Use walletnotify combined with JSON-RPC to move your funds upon receipt.

You shouldn't be converting public keys to a mnemonic.

Looks like it's back online now, but in case it happens again it's pretty easy to build a clone that updates in real-time with websocket.

Here's a fiddle:
https://jsfiddle.net/y6vxmLp3/

What the hell is a defi? Ok Greg, I'll hoard my tBTC.

Have fun!
https://blockstream.info/testnet/tx/308fe1ee86fc649bdee963daf91e0d0e92b5a8cae40fe946d79bc3de1880a9dd

Search google for paper wallet, grab any result, or an Ad is even better. Print it and put in your sock drawer. Put all your money on it before getting comfortable with spending (don't worry about change address, WTF are those anyway). Back up on dropbox, or post it here. 


In all seriousness, unless you are really advanced and/or a developer you are setting yourself up for failure with paper wallets. 


I love paper wallets personally, and I like building my own tools for key generation, storage and spending but for obvious reasons I can't recommend this approach to most users.

Bitcoin core wallet has absolutely no ability to import a mnemonic.

Bitcoin core wallet only allows import of single keys (importprivkey), or multiple keys (importmulti).

Bitcoin core also has the ability to turn off the HD wallet with --usehd=0 and just use non-deterministic key pairs.

HD wallets have long been plagued with lack of a standard and lead to people thinking that all they need is their seed words. Unfortunately this causes a false sense of security and users that don't know what they are doing. You need to understand how HD wallets work and which derivation path you are using, not just seed words. From there you can figure out which address have funds, and then you can import those specific key pairs.

Recently I've been working on a multisig paper wallet using the bitcoinjs library.

With any bitcoin wallet, the most important part is the safety of user's funds. Part of the design process included what user input can be provided, and how much information to provide back to the user. The more steps or parts to the process opens up the user to more chances to make mistakes.

The current layout I have is:

 - User provides an input for m and n for the m-of-n (ie 2 of 3, 3 of 5, etc)
 - CSPRNG provided by bitcoinjs-lib creates n key pairs, and those public keys are used to create the multisig P2SH address.
 - Output to user is the P2SH address on the left-hand side, and on the right-hand side the first private key out of n keys.
 - The additional private keys can be cycled through using the arrow buttons above the private key QR code
 - Additional output to the user includes the public keys (and qr codes) and the sequence they were used to create the address and redeem script.
 - User can save redeem script hex to a USB drive, OR if they want to stay true to paper wallet regenerate the redeem script using the public key qr codes along with the `redeem-script.html` tool which can scan your public key qr codes with your webcam. Typing in by hand I suppose is a possible third option, but not likely or recommended considering the redeem script can be quite long.

To make the paper wallet more like a wallet, I have also added some additional standalone pages (tools) that will allow users to find UTXOs for specific addresses to build and sign transactions.

 - Users build transactions with UTXO selection using the `multisig-build.html` tool. (internet needed to fetch UTXOs)
 - Users sign transactions offline using the `multisig-sign.html` tool
 - Users are responsible for broadcasting the raw hex transactions

Drawbacks I am noticing:
 - building a transaction might be too advanced for some users
 - fees should be satoshis per byte like  segwitaddress.org instead of inputting exact fee in satoshis
 - users cant create an address from their own provided public keys (yet, will add in the future)
 - you tell me, what do you all think?

Here's the github repo: https://github.com/coinables/MultiSigAddress
and the domain I'm using: https://multisigaddress.org?testnet=true

It currently supports both testnet and mainnet. I recommend users stick with testnet unless they really know what they are doing.


Some nuances with creating a multisig wallet is there are multiple ways it could be implemented, whereas a standard single key address is just a private key and address. One of the challenges is the redeem script can be too long for a QR code. I was thinking maybe multiple QR codes, but that got ugly quick, so instead I went with displaying the public keys QR codes and printed out the redeem script, giving users multiple options.  This is the way I have decided to go, at least for a first attempt. Looking for thoughts, input, etc from others.

Same address moving big money again, this time its one of many inputs totaling a $1 billion dollar transaction moving all to a P2SH addr 

1JCe8z4jJVNXSjohjM4i9Hh813dLCNx2Sy

https://www.blockchain.com/btc/tx/4410c8d14ff9f87ceeed1d65cb58e7c7b2422b2d7529afc675208ce2ce09ed7d

It's important to make the distinction between storing actual files and the ability to write 80 arbitrary bytes to the OP_RETURN. To utilize the blockchain to store a pdf would require you to create many OP_RETURN outputs containing the raw bytes.  Then when ready to fetch the file you would have to combine all the output OP_RETURN data in order and then compile the raw bytes into an actual usable PDF. It's terribly inefficient and creates outputs that can never be spent, forever littering the UTXO set.

INTOTHEBLOCKCHAIN.info  is a bitcoin SaaS written in NodeJS that I am now putting up for auction.

No ads needed, users pay 0.0005 BTC to embed a message into the immutable Bitcoin Blockchain forever, and funds will go to site owner's wallet.
The site owner can accumulate roughly 1 BTC for every 2,000 messages embedded.

Site owner has to do nothing aside from renewing the domain name once a year and run a VPS for the site to run on (~$5/month).

Auction is taking place at flippa https://flippa.com/9334370-intotheblockchain-info

Do you mean without having to reindex? Unless you want to roll your own way of keeping track of transactions using a 3rd party websocket stream and a db or something, I think one solution is to run a pruned node and just generate addresses on the fly with the JSON RPC. You'll still have that one-time IBD, but the old blocks will be purged as it catches up. As long as these are new addresses you are generating with bitcoind it won't have to reindex since theoretically new addresses shouldn't have any prior transactions. Then you can use walletnotify to keep a running balance for each address on a db so you don't have to query bitcoind every time.

No, sha256 is a one-way hash function. To get the words from just a private key, sha256 would have to be broken and bitcoin would need to change it's base layer crypto algorithm.

Best to learn to do it yourself so you know you can re-create it in 10 years, you won't have to rely on bitaddress or whoever to still be around.
Probably one of the easiest things to do in python, even for non-programmers.

Download python 3.X
Install, make sure to check to include IDLE and adding python pip to PATH

Open command prompt and type

Now open up Python IDLE, file -> new

include the bitcoin package


Create a variable that includes your random words


Then run it through a sha256 hash


Now you can encode it into a WIF private key


Then to get the corresponding address, encode the public key then encode to base58

print out what you want

Then save the file, and run it (F5).

I'm surprised this one didn't make it in there 
https://www.amazon.com/Building-Bitcoin-Websites-Beginners-Development/dp/153494544X

Likely the amount you have specified in the send amount is greater than 46,160 satoshis (0.00012728 - 0.00008112 = 0.000046160), you have to account for the mining fee yourself when sending the request.

This was just something I threw together over the weekend using functions from someone else's repo as stated in the heading of the site. The address functions are using bitcoinjs which is a trusted library used by GreenAddress, Blockchain.info, Blocktrail and more. There's nothing funky going on, but it's good to be skeptical of pretty much everything especially wallets in the crypto space.

I'd like to echo this.

To be clear I am currently asking for concepts and portfolios to decide which designer I will proceed with. Please don't spend a ton of time on your concept, it can be on a napkin if need be; I just want to be sure we're both on the same page before committing. Thank you to everyone who has reached out so far. Don't worry I don't plan on dragging this out forever like some silly contest. Should have it decided within 24 hours.