Difference between revisions of "Seed phrase"
(Created page with "A '''seed phrase''', '''seed recovery phrase''' or '''backup seed phrase''' is a list of words which store all the information needed to recover a Bitcoin...") |
|||
| Line 1: | Line 1: | ||
| − | + | =DISCLAIMER= | |
| + | This article is a direct copy of the original https://en.bitcoin.it/wiki/Seed_phrase and has not been checked for correctness or edited. | ||
| + | 2 December 2019 | ||
| + | Expected review by: 15 December 2019 | ||
| − | + | Review BJL 20191202 | |
| − | Seed phrases are | + | |
| + | |||
| + | A '''seed phrase''', '''seed recovery phrase''' or '''backup seed phrase''' is a list of words which correspond to the master private key of a Bitcoin wallet. In typical usage, a wallet will generate a seed phrase and instruct the user to write it down on paper. If the user's computer breaks or their hard drive becomes corrupted, they can download the same wallet software again and use the paper backup to deterministically re-generate their wallet. | ||
| + | |||
| + | Anybody with access to the phrase can steal the bitcoins, so it must be kept safe. | ||
| + | |||
| + | Seed phrases are the most frequently encountered means of backing up Bitcoin wallets. | ||
== Example == | == Example == | ||
| Line 12: | Line 21: | ||
The word order is important. | The word order is important. | ||
| − | |||
| − | |||
== Explanation == | == Explanation == | ||
| − | A simplified explanation of how seed phrases work is that the wallet software has a list of words taken from a dictionary, with each word assigned to a number. The seed phrase | + | A simplified explanation of how seed phrases work is that the wallet software has a list of words taken from a dictionary, with each word assigned to a number. The words in the seed phrase are each converted to their corresponding number and concatenated to generate the seed integer to a [[Deterministic wallet|deterministic wallet]]. From this seed integer the wallet generates all [[Private key|key pairs]] used in the wallet. |
| − | |||
| − | |||
| − | + | The English-language wordlist for the BIP39 standard has 2048 words, so if the phrase contained only 12 random words, the number of possible combinations would be 2048^12 = 2^132 and the phrase would have 132 bits of security. However, some of the data in a BIP39 phrase is not random,<ref>[https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki#Generating_the_mnemonic BIP39: Generating the mnemonic]</ref> so the actual security of a 12-word BIP39 seed phrase is only 128 bits. | |
== Two-Factor Seed Phrases == | == Two-Factor Seed Phrases == | ||
| − | + | Several wallets enable their users to generate seed phrases with an added layer of encryption to prevent someone who discovers the words from accessing the wallet. The password can be used to create a two-factor seed phrase where both ''"something you have"'' plus ''"something you know"'' is required to recover the wallet. | |
| − | |||
| − | The password can be used to create a two-factor seed phrase where both ''"something you have"'' plus ''"something you know"'' is required to | ||
This works by the wallet creating a seed phrase and asking the user for a password. Then both the seed phrase and extra word are required to recover the wallet. Electrum and some other wallets call the passphrase a '''"seed extension"''', '''"extension word"''' or '''"13th/25th word"'''. The BIP39 standard defines a way of passphrase-protecting a seed phrase. A similar scheme is also used in the Electrum standard. If a passphrase is not present, an empty string "" is used instead. | This works by the wallet creating a seed phrase and asking the user for a password. Then both the seed phrase and extra word are required to recover the wallet. Electrum and some other wallets call the passphrase a '''"seed extension"''', '''"extension word"''' or '''"13th/25th word"'''. The BIP39 standard defines a way of passphrase-protecting a seed phrase. A similar scheme is also used in the Electrum standard. If a passphrase is not present, an empty string "" is used instead. | ||
| − | |||
| − | |||
| − | |||
| − | |||
== Storing Seed Phrases for the Long Term == | == Storing Seed Phrases for the Long Term == | ||
| − | Most people write down phrases on paper but they can be stored in many other ways such as [[Brainwallet|memorizing]], engraving on metal, writing in the margins of a book | + | Most people write down phrases on paper but they can be stored in many other ways such as [[Brainwallet|memorizing]], engraving on metal, writing in the margins of a book or any other creative and inventive way. |
For storing on paper writing with pencil is much better than pen<ref>[http://www.joethorn.net/blog/2011/12/07/pencil-does-not-fade Pencil Does Not Fade]</ref><ref>[https://www.quora.com/How-do-I-maintain-a-paper-notebook-that-can-remain-for-years How do I maintain a paper notebook that can remain for years?]</ref>. Paper should be acid-free or archival paper, and stored in the dark avoiding extremes of heat and moisture<ref>[https://www.loc.gov/preservation/care/deterioratebrochure.html Essential facts about preservation of Paper]</ref><ref>[https://www.quora.com/If-I-write-with-a-pencil-on-my-notebook-will-the-writing-last-for-a-long-time-say-50-years-or-will-it-just-fade-away-gradually Writing in a notebook with pencil]</ref><ref>[http://copar.org/bulletin14.htm CoPAR: Creating records that will last]</ref>. | For storing on paper writing with pencil is much better than pen<ref>[http://www.joethorn.net/blog/2011/12/07/pencil-does-not-fade Pencil Does Not Fade]</ref><ref>[https://www.quora.com/How-do-I-maintain-a-paper-notebook-that-can-remain-for-years How do I maintain a paper notebook that can remain for years?]</ref>. Paper should be acid-free or archival paper, and stored in the dark avoiding extremes of heat and moisture<ref>[https://www.loc.gov/preservation/care/deterioratebrochure.html Essential facts about preservation of Paper]</ref><ref>[https://www.quora.com/If-I-write-with-a-pencil-on-my-notebook-will-the-writing-last-for-a-long-time-say-50-years-or-will-it-just-fade-away-gradually Writing in a notebook with pencil]</ref><ref>[http://copar.org/bulletin14.htm CoPAR: Creating records that will last]</ref>. | ||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
== Word Lists == | == Word Lists == | ||
| Line 72: | Line 63: | ||
* [[Deterministic wallet]] | * [[Deterministic wallet]] | ||
* [[Storing bitcoins]] | * [[Storing bitcoins]] | ||
| − | * [[Brainwallet]] | + | * [[Brainwallet]] |
* [https://github.com/6102bitcoin/FAQ/blob/master/seed.md FAQ regarding bitcoin seeds] - Look if this is good | * [https://github.com/6102bitcoin/FAQ/blob/master/seed.md FAQ regarding bitcoin seeds] - Look if this is good | ||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
Revision as of 02:56, 2 December 2019
DISCLAIMER
This article is a direct copy of the original https://en.bitcoin.it/wiki/Seed_phrase and has not been checked for correctness or edited. 2 December 2019 Expected review by: 15 December 2019
Review BJL 20191202
A seed phrase, seed recovery phrase or backup seed phrase is a list of words which correspond to the master private key of a Bitcoin wallet. In typical usage, a wallet will generate a seed phrase and instruct the user to write it down on paper. If the user's computer breaks or their hard drive becomes corrupted, they can download the same wallet software again and use the paper backup to deterministically re-generate their wallet.
Anybody with access to the phrase can steal the bitcoins, so it must be kept safe.
Seed phrases are the most frequently encountered means of backing up Bitcoin wallets.
Example
An example of a seed phrase is:
witch collapse practice feed shame open despair creek road again ice least
The word order is important.
Explanation
A simplified explanation of how seed phrases work is that the wallet software has a list of words taken from a dictionary, with each word assigned to a number. The words in the seed phrase are each converted to their corresponding number and concatenated to generate the seed integer to a deterministic wallet. From this seed integer the wallet generates all key pairs used in the wallet.
The English-language wordlist for the BIP39 standard has 2048 words, so if the phrase contained only 12 random words, the number of possible combinations would be 2048^12 = 2^132 and the phrase would have 132 bits of security. However, some of the data in a BIP39 phrase is not random,<ref>BIP39: Generating the mnemonic</ref> so the actual security of a 12-word BIP39 seed phrase is only 128 bits.
Two-Factor Seed Phrases
Several wallets enable their users to generate seed phrases with an added layer of encryption to prevent someone who discovers the words from accessing the wallet. The password can be used to create a two-factor seed phrase where both "something you have" plus "something you know" is required to recover the wallet.
This works by the wallet creating a seed phrase and asking the user for a password. Then both the seed phrase and extra word are required to recover the wallet. Electrum and some other wallets call the passphrase a "seed extension", "extension word" or "13th/25th word". The BIP39 standard defines a way of passphrase-protecting a seed phrase. A similar scheme is also used in the Electrum standard. If a passphrase is not present, an empty string "" is used instead.
Storing Seed Phrases for the Long Term
Most people write down phrases on paper but they can be stored in many other ways such as memorizing, engraving on metal, writing in the margins of a book or any other creative and inventive way.
For storing on paper writing with pencil is much better than pen<ref>Pencil Does Not Fade</ref><ref>How do I maintain a paper notebook that can remain for years?</ref>. Paper should be acid-free or archival paper, and stored in the dark avoiding extremes of heat and moisture<ref>Essential facts about preservation of Paper</ref><ref>Writing in a notebook with pencil</ref><ref>CoPAR: Creating records that will last</ref>.
Word Lists
Generally a seed phrase only works with the same wallet software that created it. If storing for a long period of time it's a good idea to write the name of the wallet too.
The BIP39 English word list has each word being uniquely identified by the first four letters, which can be useful when space to write them is scarce.
Alternative name "Mnemonic Phrase"
Seed phrases are sometimes called "mnemonic phrases" especially in older literature. This is a bad name because the word mnemonic implies that the phrase should be memorized. It is less misleading to call them seed phrases.
The power of backups
An especially interesting aspect in the power of paper backups is allowing your money to be two places at once. At the London Inside Bitcoin conference the keynote speaker showed 25 paper backups they were carrying -- all password-protected. With that one can carry $100,000 which can instantly be moved to a phone or transferred yet with total security. If it's stolen then there is no risk because it is backed up elsewhere. That is powerful.<ref>https://www.reddit.com/r/Bitcoin/comments/2hmnru/poll_do_you_use_paper_wallets_why_why_not_what/</ref>
See Also
- BIP39 mnemonic phrase standard - Still applies? Deprecation schedule?
- Deterministic wallet
- Storing bitcoins
- Brainwallet
- FAQ regarding bitcoin seeds - Look if this is good