What are ALL the ways to store bitcoin wallets?

[ArticMine]

Never knew you could store BTC on floppy dicks.

Tattoos have been mentioned already.

But hard to read when it's floppy....

Hard but not impossible which is why floppy disks particularly the older 5.25in type can be an excellent way to back up bitcoins in certain situations. The idea in is to slow down an attacker long enough in order to empty the wallet of bitcoins. Consider the following situation. One has one's BTC in a brain wallet; however one also wants to ensure that ones estate can access one's BTC after one's death but only after one's death.  One possible solution may be to place the private keys on a paper wallet in a bank safety deposit box. Then when the owner of the bitcoins dies, the executor of the estate will have after probate access to the safety deposit box and the bitcoin keys. But what happens if the bank safety deposit box is compromised, an attacker will also have immediate access to the bitcoin keys.  Now instead save the bitcoin keys in clear text on a file in a 5.25in floppy disk and place the 5.25in floppy disk in the bank safety deposit box.  In this case the attacker has to first be able to read the 5.25in floppy disk, and this gives the owner of the bitcoins plenty of time to empty the wallet. On the other hand the executor of the estate is also slowed down; however in this case it does not really matter since it can take months to probate an estate in any event.

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[uyjulian]

Never knew you could store BTC on floppy dicks.

Tattoos have been mentioned already.

But hard to read when it's floppy....

Hard but not impossible which is why floppy disks particularly the older 5.25in type can be an excellent way to back up bitcoins in certain situations. The idea in is to slow down an attacker long enough in order to empty the wallet of bitcoins. Consider the following situation. One has one's BTC in a brain wallet; however one also wants to ensure that ones estate can access one's BTC after one's death but only after one's death.  One possible solution may be to place the private keys on a paper wallet in a bank safety deposit box. Then when the owner of the bitcoins dies, the executor of the estate will have after probate access to the safety deposit box and the bitcoin keys. But what happens if the bank safety deposit box is compromised, an attacker will also have immediate access to the bitcoin keys.  Now instead save the bitcoin keys in clear text on a file in a 5.25in floppy disk and place the 5.25in floppy disk in the bank safety deposit box.  In this case the attacker has to first be able to read the 5.25in floppy disk, and this gives the owner of the bitcoins plenty of time to empty the wallet. On the other hand the executor of the estate is also slowed down; however in this case it does not really matter since it can take months to probate an estate in any event.

You can you a 2 factor key.  Give one half to your family now.  the other half goes to your attorney/accountant, or whoever would handle your estate.  That way nobody has access until they join the 2 keys.

Here's how I do it:

I put one half of the key on a 5.25in floppy disk and another on a 3.5in disk. I give the 5.25in one to my family and the 3.5in one to my other family. I make sure the 3.5in one is formatted in HFS and the 5.25in in ProDOS.

[DrG]

How many places can you think to store a short string of numbers?

Convert to binary, make a binary painting for your wall.
Tattoo.
Write it in the wet cement of the foundation of your house before building it.
Piece of paper in a safe deposit box.
Hidden in a jpeg.
E-mail it to yourself through "future me".
Etch it into something you wear, ring, dog collars, necklace, etc.

Wow, somebody else thinks like me. I did that when I built my house 2 years ago.  Of course I left a few digits out of the full key, those are in another hidden area to don't tearing up my house 

[hashman]

Nice ideas but I am looking for something I can put in a tooth. 

[lettucebee]

Hey people, I really want to understand this, but you're ahead of me.  I need this to be explained like I'm a 5 year old.

I am familiar with the wallet.dat file.  It's an object, a FILE, that I protect.  But I do not understand where, when, or how I extract a "private key".  Nor do I understand how the private key relates to blockchain.info. 

Can someone explain this stuff or give me a link? 

I've been waxing on to my friends about bitcoin, but when we get to wallet security enthusiasm wanes.

Thanks.

[Dabs]

You can use bitcoin-qt to extract the private keys of the public keys that are displayed.

You can use pywallet (jackjack fork) to dump all the private keys of the wallet.dat file.

[niko]

Hey people, I really want to understand this, but you're ahead of me.  I need this to be explained like I'm a 5 year old.

I am familiar with the wallet.dat file.  It's an object, a FILE, that I protect.  But I do not understand where, when, or how I extract a "private key".  Nor do I understand how the private key relates to blockchain.info.  

Can someone explain this stuff or give me a link?  

I've been waxing on to my friends about bitcoin, but when we get to wallet security enthusiasm wanes.

Thanks.

Private key is a random number (may be expressed as a string of random characters, of course). It is private because, presumably, only the person who created it knows it. Note, "random" can be anything (with some technical limitations), including, for example, a hash of a sentence. This is convenient if you wish to store private keys in your brain.

Public key is calculated from the priv key using the ECDSA. Note, this is a one-way function: calculating the publoc key from the private key is easy, finding out the priv key when a public key is known is practically impossible.

Bitcoin address is calculated as a one-way function of the public key. Specifically, it is a double hash of pub key, ripemd160(sha256(pubkey)).

To spend (send) coins currently associated with a given address, your client (wallet program) signs a message about the spend from the corresponding public key, and message is signed with the corresponding private key. Note, the way digital signature works is that anyone who knows the public key can check that the signature was made using the valid private key, without knowing the private key. All nodes in the network can then verify that the message is valid, and broadcast it further. Eventually, a mining node will create a new block (every 10 minutes on average), and include this message ("spend") into this block, thus making it official. Note, you can only spend the complete amount of coins associated with an address. If what you are sending is less than that, the rest goes to a new address of yours. Your total balance is still correct, of course.

What your wallet software (bitcoin-qt client, multibit, or any online wallet service) does is it creates key pairs for you, manages them, and checks balances associated with the keys/addresses you own (typically only showing you the total).

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Most clients will let you export ("dump") private keys. Refer to the documentation about the particular client you're using. You can then preserve private key(s) using any method discussed here. Most people print them out ("paper wallets").

You can keep the physical embodiments of your private keys hidden and secure, or you can encrypt the keys beforehand, or both. Note, bitcoin-qt client offers encryption of private keys in your wallet.dat.