prepare: Add backwards compatibility mode for DASH wallets.

testing notes:
gist.github.com/tecnovert/627f67b7d04746f79c3e9e975458139e

basicswap/interface/dash.py

@@ -25,6 +25,8 @@ class DASHInterface(BTCInterface):
         self._wallet_passphrase = ''
         self._have_checked_seed = False
 
+        self._wallet_v20_compatible = False if not swap_client else swap_client.getChainClientSettings(self.coin_type()).get('wallet_v20_compatible', False)
+
     def decodeAddress(self, address: str) -> bytes:
         return decodeAddress(address)[1:]
 
@@ -32,6 +34,33 @@ class DASHInterface(BTCInterface):
         hdseed: str = self.rpc_wallet('dumphdinfo')['hdseed']
         return self.getSeedHash(bytes.fromhex(hdseed)).hex()
 
+    def entropyToMnemonic(self, key: bytes) -> None:
+        return Mnemonic('english').to_mnemonic(key)
+
+    def initialiseWallet(self, key_bytes: bytes) -> None:
+        if self._wallet_v20_compatible:
+            self._log.warning(f'Generating wallet compatible with v20 seed.')
+            words = self.entropyToMnemonic(key_bytes)
+            mnemonic_passphrase = ''
+            self.rpc_wallet('upgradetohd', [words, mnemonic_passphrase, self._wallet_passphrase])
+            self._have_checked_seed = False
+            if self._wallet_passphrase != '':
+                self.unlockWallet(self._wallet_passphrase)
+            return
+
+        key_wif = self.encodeKey(key_bytes)
+        self.rpc_wallet('sethdseed', [True, key_wif])
+
+    def checkExpectedSeed(self, expect_seedid: str) -> bool:
+        self._expect_seedid_hex = expect_seedid
+        rv = self.rpc_wallet('dumphdinfo')
+        if rv['mnemonic'] != '':
+            entropy = Mnemonic('english').to_entropy(rv['mnemonic'].split(' '))
+            entropy_hash = self.getAddressHashFromKey(entropy)[::-1].hex()
+            return expect_seedid == entropy_hash
+        else:
+            return expect_seedid == self.getWalletSeedID()
+
     def withdrawCoin(self, value, addr_to, subfee):
         params = [addr_to, value, '', '', subfee, False, False, self._conf_target]
         return self.rpc_wallet('sendtoaddress', params)

bin/basicswap_prepare.py

@@ -1256,6 +1256,7 @@ def printHelp():
     print('--keysdirpath            Speed up tests by preloading all PGP keys in directory.')
     print('--noreleasesizecheck     If unset the size of existing core release files will be compared to their size at their download url.')
     print('--redownloadreleases     If set core release files will be redownloaded.')
+    print('--dashv20compatible      Generate the same DASH wallet seed as for DASH v20 - Use only when importing an existing seed.')
 
     active_coins = []
     for coin_name in known_coins.keys():
@@ -1588,6 +1589,9 @@ def main():
         if name == 'initwalletsonly':
             initwalletsonly = True
             continue
+        if name == 'dashv20compatible':
+            extra_opts['dash_v20_compatible'] = True
+            continue
         if len(s) == 2:
             if name == 'datadir':
                 data_dir = os.path.expanduser(s[1].strip('"'))
@@ -1933,6 +1937,9 @@ def main():
     chainclients['monero']['walletsdir'] = os.getenv('XMR_WALLETS_DIR', chainclients['monero']['datadir'])
     chainclients['wownero']['walletsdir'] = os.getenv('WOW_WALLETS_DIR', chainclients['wownero']['datadir'])
 
+    if extra_opts.get('dash_v20_compatible', False):
+        chainclients['dash']['wallet_v20_compatible'] = True
+
     if initwalletsonly:
         logger.info('Initialising wallets')
         settings = load_config(config_path)

doc/coins/dash.md

@@ -0,0 +1,14 @@
+## DASH Notes
+
+### Importing wallets created with DASH version <21
+
+
+From version 21 DASH core can use the sethdseed rpc command.
+The old method to import a seed used the DASH specific upgradetohd rpc command.
+
+
+To import a wallet created on DASH v20 use basicswap-prepare with the --dashv20compatible flag.
+
+Example:
+
+    basicswap-prepare --withcoins=dash --particl_mnemonic="..." --dashv20compatible