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Probability of typing a wrong Bitcoin address
39 ibobev 19 8/29/2025, 9:28:50 AM johndcook.com ↗
With that said the point stands that the likelihood of sending bitcoin to an unintended address due to a typo is very small. It's not as small as the article suggests, but it's still basically impossible (about 1 in 4.3 billion for a single character typo).
Perhaps the irony is that if you do happen to send bitcoin to an unintended address, you have a much greater chance of recovering it if that address belongs to a real person and is in use. If the address is not in use, then for all intents and purposes that bitcoin is lost forever.
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[1] https://github.com/CoinFabrik/ClipboardShield
Not quite. More modern addresses have 30 bit checksums (so not at least 32 bits!), but rather than being a truncated cryptographic hash the check digits are a BCH code that guarantees any 4 or fewer substitution or transposition errors will always be detected (or 5 bitflips IIRC)... along with one in a billion or better detection of other kinds of errors.
So although the newer formats provides somewhat less protection against wildly incorrect, the protection against likely errors is much greater. The newer addresses are also case insensitive which was the biggest source of transcription errors in most contexts before.
Beyond being better for real errors the use of a error correction code also makes it impossible to intentionally generate 'fragile' addresses where there does exist a one character typo which is a valid address. It also makes it practical for wallet software to highlight the position of a likely typo, which can greatly speed things up when fixing a mistake. (The spec strenuously cautions against correcting errors, because any correction undermines detection strength).
And as hleszek's comment says, existing addresses don't help, generally addresses should not be reused-- they're not accounts, reusing addresses doesn't make the system work better. Early on in Bitcoin's life people created a scheme for shortened addresses where you used truncated addresses that were unmapped to the first user of that prefix. This obviously bad idea ran into immediate spoofing problems, and people quickly learned better.
> but address typos are not a major concern.
Yeah though malware that substitutes addresses in clipboards and copying the WRONG address are both real risks.
What you also might have heard is advice about _Ethereum_, which in spite of being created long after Bitcoin has addresses with no meaningful checksum and which has caused quite significant losses. (There is an optional very weak checksum using mixed case hex, but AFAICT it's not widely used).
In any case, a fork of Bitcoin with bigger blocks has existed for years and the market doesn't prefer it despite all the big names and companies hyping it up at the time of the split.
Satoshi left Bitcoin so there wouldn't be an appeal to authority so maybe your argument isn't as strong as you think it is.
Sure, but if someone can change your QR code, they could change the address just as easily. With websites you can see if the URL looks like something legitimate, so URLs are slightly better, but Bitcoin addresses are just a long random string, so being able to see the address wouldn't actually help anything.
When done correctly by a payment processor, the receiver's QR code for a Bitcoin payment varies for every transaction. It completely eliminates the risk of mistyping it. Granted, malware could replace it, but replacing it is a lot harder than replacing a simple address.