Is it okay to use the same Bitcoin address multiple times, ignoring privacy concerns? I read somewhere that if the nonce k used for the ECDSA signature isn’t random, it could expose your private key. Is that a real-world issue?
You can definitely reuse addresses, no biggie. In reality, no one can figure out your private key just because you’re using the same public key. The real issue is privacy, since people can see you adding funds to the same address. Mixing it up later can help hide your balance.
If privacy isn’t your concern, sure, reuse addresses. But it’s not great for privacy overall. Using change addresses can actually enhance your privacy. Check out some tips here.
True, if someone knows your nonce, they can derive your private key from the signature. But Bitcoin Core is open-source, and such bugs usually get caught early on. The address reuse issue is often exaggerated; the real risk is if you keep reusing non-random nonces.
Exactly. Bitcoin Core uses pseudo-random values for that reason. Reusing an address doesn’t mean every transaction will use the same nonce. Just because the address is the same doesn’t mean the k value is reused when spending.
Wallets like Bitcoin Core encourage new addresses every time you hit receive. But some argue it’s just about privacy. I think they need to revamp the receive tab UI; the old one was way better for managing new and old addresses.
You nailed it. The UI should push for new addresses for better privacy. Is it wiser to have a default that helps users who might not get privacy concepts, or let them reuse addresses and risk exposure?
If your k is random but reused, it can leak your private key if you sign multiple transactions with it. If it’s weak, it can leak on the first use. But Bitcoin Core has never had that issue; most wallets now use RFC6979 to securely derive k.
No security issues with address reuse in Bitcoin Core since it doesn’t use a predictable nonce. All address types get a randomly generated nonce. Even those with deterministic nonces likely use RFC6979, which is pretty secure.
If privacy isn’t a worry for you, go ahead. But smart address management is key. Watch out for fees too; consolidating when they’re low is smart. Silent Payments could be worth checking out for fresh addresses.
The R values are linked to the k nonce. You get R by multiplying k with the secp256k1 generator point. The Android wallet blunder is a prime example; that wouldn’t happen with a well-built wallet. Bitcoin Core has used deterministic nonces since version 0.10.0.
Blockchain.info was a major disaster in wallet history! They used random.org for k values in a really dumb way. When random.org changed its system, everyone using that wallet ended up with the same k value because the code didn’t handle errors right.