Electrum devs already post "Statement regarding Bitcoin Cash and Electrum" to explain the situation with BTC and BCC.
Statement regarding Bitcoin Cash and Electrum
=============================================
July 26th, 2017.
Electrum is a Bitcoin wallet created by Thomas Voegtlin in 2011.
Electrum is distributed by Electrum Technologies GmbH, a company
registered in Germany, using the website
https://electrum.orgMultiple chain validation
-------------------------
Electrum is a SPV wallet, which means that it verifies and stores a
sequence of block headers sent by the Bitcoin network, and uses these
headers to verify that transactions are in the Bitcoin blockchain.
A new feature in Electrum 2.9 is Multiple Chain Validation
(MCV). Instead of validating a single sequence of block headers,
Electrum 2.9 validates a tree of headers, sent by Electrum servers
that may follow different branches of a fork in the Bitcoin
blockchain.
The purpose of MCV is to detect blockchain forks that would otherwise
be invisible to the classical SPV model, and to let users choose
between branches of such a fork. In particular, this feature has been
designed to deal with the BIP148 soft fork, or the Segwit2x block size
increase.
However, 'Multiple Chain Validation' still includes 'Validation'. In
particular, it assumes that both branches of a fork are valid from the
perspective of a SPV wallet, because they both follow the Bitcoin
rules.
Bitcoin Cash (BCC) is a hard fork that changes the difficulty rules of
Bitcoin. Therefore, SPV wallets written for Bitcoin will reject the
block headers of a BCC fork, and so will Electrum. This means that
Electrum will reject block headers sent by Electrum server running
Bitcoin Cash, and that users will not be able to send and receive BCC
using Electrum.
Would it be possible to add support for Bitcoin Cash in Electrum?
-----------------------------------------------------------------
It would be possible to support BCC in Electrum, by modifying the
difficulty rules we use for block headers validation, and the
transaction creation rules. There are already forks of Electrum doing
that.
However, the headers validation rules of BCC are strictly less secure
than those of Bitcoin. Therefore, it would not be possible to use the
same rules for both chains in Electrum, without significantly lowering
the security of validation of legit Bitcoin transactions.
Thus, in order to safely support both Bitcoin and BCC in the same
Electrum client, one would need to implement two separate sets of
headers validation rules. This is clearly out of the scope of multiple
chain validation. Again, the purpose of MCV is to protect users from
blockchain forks that are not detectable by the classical SPV model,
such as a block size increase.
How to redeem my BCC?
---------------------
BCC wallets will require you to import your seed or your private keys,
which can be exported from Electrum. Doing so will expose all your
Bitcoin funds associated with that seed to the BCC wallet you decide
to use.
Therefore, *after* the BCC fork, but *before* you enter a seed or
private key in a BCC wallet, you should move all your funds to a new
Electrum wallet, with a new seed. You will still be able to use the
old seed or private key with BCC, because BCC has replay
protection. Wait until your funds are confirmed in your new Bitcoin
wallet, before you enter the old private key in a BCC wallet. This
will protect your BTC funds from rogue/untrusted software.
About Electrum Cash
-------------------
The name "Electrum" has been visible on bitcoincash.org and
electrumcash.org, with a modified version of our logo. The use of our
name and logo constitutes a trademark infringement.
We have never enforced our trademark against altcoin versions of
Electrum (such as Litecoin, etc), because we consider that users of
these altcoins are well aware of the distinction between Bitcoin and
their coin, and that they cannot be harmed by that confusion. However,
we do not agree with the use of the Electrum name in the context of a
Bitcoin fork, because it suggests that we endorse that fork, and that
we also endorse that wallet.
We reserve ourselves the right to use the name Electrum for a Bitcoin
Cash wallet, should we decide to publish one in the future.
And they answer how to save your BTC.
