create polkadot-js extension backup file

polkadot-extension-backup.ts

import { fromHex, utf16StrToUtf8Bytes } from "@unstoppablejs/utils";            
import { jsonEncrypt } from "@polkadot/util-crypto";                            
import { createPair, Keyring } from "@polkadot/keyring";                        
                                                                                
const keyToBytes = (input: string | Uint8Array): Uint8Array =>                  
  typeof input === "string" ? fromHex(input) : input;                           
                                                                                
export function createBackUpFileContent(                                        
  addresses: Array<{                                                            
    name: string;                                                               
    password: string;                                                           
    publicKey: string | Uint8Array;                                             
    privateKey: string | Uint8Array;                                            
  }>,                                                                           
  filePassword: string                                                          
) {                                                                             
  const keyring = new Keyring();                                                
  const pairs = addresses.map(({ name, publicKey, privateKey }) =>              
    createPair(                                                                 
      { toSS58: keyring.encodeAddress, type: "sr25519" },                       
      { publicKey: keyToBytes(publicKey), secretKey: keyToBytes(privateKey) },  
      {                                                                         
        name,                                                                   
        whenCreated: Date.now(),                                                
      }                                                                         
    )                                                                           
  );                                                                            
                                                                                
  const encryptedPairs = utf16StrToUtf8Bytes(                                   
    JSON.stringify(                                                             
      pairs.map((pair, idx) => pair.toJson(addresses[idx].password))            
    )                                                                           
  );                                                                            
                                                                                
  return {                                                                      
    ...jsonEncrypt(encryptedPairs, ["batch-pkcs8"], filePassword),              
    accounts: pairs.map(({ address, meta }) => ({ address, meta })),            
  };                                                                            
}                                                                               
                                                                                
// I'm definitely not using these keys... Well, unless someone else uses them :P
const keys: Array<[privateKey: string, publicKey: string]> = [                  
  [                                                                             
    "0x47fade4e38060d1c2f818aef6a563d7c5daac80b8c70c856feb1cfeed3f04c84",       
    "0xaec7317630727847e5248c32ecc225a5e3c575685754c762a7748b2040aaab4d",       
  ],                                                                            
  [                                                                             
    "0x97c75e800b8ec87653ac8094ae761a55492c54564b2a1b2c4a69833143463067",       
    "0x34bcac21b7658e9ad90732bb5c18326aaff13b26ab934b3c83fdda7e7f94a322",       
  ],                                                                            
  [                                                                             
    "0x430120a7b4d2b2a970f5654f973669c9c7d66a46d9f12d8ad72c85e05ed528f8",       
    "0xf648366356aa719dd19a35c463a663cf8aa614e77eb4fc6174395787ec2d6130",       
  ],                                                                            
  [                                                                             
    "0xb77d6c13916ea41753c72089470d821f5fe09974f69058dbd7a3569f66262f39",       
    "0xb660610f3c021bf91344023090b66891fe97c37d2e01541d4314f446abb0c011",       
  ],                                                                            
];                                                                              
                                                                                
const addresses = keys.map(([privateKey, publicKey], idx) => ({                 
  publicKey,                                                                    
  privateKey,                                                                   
  name: `CompromisedKey_${idx}`,                                                
  password: `weakPassword${idx}`,                                               
}));                                                                            
                                                                                
console.log(                                                                    
  JSON.stringify(createBackUpFileContent(addresses, "ThisIsDangerousAF!"))      
);