For DOT holders who did not complete KSM claim steps before the Kusama genesis.
1 Create Kusama address
Install MathWallet Browser Extension http://mathwallet.org
In MathWallet Browser Extension Switch Network to ‘Kusama’
Create a new Kusama address, and finish the backup process
2 Open ‘Claim’ app in Polkadot Web Wallet
Click the blue【Web Wallet】button or visit https://polkadot.js.org/apps/#
In the web wallet left menu click【Setting】, change the config as below, and then click【Save & Reload】
In the web wallet left menu click【Claim Tokens】, select the Kusama address and click ‘Continue’
Copy the text in ‘Sign ETH transaction’
3 Sign the text using ETH wallet
In MathWallet Browser Extension Switch Network to ‘Ethereum’
Select the ETH wallet which contains your DOT token (you will need to import the ETH wallet to MathWallet Browser Extension first)
Visit:
https://mycrypto.com/sign-and-verify-message/sign
Click the ‘Web3’ button for login
Paste the text you got in the Polkadot web wallet, and then click ‘Sign Message’
In the popup window click ‘Confirm’
Copy the text in Signature
4 Back to Kusama wallet and finish the claim process
In MathWallet Browser Extension Switch Network to ‘Kusama’ gain
And paste the text you got after the Signature into the Polkadot web wallet
Click ‘Confirm claim’, and the page will show the KSM number you can claim
Click ‘Redeem’ to finish the claim process