Miniscript

docs/miniscript.md

@@ -0,0 +1,24 @@
+# Miniscript
+
+**COLDCARD<sup>&reg;</sup>** Mk4 experimental `EDGE` versions
+support Miniscript and MiniTapscript.
+
+## Import/Export
+
+* `Settings` -> `Miniscript` -> `Import from file`
+* only [descriptors](https://github.com/bitcoin/bips/blob/master/bip-0380.mediawiki) allowed for import
+* `Settings` -> `Miniscript` -> `<name>` -> `Descriptors`
+* only [descriptors](https://github.com/bitcoin/bips/blob/master/bip-0380.mediawiki) are exported
+
+## Address Explorer
+
+Same as with basic multisig. After miniscript wallet is imported, 
+item with `<name>` is added to `Address Explorer` menu.
+
+
+## Limitations
+* no duplicate keys in miniscript (at least account in origin derivation has to be different)
+* subderivation must be `<0;1>/*` (may be omitted during the import - is implied)
+* only keys with key origin info `[xfp/p/a/t/h]xpub`
+* maximum number of keys allowed in segwit v0 miniscript is 20
+* check MiniTapscript limitations in `docs/taproot.md`

docs/taproot.md

@@ -1,10 +1,9 @@
 # Taproot
 
-**COLDCARD<sup>&reg;</sup>** Mk4 experimental `EDGE` versions will
+**COLDCARD<sup>&reg;</sup>** Mk4 experimental `EDGE` versions
 support Schnorr signatures ([BIP-0340](https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki)), 
 Taproot ([BIP-0341](https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki)) 
-and very limited Tapscript ([BIP-0342](https://github.com/bitcoin/bips/blob/master/bip-0342.mediawiki)) support.
-Tapscript support will get more versatile with future iterations.
+and Tapscript ([BIP-0342](https://github.com/bitcoin/bips/blob/master/bip-0342.mediawiki)) support.
 
 ## Output script (a.k.a address) generation
 
@@ -18,7 +17,11 @@ MUST be generated with above-mentoned methods to be considered change.
 ## Allowed descriptors
 
 1. Single signature wallet without script path: `tr(key)`
-2. Tapscript multisig with internal key and one sortedmulti multisig script: `tr(internal_key, sortedmulti_a(MofN))`
+2. Tapscript multisig with internal key and up to 8 leaf scripts:
+    * `tr(internal_key, sortedmulti_a(2,@0,@1))`
+    * `tr(internal_key, pk(@0))`
+    * `tr(internal_key, {sortedmulti_a(2,@0,@1),pk(@2)})`
+    * `tr(internal_key, {or_d(pk(@0),and_v(v:pkh(@1),older(1000))),pk(@2)})`
 
 ## Provably unspendable internal key
 
@@ -27,24 +30,24 @@ for multisig.
 
 1. use provably unspendable internal key H from [BIP-0341](https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki#constructing-and-spending-taproot-outputs). This way is leaking the information that key path spending is not possible and therefore not recommended privacy-wise.
 
-    `tr(50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0, sortedmulti_a(MofN))`
+    `tr(50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0, sortedmulti_a(2,@0,@1))`
 
 2. use COLDCARD specific placeholder `@` to let HWW pick a fresh integer r in the range 0...n-1 uniformly at random and use `H + rG` as internal key. COLDCARD will not store r and therefore user is not able to prove to other party how the key was generated and whether it is actually unspendable.
 
     `tr(r=@, sortedmulti_a(MofN))`
 
 3. pick a fresh integer r in the range 0...n-1 uniformly at random yourself and provide that in the descriptor. COLDCARD generates internal key with `H + rG`. It is possible to prove to other party that this internal key does not have a known discrete logarithm with respect to G by revealing r to a verifier who can then reconstruct how the internal key was created.
 
-    `tr(r=77ec0c0fdb9733e6a3c753b1374c4a465cba80dff52fc196972640a26dd08b76, sortedmulti_a(MofN))`
+    `tr(r=77ec0c0fdb9733e6a3c753b1374c4a465cba80dff52fc196972640a26dd08b76, sortedmulti_a(2,@0,@1))`
 
 
 ## Limitations
 
 ### Tapscript Limitations
 
-In current version only `TREE` of depth 0 is allowed. Meaning that only one leaf script is allowed 
-and tagged hash of this single leaf script is also a merkle root. Only allowed script (for now) is `sortedmulti_a`.
-Taproot multisig currently has artificial limit of max 32 signers (M=N=32).
+In current version only `TREE` of max depth 4 is allowed (max 8 leaf script allowed).
+Taproot single leaf multisig has artificial limit of max 32 signers (M=N=32).
+Number of keys in taptree is limited to 32.
 
 If Coldcard can sign by both key path and script path - key path has precedence.
 

releases/EdgeChangeLog.md

@@ -7,7 +7,9 @@
 - for experimental use.  DO NOT use for large Bitcoin amounts.
 ```
 
-## 6.0.1X - 2023-0?-??
+## 6.1.0X - 2023-06-19
+- New Feature: Miniscript and MiniTapscript support (`docs/miniscript.md`)
+- Enhancement: Tapscript up to 8 leafs
 - Address explorer display refined slightly (cosmetic)
 
 ## 6.0.0X - 2023-05-12

shared/actions.py

@@ -769,7 +769,7 @@ async def start_login_sequence():
     #
     from ux import idle_logout
     from glob import dis
-    import callgate
+    import callgate, version
 
     if version.mk_num < 4:
         # Block very obsolete versions.

shared/address_explorer.py

@@ -9,19 +9,14 @@
 from menu import MenuSystem, MenuItem
 from public_constants import AFC_BECH32, AF_CLASSIC, AF_P2WPKH, AF_P2WPKH_P2SH, AF_P2TR
 from multisig import MultisigWallet
+from miniscript import MiniScriptWallet
 from uasyncio import sleep_ms
+from ucollections import OrderedDict
 from uhashlib import sha256
-from ubinascii import hexlify as b2a_hex
 from glob import settings
 from auth import write_sig_file
-from utils import addr_fmt_label
+from utils import addr_fmt_label, truncate_address
 
-def truncate_address(addr):
-    # Truncates address to width of screen, replacing middle chars
-    # - 16 chars screen width
-    # - but 2 lost at left (menu arrow, corner arrow)
-    # - want to show not truncated on right side
-    return addr[0:5] + '⋯' + addr[-6:]
 
 class KeypathMenu(MenuSystem):
     def __init__(self, path=None, nl=0):
@@ -201,7 +196,11 @@ async def render(self):
             # if they have MS wallets, add those next
             for ms in MultisigWallet.iter_wallets():
                 if not ms.addr_fmt: continue
-                items.append(MenuItem(ms.name, f=self.pick_multisig, arg=ms))
+                items.append(MenuItem(ms.name, f=self.pick_miniscript, arg=ms))
+
+            # if they have miniscript wallets, add those next
+            for msc in MiniScriptWallet.iter_wallets():
+                items.append(MenuItem(msc.name, f=self.pick_miniscript, arg=msc))
         else:
             items.append(MenuItem("Account: %d" % self.account_num, f=self.change_account))
 
@@ -223,10 +222,10 @@ async def pick_single(self, _1, _2, item):
         settings.put('axi', axi)  # update last clicked address
         await self.show_n_addresses(path, addr_fmt, None)
 
-    async def pick_multisig(self, _1, _2, item):
-        ms_wallet = item.arg
+    async def pick_miniscript(self, _1, _2, item):
+        msc_wallet = item.arg
         settings.put('axi', item.label)       # update last clicked address
-        await self.show_n_addresses(None, None, ms_wallet)
+        await self.show_n_addresses(None, None, msc_wallet)
 
     async def make_custom(self, *a):
         # picking a custom derivation path: makes a tree of menus, with chance
@@ -256,7 +255,15 @@ async def show_n_addresses(self, path, addr_fmt, ms_wallet, start=0, n=10, allow
         from glob import dis, NFC, VD
         import version
 
-        def make_msg(change=0):
+        # speed up UI (do not recalculate addresses in while loop)
+        # cache can only have 2 values external, internal (0,1)
+        _cache = OrderedDict()
+
+        def make_msg(change=0, start=start, n=n):
+            nonlocal _cache
+            if (change, start, n) in _cache:
+                return _cache[(change, start, n)]
+
             export_msg = "Press (1) to save Address summary file to SD Card."
             if version.has_fatram and not ms_wallet:
                 export_msg += " Press (2) to view QR Codes."
@@ -288,26 +295,8 @@ def make_msg(change=0):
                 # but show enough they can verify addrs shown elsewhere.
                 # - makes a redeem script
                 # - converts into addr
-                # - assumes 0/0 is first address.
-                for (i, paths, addr, script, ik, ikp) in ms_wallet.yield_addresses(start, n, change_idx=change):
-                    if i == 0 and ik:
-                        msg += "Taproot internal key:\n\n"
-                        if ikp:
-                            msg += ikp + "\n\n"
-                        else:
-                            msg += '%s (provably unspendable)\n\n' % ik
-
-                        if ms_wallet.N <= 4:
-                            msg += "Taproot tree keys:\n\n"
-
-                    if i == 0 and ms_wallet.N <= 4:
-                        msg += '\n'.join(paths) + '\n =>\n'
-                    else:
-                        msg += '.../%d/%d =>\n' % (change, i)
-
-                    addrs.append(addr)
-                    msg += truncate_address(addr) + '\n\n'
-                    dis.progress_bar_show(i/n)
+                # - assumes <0;1>/0 is first address.
+                msg, addrs = ms_wallet.make_addresses_msg(msg, start, n, change)
 
             else:
                 # single-singer wallets
@@ -329,10 +318,15 @@ def make_msg(change=0):
             if n > 1:
                 msg += "Press (9) to see next group, (7) to go back. X to quit."
 
+            if len(_cache) < 4:
+                _cache[(change, start, n)] = (msg, addrs)
+            else:
+                # LIFO
+                _cache = OrderedDict(list(_cache.items())[:-1])
             return msg, addrs
 
-        msg, addrs = make_msg()
         change = 0
+        msg, addrs = make_msg(change, start)
         while 1:
             ch = await ux_show_story(msg, escape='1234679')
 
@@ -380,31 +374,13 @@ def make_msg(change=0):
             else:
                 continue        # 3 in non-NFC mode
 
-            msg, addrs = make_msg(change)
+            msg, addrs = make_msg(change, start, n)
 
 def generate_address_csv(path, addr_fmt, ms_wallet, account_num, n, start=0, change=0):
     # Produce CSV file contents as a generator
-
     if ms_wallet:
-        # For multisig, include redeem script and derivation for each signer
-        yield '"' + '","'.join(['Index', 'Payment Address',
-                                '%s (%d of %d)' % (
-                                    "Leaf Script" if ms_wallet.internal_key else "Redeem Script",
-                                    ms_wallet.M, ms_wallet.N
-                                )]
-                               + (['Derivation'] * ms_wallet.N)
-                               + ["Taproot Internal Key"] if ms_wallet.internal_key else []
-                               ) + '"\n'
-
-        for (idx, derivs, addr, script, ik, ikp) in ms_wallet.yield_addresses(start, n, change_idx=change):
-            ln = '%d,"%s","%s","' % (idx, addr, b2a_hex(script).decode())
-            ln += '","'.join(derivs)
-            if ik:
-                # internal xonly key with its derivation (if any)
-                ln += '","%s' % (ikp + ik)
-            ln += '"\n'
-
-            yield ln
+        for line in ms_wallet.generate_address_csv(start, n, change):
+            yield line
 
         return
 

shared/auth.py

@@ -1391,17 +1391,15 @@ def usb_show_address(addr_format, subpath):
     return active_request.address
 
 
-class NewEnrollRequest(UserAuthorizedAction):
-    def __init__(self, ms, auto_export=False, bsms_index=None):
+class NewMiniscriptEnrollRequest(UserAuthorizedAction):
+    def __init__(self, msc, auto_export=False, bsms_index=None):
         super().__init__()
-        self.wallet = ms
+        self.wallet = msc
         self.auto_export = auto_export
         self.bsms_index = bsms_index
 
-        # self.result ... will be re-serialized xpub
-
     async def interact(self):
-        from multisig import MultisigOutOfSpace
+        from wallet_base import WalletOutOfSpace
 
         ms = self.wallet
         try:
@@ -1413,23 +1411,23 @@ async def interact(self):
                     from bsms import BSMSSettings
                     BSMSSettings.signer_delete(self.bsms_index)
                 if self.auto_export:
-                    # save cosigner details now too 
-                    await ms.export_wallet_file('created on', 
-    "\n\nImport that file onto the other Coldcards involved with this multisig wallet.")
+                    # save cosigner details now too
+                    await ms.export_wallet_file('created on',
+                                                "\n\nImport that file onto the other Coldcards involved with this multisig wallet.")
                     await ms.export_electrum()
 
             else:
                 # they don't want to!
                 self.refused = True
                 await ux_dramatic_pause("Refused.", 2)
 
-        except MultisigOutOfSpace:
+        except WalletOutOfSpace:
             return await self.failure('No space left')
         except BaseException as exc:
             self.failed = "Exception"
             sys.print_exception(exc)
         finally:
-            UserAuthorizedAction.cleanup()      # because no results to store
+            UserAuthorizedAction.cleanup()  # because no results to store
             if self.bsms_index is not None:
                 # bsms special case, get him back to multisig menu
                 from ux import the_ux, restore_menu
@@ -1445,9 +1443,10 @@ async def interact(self):
             else:
                 self.pop_menu()
 
-def maybe_enroll_xpub(sf_len=None, config=None, name=None, ux_reset=False, bsms_index=None):
+def maybe_enroll_xpub(sf_len=None, config=None, name=None, ux_reset=False, bsms_index=None, miniscript=False):
     # Offer to import (enroll) a new multisig wallet. Allow reject by user.
     from multisig import MultisigWallet
+    from miniscript import MiniScriptWallet
 
     UserAuthorizedAction.cleanup()
 
@@ -1457,9 +1456,12 @@ def maybe_enroll_xpub(sf_len=None, config=None, name=None, ux_reset=False, bsms_
 
     # this call will raise on parsing errors, so let them rise up
     # and be shown on screen/over usb
-    ms = MultisigWallet.from_file(config, name=name)
+    if miniscript:
+        msc = MiniScriptWallet.from_file(config, name=name)
+    else:
+        msc = MultisigWallet.from_file(config, name=name)
 
-    UserAuthorizedAction.active_request = NewEnrollRequest(ms, bsms_index=bsms_index)
+    UserAuthorizedAction.active_request = NewMiniscriptEnrollRequest(msc, bsms_index=bsms_index)
 
     if ux_reset:
         # for USB case, and import from PSBT