Category: bitcoin
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PoolJacking: easy 51% attacks against Bitcoin and Ethereum
With the recent Ethereum Classic double-spend attack, I decided to finally write this post about an existing vulnerability in Bitcoin and Ethereum. The attack vector has been used in the past to steal a small amount of Bitcoin, but it can be used more cleverly to pull off 51% attacks and double-spend an unbounded amount of…
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Bitcoin vulnerability exploited
http://www.wired.com/2014/08/isp-bitcoin-theft/ Looks like this is an implementation of what I described previously. This guy used BGP to route internet traffic to him — the article is light on the technical details but my guess is that he masqueraded as a popular bitcoin pool and gave out orders that benefited him rather than the real pool. The…
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Bitcoin vulnerability
Today seems like a pretty good day to rag on bitcoin, so I thought I’d post about something I’ve been thinking about ever since I experimented with writing my own miner. Since the goal of that project was educational, I went through it in a way that most other people probably don’t: I built a…
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Aside: ASIC conversion
The current state of the Bitcoin mining world seems to revolve around new ASIC-based miners that are coming out, such as from Butterfly Labs. These devices seem to be very profitable investments if you can get your hands on one — this calculator says that the $2,499 50GH/s machine should pay itself off itself off in…
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FPGA Bitcoin Miner: Improvements
In my last post, I talked about how I did a basic conversion of my bitcoin mining script into verilog for an fpga. The next thing to do, of course, was to increase the mining speed. But first, a little more detail about how the miner works: Overview of a Bitcoin miner The whole Bitcoin…
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FPGA Bitcoin Miner: First Implementation
So, now that I have a working UART module and a simple bitcoin miner, it’s time to implement SHA256 functionality. Specifically, I’m going to implement the 512-bit per-chunk part of the algorithm, since that seems like a good level of abstraction. There’s some other stuff the algorithm does, such as setting initial values and padding, but in…
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Bitcoin
I’m not really sure how it started, but all of a sudden (past 24 hours) I’ve become very interested in bitcoin. Not so much in a “I think it’s the future” kind of way, but more a “there’s a lot of interesting stuff going on and it’s a lot of fun.” I think that sums…
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