So if you have an address with coins in it that uses an uncompressed public key (preceeded by a "04") then how can coins from that wallet be utilized with a network that doesn't allow such public keys? Compressing the public key changes the relevant wallet address and would prevent one from being able to access one's coins at that point. Does bitcoin still allow the "04"? I've read, it seems, that bitcoin cash does not.

  • seems bitcoin cash does not That would really surprise me. Do you have a link to where you read that?
    – Nick ODell
    Aug 17, 2017 at 2:37
  • I hope I misread it, but it is here: github.com/bitcoin/bips/blob/master/…. That was the link I got when I asked for how to make a tx for bitcoin cash, and instead of a full answer, I got that link.
    – Mine
    Aug 17, 2017 at 4:18
  • Yeah, but that's just for segwit.
    – Nick ODell
    Aug 17, 2017 at 4:20
  • Doesn't bitcoin cash use segwit and won't bitcoin be using it soon as well? thereby denying the use of addresses made with uncompressed addresses? referenced question; bitcoin.stackexchange.com/questions/58012/…
    – Mine
    Aug 17, 2017 at 4:21
  • coindesk.com/… information here, if it is correct, raises the spectre that segwit may become required. It referenced "reject a block that wasn't signaling for SegWit" regarding miners.
    – Mine
    Aug 17, 2017 at 4:26

1 Answer 1


Uncompressed keys are only disallowed for segwit output types. Since segwit outputs are a completely new type of output that requires new addresses (and a new address type eventually), there won't be any effect on your current addresses and keys. Non-segwit transactions and outputs can still exist and will happen. These transactions will work in the exact same way they do now; you won't be using segwit (and thus not allowed to use uncompressed keys) unless you explicitly go to use it.

Bitcoin Cash does not have segwit, so they are not invalidating uncompressed keys. The only part of BIP 143 that Bitcoin Cash is using is the sighashing algorithm.

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