9

If you are missing the first word and you know the rest of the 11 words, there are 2048 possible mnemonics but only ~128 of them are valid. Using Python and this library you can print all the valid ones with this simple script: from btctools.HD import check, WORDS phrase = "{x} decrease enjoy credit fold prepare school midnight flower wrong false already" ...


5

It's not to do with length, but entropy. Humans are terrible at creating randomness, even what you think is hard to guess could in all probability be guessed with enough iteration. Family names for example are easy to guess, there's a finite number of them and a vast portion of names are from a set of only a few hundred. What's the chance of you ...


5

It would not be wise to do this. "Brainwallet" software is completely non-standardized, there's no guarantee that any two implementations handle the encoding of characters in the same way. Addition of UTF8/UTF16 these characters is also likely to be incredibly confusing, did you mean Tooxy or Тооху? Those strings look the same but one is a completely ...


5

Appending numbers doesn't open you up to any particular vulnerability, but using any human derived private key is an extremely poor idea. Markov chains are extraordinarily good at attacking passphrases, which is counter intuitive when most people assume an exhaustive search character by character.


4

Someone else already mentioned entropy. Humans are really bad at creating randomness. But that's only one part of it. The other part is time, and how it's on the attacker's side. An attacker can generate a lot of brainwallets with a lot of different words and phrases. Then they watch the blockchain to see if any of those addresses receive coins. If ...


4

A very, very long time. Oxford English Dictionary contains full entries for 171,476 words in current use. If you use only lower case letters and they are mostly random words (no phrases - "four score and seven years ago" is like having your password be "secret"), there are about 7.47e41 possibilities. At 50 million attempts per second, it'll be about 4....


4

Once you have the address you'd like the coins to be in, just make one transaction for the total amount of your balance going to that address. The inputs from all transactions leading into the sending wallet will be combined into a single output automatically. Or are you asking how to create the brain wallet in the first place?


4

This question is marked as answered, but it was answered back in 2013. The answer has changed since then. Here's a reply from 2015. Brainwallets are hideously insecure. Don't use them. EVER! Don't take my word for it. Here are some references: http://www.coindesk.com/new-cracking-tool-exposes-major-flaw-in-bitcoin-brainwallets/ https://en.bitcoin.it/...


4

They can be made a heck-of-a-lot safer with simple key-stretching. The WarpWallet runs Scrypt on your passphrase, and outputs a string in the full 256-bit keyspace. It's at least 1000x more expensive to guess a WarpWallet address than a standard brainwallet address. And if you had access to high-end scrypt-computing hardware, you're probably better off ...


4

BIP38 wallets are significantly more secure and are resistant to brute-force attacks when a decent passphrase is used. Generally the term "Brain Wallet" refers to one in which the private key is derived from a phrase you make up. These have been shown to be insecure because humans are bad at entropy and generally anything easy enough to remember is not ...


4

A bitcoin generator can generate an address. i.e. https://brainwalletx.github.io/


4

Firstly, it is highly recommended not to use a brainwallet, your coins will be stolen. But in general, if you have a private key, there is no way to obtain the 12 word recovery phrase from it. That is because the 12 word phrase is used as a seed to generate a hierarchical deterministic master extended private key, as described in BIP 39 and BIP 32 and this ...


3

The compressed keys are better for use. Because the redeem transaction size will be smaller, so one can save a fee. Unfortunately, the original design of brainwallets created uncompressed keys. And now this setting is default. It is too late to change the default behavior of this. Let us say that "uncompressed" keys are standard de-facto.


3

Answer was here: https://en.bitcoin.it/wiki/Wallet_import_format To make brainwallet need to take a sha256 of password: # echo -n 'yourbrainwalletpassword' | sha256sum 8abe468e0d5a814c644d9517ae35b36666d554b7bd682fa28c39e90d0cb5f91a I've write a little bash script: declare -a base58=( 1 2 3 4 5 6 7 8 9 A B C D E F G H J K L M N P Q R S T ...


3

What follows is an educated guess, not certain statements, and is based on Electrum's brainwallet phrases (just figured it'd be a good example), not other schemes or human-generated ones. No, a miner can't easily be tricked into doing it (e.g. solely by a rogue pool), but can be programmed to try to crack brainwallet phrases. This is because ordinary ...


3

A series of random words (not a sentence!) long enough to use as a secure key should be about 12 words long, which could be around 100 characters long (figuring they're fairly long, 7-8 average, with a space in between). This gives you 2^128 combinations that you might have to try to crack your password, which might take about 1 billion billion years. A ...


3

There are no warnings given on the site about the safety of this. How secure are brain wallets? As secure as you make them, in my opinion. Let's say you use all 92 characters in your password, and it's 30 letters long. That gives you an entropy of 92^30, or 195 bits. It would take more energy than can possibly be produced on earth to brute force it. https:/...


3

If anything, then the contest just proved that brainwallets is more secure than one would think. After a few hours the "lorem ipsum dolor sit amet" address was "cracked", after two weeks the rest wasn't cracked. The author of the contest (linjaaho) gave A LOT of hints, but even though that, it took around two days for the rest of the addresses to be cracked ...


3

Any 256-bit value can be a valid secp256k1 ECDSA private key. Strictly speaking, there's an upper limit that's slightly lower than 2^256, but you can just wrap them around. So yes, you can just use SHA256(passphrase) to generate a private key.


3

200 characters sounds a bit excessive to me. What are the chances of a typo while trying to enter your password, just to generate the private key? My suggestion, if you wish to use a secure enough password, is first to make sure you are not largely using actual words or phrases. Certainly, use information only you know, organized in a way only you could ...


3

A short working example is worth a 1000 words. % echo -n "This is a VERY pooor low entropy brain wallet" | bx base16-encode | bx sha256 | cut -c 1-32 | bx mnemonic-new health boil host ostrich fire spike body solar collect harvest catalog crystal Use something like like ent to measure the entropy of you brainwallet text to ensure the text entropy is ...


3

Generating from the hash of a string is known as a Brainwallet. This has the advantage that it is potentially easier to remember and recreate your wallet if you lose the keys. This also have the disadvantage that people are terrible at picking entropy, and it is trivial to crack most brainwallets via brute force. You have far more security relying on ...


2

There are roughly 170,000 words in the english dictionary according to this link. If you combine 4 random words (170,000^4) , you get 8.3*10^20 potential combinations which is more than 2^64 (1.8*10^19). However 64 bits of security is generally considered weak these days. Bitcoin uses 256 bit keys (1.1*10^77 combinations) so if you want that level of ...


2

We made a much improved version of brainwallet that uses scrypt key-stretching to protect your secret key. See it here: https://keybase.io/warp. There's currently an unbroken 20BTC challenge for an 8-letter passphrase.


2

Brainwallet.org doesn't make this terribly clear: choosing a compressed versus an uncompressed address is not choosing between two different versions of the same address, but rather two different addresses based on the same secret exponent. Sending bitcoin to one address will not be accessible by the other, as they are technically independent. With that in ...


2

In a way, this is how deterministic wallets work: All keys and addresses are derived from a secret pass phrase. The "wallet" in this case is the description of the algorithm, which is "stored" publicly.


2

If it is easy to remember, it is almost certainly easy to guess. And by guess, I don't mean a single person trying a few sentences in some time. I mean exposing yourself to a brute force attack by the entire world (the block chain data is public), for eternity.


2

Brain wallets use your secret phrase to deterministically generate keys for you, meaning that you can never lose your wallet and there is no need to print it (except for extra-safe keeping). Hence the name, "brain" wallet (not paper wallet). But they have the downside that human chosen, and memorable, passphrases are usually easier to break. So in this sense,...


2

No. Most brainwallets (assuming a more conventional brainwallet like one from brainwallet.org and not a seed-based one) are made by passing a passphrase through one round of SHA256. ASICs are designed to do two rounds.


2

BIP38 allows you to hide your private key in plain sight. Nobody knows what the private key is until they decrypt it with the password. A brainwallet is essentially generating a private key by hashing a password or passphrase. You can generate a private key using random or pseudorandom sources, or you can hash a password or passphrase. You can then, if ...


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