

== It's a giant ponzi scheme ==
In a [[Wikipedia:Ponzi_scheme|Ponzi Scheme]], the founders persuade investors that they’ll profit. Bitcoin does not make such a guarantee. There is no central entity, just individuals building an economy.

A Ponzi scheme is a zero sum game. In a ponzi scheme, early adopters can only profit at the expense of late adopters, and the late adopters always lose. Bitcoin can have a win-win outcome. Earlier adopters profit from the rise in value as Bitcoin becomes better understood and in turn demanded by the public at large. All adopters benefit from the usefulness of a reliable and widely-accepted decentralized peer-to-peer currency.<ref name=Jeff_Tucker>cf. {{cite news | author-link = Wikipedia:Jeffrey_Tucker | url = http://libertarianstandard.com/2013/12/01/ponzi-logic-debunking-gary-north/ | title = Ponzi Logic: Debunking Gary North | last = Tucker | first = Jeffrey | date = 1 December 2013 | work = The Libertarian Standard | accessdate = 2015-04-11}}</ref>

It is also important to note that [[Satoshi Nakamoto]], creator of bitcoin, has never spent a bitcoin (other than giving them away when they were worthless) which we can verify by checking the blockchain.

== Finite coins plus lost coins means deflationary spiral ==
As deflationary forces may apply, economic factors such as hoarding are offset by human factors that may lessen the chances that a [[Deflationary spiral]] will occur.

== Bitcoin can't work because there is no way to control inflation ==

Inflation is simply a rise of prices over time, which is generally the result of the devaluing of a currency. This is a function of supply and demand. Given the fact that the supply of bitcoins is fixed at a certain amount, unlike fiat money, the only way for inflation to get out of control is for demand to disappear. Temporary inflation is possible with a rapid adoption of Fractional Reserve Banking but will stabilize once a substantial number of the 21 million "hard" bitcoins are stored as reserves by banks.

Given the fact that Bitcoin is a distributed system of currency, if demand were to decrease to almost nothing, the currency would be doomed anyway.

The key point here is that Bitcoin as a currency can't be inflated by any single person or entity, like a government, as there's no way to increase supply past a certain amount.

Indeed, the most likely scenario, as Bitcoin becomes more popular and demand increases, is for the currency to increase in value, or deflate, until demand stabilizes.

== The Bitcoin community consists of anarchist/conspiracy theorist/gold standard 'weenies' ==

The members of the community vary in their ideological stances. While it may have been started by ideological enthusiasts, Bitcoin now speaks to a large number of regular pragmatic folk, who simply see its potential for reducing the costs and friction of global e-commerce.

== Anyone with enough computing power can take over the network ==

CONFIRMED, see [[Weaknesses]].

That said, as the network grows, it becomes harder and harder for a single entity to do so. Already the Bitcoin network's computing power is quite ahead of the world's fastest supercomputers, together.

What an attacker can do once the network is taken over is quite limited. Under no circumstances could an attacker create counterfeit coins, fake transactions, or take anybody else's money. An attacker's capabilities are limited to taking back their own money that they very recently spent, and preventing other people's transactions from receiving confirmations. Such an attack would be very costly in resources, and for such meager benefits there is little rational economic incentive to do such a thing.

Furthermore, this attack scenario would only be feasible for as long as it was actively underway. As soon as the attack stopped, the network would resume normal operation.

== Bitcoin violates governmental regulations ==

There is no known governmental regulation which disallows the use of Bitcoin.

See also: the "[[#Bitcoins_are_illegal_because_they.27re_not_legal_tender|Bitcoins are illegal because they're not legal tender]]" myth.

== Fractional reserve banking is not possible ==

It is possible. See the main article, [[Fractional Reserve Banking and Bitcoin]]

== After 21 million coins are mined, no one will generate new blocks ==

When operating costs can't be covered by the block creation bounty, which will happen some time before the total amount of BTC is reached, miners will earn some profit from [[transaction fees]]. However unlike the block reward, there is [http://bitcoin.stackexchange.com/questions/876/how-much-will-transaction-fees-eventually-be/895#895 no coupling between transaction fees and the need for security], so there is less of a guarantee that the amount of [[Mining|mining]] being performed will be sufficient to maintain the network's security.

== Bitcoin has no built-in chargeback mechanism, and this isn't good ==

'''Why some people think this is bad''': Chargebacks are useful for limiting fraud. The person handling your money has a responsibility to prevent fraud. If you buy something on eBay and the seller never ships it, PayPal takes funds from the seller's account and gives you back the money. This strengthens the eBay economy, because people recognize that their risk is limited and are more willing to purchase items from risky sellers.

'''Why it's actually a good thing''': Bitcoin is designed such that your money is yours and yours alone. Allowing chargebacks implies that it is possible for another entity to take your money from you. You can have either total ownership rights of your money, or fraud protection, but not both. That said, nothing inherent in the dollar or euro or any other currency is necessary for chargebacks to be possible, and likewise, nothing prevents the creation of PayPal-like services denominated in Bitcoin that provide chargebacks or fraud protection.

The statement "The person handling your money has a responsibility to prevent fraud" is still true; the power has been shifted into your own hands. Fraud will always exist. It's up to you to only send bitcoins to trusted entities. It is possible to trust an online identity without ever knowing their physical identity; see the [http://wiki.bitcoin-otc.com/wiki/OTC_Rating_System OTC Web of Trust].

== Quantum computers would break Bitcoin's security ==

While ECDSA is indeed not secure under quantum computing, quantum computers don't yet exist and probably won't for a while.
The DWAVE system often written about in the press is, even if all their claims are true, not a quantum computer of a kind that could be used for cryptography.
Bitcoin's security, when used properly with a new address on each transaction, depends on more than just ECDSA: Cryptographic hashes are much stronger than ECDSA under QC.
Bitcoin's security was designed to be upgraded in a forward compatible way and could be [http://en.wikipedia.org/wiki/Post-quantum_cryptography upgraded] if this were considered an imminent threat.

See the implications of quantum computers on public key cryptography here http://en.wikipedia.org/wiki/Quantum_computer#Potential

The ''risk'' of quantum computers is also there for financial institutions, like banks, because they heavily rely on cryptography when doing transactions.

== Bitcoin makes self-sufficient artificial intelligence possible ==
[[StorJ]]<ref>[http://garzikrants.blogspot.com/2013/01/storj-and-bitcoin-autonomous-agents.html StorJ And Bitcoin Autonomous Agents]</ref>, a theorized autonomous agent which utilizes humans to build itself and issues autonomous payments for improvement work done, is not a conscious entity. Whatever AI is possible, is not going to be magically more possible simply because it could incentivize human behaviour with pseudonymous Bitcoin payments.

== [[Mining|Bitcoin mining]] is a waste of energy and harmful for ecology ==
No more so than the wastefulness of mining gold out of the ground, melting it down and shaping it into bars, and then putting it back underground again. Not to mention the building of big fancy buildings, the waste of energy printing and minting all the various fiat currencies, the transportation thereof in armored cars by no less than two security guards for each who could probably be doing something more productive, etc.

As far as mediums of exchange go, Bitcoin is actually quite economical of resources, compared to others.

'''Economic Argument 1'''

[[Mining|Bitcoin mining]] is a highly competitive, dynamic, almost [http://en.wikipedia.org/wiki/Perfect_market perfect], market. Mining rigs can be set up and dismantled almost anywhere in the world with relative ease. Thus, market forces are constantly pushing mining activity to ''places'' and ''times'' where the marginal price of electricity is low or zero. These electricity products are cheap for a reason. Often it’s because the electricity is difficult (and wasteful) to transport, difficult to store, or because there is low demand and high supply. Using electricity in this way is a lot less wasteful than simply plugging a mining rig into the mains indiscriminately.

For example, Iceland produces an excess of cheap electricity from renewable sources, but it has no way of exporting electricity because of its remote location. It is conceivable that at some point in future Bitcoin mining will only be profitable in places like Iceland, and unprofitable in places like central Europe, where electricity comes mostly from nuclear and fossil sources.

Market forces could even push mining into innovative solutions that have an effective electricity consumption of ''zero''. Mining always produces heat equivalent to the energy consumed - for example, 1000 watts of mining equipment produces the same amount of heat as a 1000 watt heating element used in an electric space heater, hot tub, water heater, or similar appliance. Someone already in a willing position to incur the cost of electricity for its heat value alone could run mining equipment specially designed to mine bitcoins while capturing and utilizing the heat produced, without incurring any energy costs beyond what they already intended to spend on heating.

(Note that this is just an example; mining will not always produce heat equivalent to the energy consumed because some energy is inevitably released as electromagnetic radiation, among others.)

'''Economic Argument 2'''

When the environmental costs of mining are considered, they need to be weighed up against the benefits. If you question Bitcoin on the grounds that it consumes electricity, then you should also ask questions like this: Will Bitcoin promote economic growth by freeing up trade? Will this speed up the rate of technological innovation? Will this lead to faster development of green technologies? Will Bitcoin enable new, border crossing [http://en.wikipedia.org/wiki/Smart_grid smart grid] technologies? …

Dismissal of Bitcoin because of its costs, while ignoring its benefits, is a dishonest argument. In fact, any environmental argument of this type is dishonest, not just pertaining to Bitcoin. Along similar lines, it could be argued that wind turbines are bad for the environment because making the steel structure consumes energy.

'''Ratio of Capital Costs versus Electrical Costs'''

The BFL Jalapeno hashes at 5.5 Gh/s using 30W. That device consumes about $40 per year in electricity (using U.S. residential average of about $0.15 per kWh.) But the device costs over $300 including shipping. Thus just about a quarter of all costs over a two-year useful life goes to electricity. This compares to GPUs where more than 90% of costs over a two-year life went to electricity. Even more efficient designs can be expected in the future.

== Shopkeepers can't seriously set prices in bitcoins because of the volatile exchange rate ==

The assumption is that bitcoins must be sold immediately to cover operating expenses. If the shopkeeper's back-end expenses were transacted in bitcoins as well, then the exchange rate would be irrelevant. Larger adoption of Bitcoin would make prices [http://en.wikipedia.org/wiki/Sticky_%28economics%29 sticky]. Future volatility is expected to decrease, as the size and depth of the market grows.

In the meantime, many merchants simply regularly pull the latest market rates from the exchanges and automatically update the prices on their websites. Also you might be able to buy a put option in order to sell at a fixed rate for a given amount of time. This would protect you from drops in price and simplify your operations for that time period.

== Like Flooz and e-gold, bitcoins serve as opportunities for criminals and will be shut down ==

* Visa, MasterCard, PayPal, and cash all serve as opportunities for criminals as well, but society keeps them around due to their recognized net benefit.
* Hopefully Bitcoin will grow to the point where no single organization can disrupt the network, or would be better served by helping it.
* Terrorists fly aircraft into buildings, but the governments have not yet abolished consumer air travel. Obviously the public good outweighs the possible bad in their opinion.
* Criminal law differs between jurisdictions.

== Bitcoins will be shut down by the government just like Liberty Dollars were ==

Liberty Dollars started as a commercial venture to establish an alternative US currency, including physical banknotes and coins, backed by precious metals. This, in and of itself, is not illegal. They were prosecuted under counterfeiting laws because the silver coins allegedly resembled US currency.

Bitcoins do not resemble the currency of the US or of any other nation in any way, shape, or form. The word "dollar" is not attached to them in any way. The "$" symbol is not used in any way.

Bitcoins have no representational similarity whatsoever to US dollars.

Of course, actually 'shutting down' Liberty Dollars was as easy as arresting the head of the company and seizing the offices and the precious metals used as backing. The decentralized Bitcoin, with no leader, no servers, no office, and no tangible asset backing, does not have the same vulnerability.

== Bitcoin is not decentralized because the developers can dictate the software's behavior ==

The Bitcoin protocol was originally defined by Bitcoin's inventor, [[Satoshi Nakamoto]], and this protocol has now been widely accepted as the standard by the community of miners and users.

Though the developers of the original Bitcoin client still exert influence over the Bitcoin community, their power to arbitrarily modify the protocol is very limited. Since the release of Bitcoin v0.3, changes to the protocol have been minor and always in agreement with community consensus.

Protocol modifications, such as increasing the block award from 25 to 50 BTC, are not compatible with clients already running in the network. If the developers were to release a new client that the majority of miners perceives as corrupt, or in violation of the project’s aims, that client would simply not catch on, and the few users who do try to use it would find that their transactions get rejected by the network.

There are also other [[:Category:Clients|Bitcoin clients made by other developers]] that adhere to the Bitcoin protocol. As more developers create alternative clients, less power will lie with the developers of the original Bitcoin client.

== Bitcoin is a pyramid scheme ==

Bitcoin is nearly opposite of a [[Wikipedia:Pyramid_scheme|pyramid scheme]] in a mathematical sense. Because Bitcoins are algorithmically made scarce, no exponential benefit is derived from introducing new users to use of it. There is a quantitative benefit in having additional interest or demand, but this is in no way exponential.<ref name="Jeff_Tucker" />

== Bitcoin was hacked ==

In the history of Bitcoin, there has never been an attack on the [[block chain]] that resulted in stolen money from a confirmed output. Neither has there ever been a reported theft resulting directly from a vulnerability in the [[Original Bitcoin client|original Bitcoin client]], or a vulnerability in the protocol. Bitcoin is secured by standard cryptographic functions. These functions have been peer reviewed by cryptography experts and are considered unlikely to be breakable in the foreseeable future.

It is safe to say that the currency itself has never been 'hacked'. However, several major ''websites'' using the currency have been hacked, often resulting in high profile Bitcoin heists. These heists are misreported in some media as hacks on Bitcoin itself. An analogy: Just because someone stole US dollars from a supermarket till, doesn’t mean that the US dollar as a currency has been 'hacked'.

Most bitcoin thefts are the result of inadequate [[Securing your wallet|wallet security]]. In response to the wave of thefts in 2011 and 2012, the community has developed risk-mitigating measures such as [[Wallet_encryption|wallet encryption]], support for [[BIP_0011|multiple signatures]], [[How_to_set_up_a_secure_offline_savings_wallet|offline wallets]], [[Paper_wallet|paper wallets]], and [[Hardware_wallet|hardware wallets]]. As these measures gain adoption by merchants and users, the number of thefts drop.

==References==
<references/>

[[en:Myths]]
[[de:Mythen]]
[[ru:Мифы о биткоине]]