<p>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.</p>

<p>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.</p>

CC BY-SA 3.0
2017-08-17T06:37:34.990Z
2017-08-17T06:37:34.990Z
Ava Chow
<p>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.</p>

CC BY-SA 3.0
2017-08-17T02:37:36.713Z
`seems bitcoin cash does not` That would really surprise me. Do you have a link to where you read that?
Nick ODell
CC BY-SA 3.0
2017-08-17T04:18:51.140Z
I hope I misread it, but it is here:  https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki#restrictions-on-public-key-type.  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
CC BY-SA 3.0
2017-08-17T04:20:38.933Z
Yeah, but that's just for segwit.
Nick ODell
CC BY-SA 3.0
2017-08-17T04:21:57.077Z
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; https://bitcoin.stackexchange.com/questions/58012/what-is-the-exact-difference-between-a-bitcoin-and-bitcoin-cash-raw-transaction
Mine
CC BY-SA 3.0
2017-08-17T04:26:31.320Z
https://www.coindesk.com/whats-left-before-segwit-goes-live-bitcoins-path-more-capacity/ 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
CC BY-SA 3.0
2017-08-17T04:35:00.990Z
UASF and the hardfork Bitcoin Cash implements are mutually exclusive.
Nick ODell
CC BY-SA 3.0
2017-08-17T05:05:00.223Z
I don't know what UASF means, but that article is in reference to bitcoin, not bitcoin cash
Mine
CC BY-SA 3.0
2017-08-17T05:09:32.743Z
Let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/63970/discussion-between-nick-odell-and-mine).
Nick ODell
<public-key><signature><ecdsa>
If newer versions of bitcoin and or bitcoin cash don't allow 0x04 uncompressed public keys, what do you do if you have an address based on one?
Mine
# If newer versions of bitcoin and or bitcoin cash don't allow 0x04 uncompressed public keys, what do you do if you have an address based on one?

(Asked by: username_0 on 2017-08-17)

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.

**Tags:** public-key, signature, ecdsa

> **Comments:**
> **username_1**: `seems bitcoin cash does not` That would really surprise me. Do you have a link to where you read that?  
> **username_0**: I hope I misread it, but it is here:  https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki#restrictions-on-public-key-type.  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.  
> **username_1**: Yeah, but that's just for segwit.  
> **username_0**: 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; https://bitcoin.stackexchange.com/questions/58012/what-is-the-exact-difference-between-a-bitcoin-and-bitcoin-cash-raw-transaction  
> **username_0**: https://www.coindesk.com/whats-left-before-segwit-goes-live-bitcoins-path-more-capacity/ 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.  
> **username_1**: UASF and the hardfork Bitcoin Cash implements are mutually exclusive.  
> **username_0**: I don't know what UASF means, but that article is in reference to bitcoin, not bitcoin cash  
> **username_1**: Let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/63970/discussion-between-username_1-username_1-and-username_0).  

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## 1 answers

### Answer by username_2 on 2017-08-17. Score: 1 | Accepted answer

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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