With the power of aluminum

These arrived from crypto-cards.com yesterday, and they’re fairly delightful: metal cold-storage wallets with the address and encrypted key laser-etched into the anodized surface.

They’re light, sized like business cards and easy to tuck into a wallet, or hide away somewhere. They’re not going to burn and they’re not going to rust, so it seems like they’d last just about forever.

What makes them brilliant, though, is the use of BIP38-encrypted private keys. This is great in several ways:

It’s ok that a third party is manufacturing your wallet for you, because they never handle your actual keys, only your encrypted key.  You generate it yourself using something like this, then just send the already-encrypted key and corresponding address to the manufacturer

You can carry it around with you, and not worry about someone accidentally photographing the key (or stealing it) because, again — encrypted. Then you can use something like Mycelium to spend from cold storage and decrypt on the fly.

As a bonus, if you do lose it, you’ve already created a backup just through the process of ordering, assuming you save the encrypted key somewhere at that point. So, worst case scenario, you can recover the funds that way.

When you think about how complicated a secure wallet project  could be,  it’s hard not to be impressed with what an elegant and inexpensive solution these metal cards represent.

Now I want a blue one.


Water-resistant to a depth of infinity.
Water-resistant to a depth of infinity.

The AntMiner cometh

Some great designs sneak up on you. At first glance, the Bitmain AntMiner S1 might seem unfinished, all rough and caseless with its insides on the outside.

But the AntMiner doesn’t try to be anything that it isn’t. It has no case, since it’s not a consumer product and it’s not meant for the general public. Since it needs to be attached to an external power supply, why pretend that it’s self contained?

Instead of being bolted to a case or frame and hoping they don’t break loose in shipping, the heavy heatsinks are the frame, and the blades and endpieces bolt to them instead. This simplicity earns the AntMiner a gold star for economy of parts: 2 heatsinks with blades bolted to them, 2 endpieces holding them together, 1 fan, 1 TP-Link TL-WR743N.  The result is sturdy and downright elegant.

What's in the box?
What’s in the box?
The heatsinks are part of the frame.
The heatsinks are part of the frame.

For comparison, a  Butterfly Labs Bitforce SC Single is roughly the same size but has 4 fans,  a 4-piece case, and an interior armature with a whole array of tubes and screws to hold the boards, case, heatsinks and fans all in place.  The airflow is byzantine, it sounds like a jet engine and it sill needs to be connected to another computer to run. The AntMiner is almost silent and, at 180GH/s, it’s also 3 times the speed.

It has its own version of OpenWRT with CGMiner built in, much like an Avalon, and connects right to the internet through an ethernet jack. It also has an attachment for a wifi antenna.

The lights are fantastic. On each side, facing outward, is one green LED which pulses at high speed, giving the whole thing the frantic energy of a firing laser cannon.

It makes a plaintive beeping when it can’t connect to the internet, which is a handy notification, but when it wakes me up in the middle of the night I feel like I’ve acquired another needy pet. Most of the time, though, it just purrs warmly.



Delicious Bit-Cards

I received a set of Bit-Cards in the mail today, which I’d eagerly ordered last week. They look like credit cards, but work like somewhat like Casascius coins or another single-use paper wallet, with a hologram hiding the key, and they come in all sorts of denominations.

This is a very polished design, and they’re a pleasure simply to hold.  You can scan the address directly with one QR code, and you can visit a link to their site with information about your particular card with the other.

They profess to generate the keys and subsequently the cards on an off-line computer running custom software, and that they do not save the keys anywhere other than on the cards. Security features include the tamper-evident hologram as well as the multi-layer manufacturing of the card itself, so it is resistant to invasive scanning.

A black layer in the middle of the card makes it harder to discern the key without removing the hologram.
A black layer in the middle of the card makes it harder to discern the key without removing the hologram.


Scratch off the hologram, and the key is readily available to either scan, or type in manually.

This one's all done.
This one’s all done.

The cards are shipped unfunded, and activated manually by the recipient through their online system upon receipt.  The web site is as polished as the cards, from ordering through activation.

The non-denominated wallet-cards are intriguing, but you just have to keep coming back to the question: Why would I trust anyone else with my private key? In the case of a shiny collectible coin, it might seem worth some risk, but for a plastic card that’s a tougher sell, no matter how pretty the card.

Of what practical utility is a premade card with a set denomination of BTC on it, or an offline wallet the key to which has already been handled by someone else? That’s not entirely clear, but Bit-Card.de is at least establishing themselves in this space, and doing so with considerable style.

Non-denominated wallet-cards. (Address obscured.)
Non-denominated wallet-cards. (Address obscured.)

Standard disclaimer: It’s always, to some degree, a bad idea to let anyone else have access to a private key which controls any of your bitcoin wallets; in a sense, it goes counter to the bitcoin system itself. Once someone else has handled the key which controls your funds, you have to trust both that they exercised adequate security procedures while handling your key, and that they have not save copies of your key to exploit at some point in the unforeseen future. While some  (such as Mike Caldwell of Casascius) have established trusted reputations, newer operators can only prove their trustworthiness over time.




I received two separate treasures in the mail today: my first Cascascius coin, and a set of two Lealana 10 Litecoin pieces.

Mike Caldwell has been making physical bitcoins since 2011, and he’s made them many different ways — brass and silver and gold plate, coins and bars (mostly, though, he’s made them from brass). Each coin has a tamper-evident hologram sticker applied to the back, and beneath it is the key that controls the amount of bitcoin denominated on the front, a one-use-only kind of thing. It’s a coin, but it’s also a sort of cannister for the key, and a very elegant sort of cold storage.


When I first heard about them I though it was a bit odd, and seemed counter to the idea of bitcoin. Why take a perfectly good digital currency and turn it right back into a coinlike object? Over time, though, I really warmed to the idea. They’re fun, they’re beautiful, they’re a handy way to publicize bitcoin or give it as a gift, and Caldwell himself has been such a vocal and stalwart supporter of bitcoin and member of the community that he practically imbues them with authenticity by sheer force of will.

In light of the skyrocketing value of bitcoin in 2013, he’s introduced a .5 BTC piece, and also seems to have focused his efforts on the .999 silver coins (there’s a 1 BTC denomination as well), which suits me fine since the silver makes for a very pretty coin.

My second treasure is even more eccentric. Physical bitcoins have at least been around for a couple years, but today I also received a set of two 10 litecoin pieces, from Noah Luis in Hawaii and branded under the musical name “Lealana.” They’re the first physical litecoins made en masse and they follow the same general model as the Casascius coins, stamped with a denomination which is only given meaning by the key beneath the hologram. They’re a fun and fringe-y sort of object: will the value of litecoins skyrocket, or will they just go away at some point? Whether they become more valuable or just turn into a good story, these still seem pretty darn collectible to me.

They’re silver, too, but that just seems right for a litecoin coin, since we all know litecoins are silvery.

Lovely Lealana litecoins.
Lovely Lealana litecoins.