Bitcoin network has encountered several major bugs since its inception, but the most intriguing one was discovered back in 2010. The bug was first spotted by the core developer Jeff Garzik, who noticed that the Bitcoin Block 74638 has quite strange transaction outputs. Each transaction on the block stood at a whopping 92233720368.54 BTC apiece.
Within one hour of the discovery, the community was abuzz with the latest discovery and one of the users started a thread titled, “overflow bug serious” and people started to take notice. The integer overflow bug led to the creation of 184 billion Bitcoin out of thin air. Bitcoin wiki has listed a total of 40 bugs in the network of different forms, but none came close to the integer overflow one.
The level of attention that the bug received was due to the fact that Bitcoin has a total cap of 21 million tokens and the new bug added 184 billion tokens to the existing cap causing a sense of alarm among the developers. The issue arose due to a negative integer outflow which caused the transaction value to exceed by that much. One of the forum users explained,
“Normally the inputs are equal to the outputs of a transaction. The exception is when there is a ‘fee’ charged for the transaction. The net allows anyone to voluntarily pay any amount for a fee. So when the sum was negative the difference from the input looked like a fee. It slipped thru all the checks.”
The Exploits Followed the Bug
An unknown attacker discovered the bug and used the vulnerability to generate a ridiculous amount of Bitcoin. However, if the attacker would have been sane enough to generate a modest amount the impact could have been disastrous, not only financially but psychologically too.
Bitcoin was relatively new at that point in time and thus such a great vulnerability followed by an attack could have seen an end of the Bitcoin phenomenon much earlier. However, the developers came into action quickly and the patch for the bug was implemented within 2 hours of the discovery of the bug.
Later all the transactions from the block 74638 were discarded. Satoshi was at the helm when the bug was discovered and he was active on the forums tracking the events following the discovery of the bug. Satoshi posted several times updating the community over the progress made in eradicating the bug. He wrote on one of the forums,
“Once more than 50% of the node power is upgraded and the good chain overtakes the bad, the 0.3.10 nodes will make it hard for any bad transactions to get any confirmations,”
Satoshi later left his project which started a revolution of sorts in the hands of the community and proved the point of decentralization to the world.
The bug on the Bitcoin block 74638 was caused due to an integer overflow and was only discovered when an unknown attacker used the opportunity to generate ridiculous sums of Bitcoin. However, since the bitcoin community is decentralized, the bug was detected and a fix patch was put in place within 2 hours.
Satoshi was a part of the Bitcoin network at that point in time, and he kept the community informed on the progress. The bug could have caused havoc on the Bitcoin network if it wouldn’t have been discovered early and probably Bitcoin could have never been this successful as the number of people wanting you it to fail were too high.