30

There is no "official" when it comes to crypto. It definitely depends on your desire for security, how much you are going to be holding, what you plan on doing with the ETH or tokens stored there, and more. I recommend that people use whatever tool they can understand best and use with confidence. I do NOT believe that recommending someone who has ...


23

Cold storage has been discussed in the past on Ethereum's subreddit. Just to give my 2 cents, on Ubuntu I use the following on the command line: cat ~/.ethereum/keystore/<key_file> | qrencode -o qr_image.png Add option -l H to get a code that is easier to decode. The qrencode tool uses the open source libqrencode library, and can be installed using: ...


19

The safest way to store Ether and other altcoins (BTC, LTC, XRP, ETC) to date are hardware wallets such as Ledger Wallet. Owning one, I can say that the experience is painless and the security is beyond anything the web has to offer. While I don't know specifically how its security works, private keys are stored encrypted on a secure tamper-proof chip ...


18

Yes, both cryptocoins use the same elliptic curve SECP256K1. Perhaps a better alternative is to use a BIP32 wallet. You have a master key that is not directly used for transactions, but it is used to derive child keys than can be used. You can derive separate keys for bitcoin and ethereum. You will always be able to use the master key to sign transactions ...


16

MyEtherWallet.com There is a paper wallet generator available at myetherwallet.com. If you don't trust it, you can download it from github and run it offline. EthAddress.org There is another paper wallet generator available at ethaddress.org. Source code on github.


16

There's no official recommendation, but the go-ethereum team (behind geth) is committed to ensuring keys created by it will be supported in future versions. The keystore used by geth has strong passphrase encryption and has been through a couple security audits. Simply backing up the .ethereum/keystore folder is enough - would recommend multiple physical ...


15

The wallet promoted by ethereum.org is the official Mist based one which is linked on Ethereum site. Pros: Official, multiplatform, generic support for smart contracts, open source. Cons: Slow to sync (have to load the whole chain), sometime slow or freezing when contracts have a high update rate (The DAO during first weeks is a good example), not easy to ...


14

We at MyEtherWallet.com implemented an offline transaction tool to do exactly this. While most people who are cold-storage fanatics know command line and the inner-workings of gas price and nonce, this allows you to do it via GUI. Navigate to the "Offline Transaction" tab via your online computer. Here you will generate the current gas price and nonce. ...


12

Note: As the author of this post, I also authored a slight revision of this into the Official Homestead Documentation. I think if you are looking for a combination of ease-of-use and very good security, then a Mist multisignature wallet is your best bet. The Ethereum Foundation has (and still is) putting hundreds of thousands of dollars into Mist and it's ...


12

I've set something like this up myself. I've bought a silly simple laptop which runs a node which for obvious reasons it isn't connects to the network and has never been online. I use this device to sign transactions using the unofficial RPC method eth.signTransaction. You then take this method's output and stick it on a USB, move the contents to my other ...


10

Update: 2017-06-11 Available hardware wallets for Ethereum (in alphabetical order): Digital Bitbox KeepKey (now out of beta) Ledger Blue Ledger Nano S Trezor (in beta, see this answer for details)


9

Yes it is. Basic Formula: Install an Ethereum client to a computer that is freshly formatted (preferable), or at least one that is disconnected from the Internet. Generate your key(s) using an Ethereum client. Copy the Ethereum address generated and send 1 Ether to that address using another computer/device. Check an Ethereum blockchain explorer to make ...


9

Update 2017-06-05 YES -- Trezor is now compatible with Ethereum (ETH), Classic (ETC) and ERC-20 tokens via firmware 1.5.0. Can use the Trezor (Beta) Web Wallet or MyEtherWallet.com.


8

Alternatively if you are happy installing node.js and npm, you can choose from multiple Javascript projects handling keys: ethereumjs-wallet or keythereum if you want to code a bit or helpeth if you need a simple commandline tool. This command should give you the details needed: $ helpeth -p <your private key as a hex string> keyDetails Make sure ...


7

Ledger started shipping the Nano S Ether hardware wallet the last week of July 2016. Works for ETH, ETC and bitcoin at a cost of $65.


5

There is no dedicated and fully supported hardware wallet for Ethereum. There have been three announcements made so far: Troth by Digix A hardware wallet by Jaxx.io by end of 2016 Ledger Blue to be shipped later the year (an announcement about a demo Ethereum app BOLOS - the operating system it runs) It isn't trivial, but not that complicated to include ...


5

Trezor is a popular hardware wallet that supports Bitcoin and other alt coins Troth is on the way Troth is an Ethereum hardware vault for safely storing your Ether and Ethereum based tokens. We are looking at the end of March / Early April for the first working prototype. Troth is a Raspberry PI within, complete with a Touchscreen and 5mb camera ...


5

Yes, you can import a plaintext private key into geth with geth account import /path/to/key.prv Generating a private key is much trickier, though, since none of the main clients allow exporting unencrypted keys.


5

I agree with Mist multisig. One feature that is nice about this is you can create a contract wallet with 2 account owners and set a small daily limit. Then leave one account in your keystore on your computer and take the other account and store it off-line. That way if there is ever a compromise they cant empty your contract but can only take the daily ...


5

"Cold Wallet" typically means that the private key was generated on an offline computer. You send to the address generated, but the private key is never on a computer that is online. This is to mitigate the risk from viruses/keyloggers/etc. With Ethereum, you can also have a wallet that has a daily spend limit. (There is an example of this with the official ...


5

Will the wallets created at this moment in time be backwards compatible in the future? (Metropolis, Serenity, ...) I can confirm that MyEtherWallet will always provide backwards capabilities with older version of our encrypted versions, as well as common methods created by other wallets. We are currently in the process of switching to use the same ...


5

There are a few different reasons for verifying your key. To make sure you actually saved the private key and address correctly. e.g. You saved a private key but recorded the address 0x122... instead of 0x123... (note: you should avoid hand writing things anyways). To make sure you have all the necessary information, including the password. e.g. You ...


5

You can use MyEtherWallet offline signing on airgapped computer. https://www.myetherwallet.com/#offline-transaction


5

Each transaction requires a nonce (or sequence counter) value from your account. For each transaction you submit, the nonce is incremented. This is intentional to prevent replaying transactions. So no, you cannot send the same signed transaction again once it has been accepted by the network because the nonce value will not match.


4

Yes, you can simply generate pairs of unencrypted or encrypted private and public keys. For example, use this bulk key generator: 1,"0xb7d3a6d96960c2e9650822be7c1cc4ebe8bb3718","9a130892d949ab5faf678ac6295d3ab05a434448b824c0dc43bf86a4c2bbf747" 2,"0xbf3407c1231b3612dc6d2da07f32208ed1e17ebd","...


4

Printing the private key for ethereum in geth. This is done for creating a real *secure offline paperwallet in your own WM which afterwards stores the money independent from a program *. Based on this posts and another post that points out that the source code of geth can easily be changed to print out the private key. Here it how it goes. Create a ...


4

There is no security degradation, per se, but by spending from the account, you are announcing to the world that the keys are likely available on some network-connected computer. Since you are signing offline this is not true, but people may assume it is and attempt to target your funds. This could theoretically lead to attacks against the computer that you ...


4

If you want to work with browser-based solutions, you can also have a look at icebox. If you are happy to work with the command line, you have at least three options: geth - the go-ethereum client ethkey - the cpp-ethereum key management tool helpeth - the ethereumjs key management tool Both ethkey and helpeth will reveal the private key to you, but geth ...


4

You can write javascript code to open accounts and start transactions to your cold wallet. Basically you install a Ethereum node (for now geth is the best alternative here) on your server and interface your exchange program with web3 scripts that you can attach over ipc or json-rpc to the node.


3

You can try https://github.com/ConsenSys/icebox - it supports offline generation of key and manual adding of random numbers. The OS CSPRNG on Linux can be relied upon, as long as the computer has been doing a few things since first installing Linux (e.g. harddrive writes, mouse/keyboard inputs. Linux gathers entropy from such events into it's entropy pool, ...


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