Bitcoin Forum

I read this https://bitcoin.stackexchange.com/questions/57419/what-would-happen-if-you-send-bitcoin-btc-to-a-bitcoin-cash-bch-aka-bcc-add

I am not sure about the below:

After the implementation of reply protection, is it not possible to send bitcoin from BTC to BCH network , and vice versa?

It is not possible to send BTC to BCH and vice versa. They are two completely separate coins with their own networks and blockchains. BTC and BCH are completely incompatible.

Please don't write this, as you are misleading users and a lot of people will lose money following this kind of advice. Everyday, a lot of people are losing money because they are sending their BTC to BCH addresses (or BCH to BTC addresses) they don't have private key access like exchanges.

As told by achow101, no, it is not possible to send BTC to BCH or BCH to BTC. Those are completely different and incompatible networks. Addresses were the same at some point on both networks? Yeah, well, be aware that you'll most likely lose your funds if you don't know how things work.

Thank you. Got the point.

This was never possible.
A lot of people confused their BTC/bcash addresses and sent their coins to an address (on the same chain).
This was a problem for exchange deposits, who were only monitoring the corresponding chain for this address.

Replay protection was implemented to distinguish between BTC- and bcash transactions.
Before replay protection it was possible to take a (feshly broadcasted) bcash transaction and broadcast it into the btc network (and vice versa).
This would have led to 'the same' transaction being mined on the other chain.

Just one last remark in this topic, the new BCH address format is completely different than any BTC address format to avoid confusion... I'm not a big BCH fan, but i noticed this the last time i wanted to see if i had any unspent outputs on the BCH network left.

For example, my BTC address 1MocACiWLM8bYn8pCrYjy6uHq4U3CkxLaa is BCH address qrjr9lakau9au6t272w2z0wn0syzffqgyv89sgzct3 (eventough, the "legacy" address format is still valid for BCH)

i see, the BCH address format has changed.

i kind of think that if i have privates keys on both BTC and BCH, then can replay protection stops me from mining the same transaction twice?

Replay attacks allowed attackers to reuse a transaction from the BTC network to be injected in the BCH network, and vice versa, without using the private keys. But as BCH network changed their transaction format (and are incompatible with BTC transactions), your unspent transactions are now safe.

As far as I can remember, I believe the following spec is required on the BCH network: https://github.com/bitcoincashorg/spec/blob/master/replay-protected-sighash.md (https://github.com/bitcoincashorg/spec/blob/master/replay-protected-sighash.md) (but I didn't check in details).