Revisiting the Security of Bitcoin

Recently, the news that a pig-butchering gang in Cambodia had 120,000 bitcoins confiscated by the U.S. government spread across the internet. Many people's first reaction to this news was, "Is Bitcoin still safe?" Some even thought, "Bitcoin is finished."

Several of my friends asked me this question, and readers mentioned it in the comments below the article.

Regarding this issue, I think Wu's article "The 120,000 Bitcoins of the Cambodian Pig-Butchering Boss: How Were They Confiscated by the U.S. Government?" (full text can be found in the reference link at the end of the article) explains it quite clearly.

If we summarize the content of the article, it can be distilled to:

The private key of the wallet storing the bitcoins had obvious vulnerabilities at the time of its generation, and the root of this vulnerability lies in the insufficient randomness of the random number. Alternatively, the wallet holder may have left some information about the private key off-chain that was obtained by the U.S. government.

If the holder leaked the information themselves, then the issue lies with the holder and is unrelated to the security of the private key.

If the security of the private key itself is insufficient, then there is a problem with the wallet software that generated the private key: its random number is not random enough—this is something we should pay attention to.

In theory, the random numbers generated by current computing systems are not truly random but pseudo-random. However, with advancements in technology, many methods have been invented to make these numbers as close to true randomness as possible.

If the random numbers used in key generation are too "pseudo," it will leave obvious vulnerabilities for attackers to guess what the key is, thereby stealing the coins in the wallet.

When I worked at a blockchain company, an engineer once playfully used a special tool to generate a large number of Ethereum wallet addresses containing auspicious numbers, and then gave them to many colleagues.

Wallets like this do not have keys generated from numbers close to true randomness, so their keys are very insecure and easily compromised.

Despite this, several colleagues actually deposited some Ethereum into these wallets to make transactions. They certainly knew these wallets were not secure but still used them for transactions. This was purely for fun, especially to show off to outsiders.

A more common example can illustrate how important the randomness of private keys is.

We have all applied for email accounts. When applying for an email account, we are required to set a password, and many email services require the password to be at least 8 characters long, consisting of a combination of uppercase and lowercase letters, special characters, and numbers.

If we set the password this way, generally speaking, the longer the password, the harder it is to crack.

But some people do not follow this rule; they set all characters to be the same letter, number, or special character, and inadvertently reveal this habit of setting passwords.

In such cases, it becomes very easy for an attacker to compromise their email.

If any readers were early adopters of this ecosystem, they might remember:

Early wallets required users to randomly move the mouse on the screen when generating seed phrases (keys). The purpose of this was to increase the randomness of the keys through the user's random actions.

Now, many wallets no longer require this because better user experiences and methods for obtaining randomness have been developed.

So generally speaking, if you are using a reputable, established wallet brand, the private keys they generate are relatively secure, and ordinary users do not need to worry too much.

In fact, for tech-savvy players, it is even possible to generate highly random keys using physical methods, which provides even more reassurance.

In summary, this case is merely an isolated incident; the issues it reflects are more about human operation or wallet software problems rather than the security of the Bitcoin mechanism itself.

Overall, Bitcoin, Ethereum, and even wallets strictly based on cryptographic generation remain secure.