Oleg Andreev



Software designer with focus on user experience and security.

You may start with my selection of articles on Bitcoin.

Переводы некоторых статей на русский.


Product architect at Chain.

Author of Gitbox version control app.

Author of CoreBitcoin, a Bitcoin toolkit for Objective-C.

Author of BTCRuby, a Bitcoin toolkit for Ruby.

Former lead dev of FunGolf GPS, the best golfer's personal assistant.


I am happy to give you an interview or provide you with a consultation.
I am very interested in innovative ways to secure property and personal interactions: all the way from cryptography to user interfaces. I am not interested in trading, mining or building exchanges.

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June 5

Today I’ve timestamped my secret source code with Bitcoin

I have some interesting ideas on how to make awesome Bitcoin wallet app for OS X (and for iOS too if Apple allows). I will release source code with a beta version, but before that I want to make sure no one will claim that I took someone’s idea (I have some interesting sketches, app icon, security papers and a business plan). To do that I timestamped the latest git commit in the blockchain.

Here is the commit: e09d665d7ffd70d5d6b672305e744916c3c827e9

To verify the timestamp, do the following:

  1. Go to brainwallet.org
  2. Select “Secret Exponent” and paste there commit ID e09d665…
  3. See the resulting address: 1AAX6PJEm2FLXT6RoRAUzNFmFHnueFGGs1.
  4. Go to blockchain.info and find this address.
  5. Select the very first transaction: 687c24d…
  6. Check that transaction is included in block 239851. Timestamp is 2013-06-05 07:46:41.

When I release the source code anyone on the planet can independently verify that all my documents were created before June 5, 2013.

Note that I used my git commit ID as a secret key, not as an address. This means that bitcoins are not destroyed, anyone who knows my commit ID can sign a transaction spending money on this address. Obviously, I could recover my BTC before announcing the secret key, but decided to have some fun and post in Twitter for anyone to pick up the money (about 5 cents). Indeed, within an hour someone took all the coins.

This method does not rely neither on brainwallet.org, nor on blockchain.info. You can use your own software to perform the same tasks. (It was the easiest way for me, though.)

In the end, I’ve spend only 15 cents for recording my data with a timestamp. Now all I need is 50000 recent blockchain headers (80 bytes each) and a full block with my transaction (225 Kb). That amounts to just 4 Mb of data. I can now take this data on a USB drive and prove anywhere to anyone that my data existed on that particular date. Because the total difficulty of proof-of-work depicted in the block headers is so huge, it would require thousands of supercomputers working one year non-stop to forge the timestamp.