core: modify function signatures to match python-shamir-mnemonic

core/src/apps/common/mnemonic.py

@@ -48,7 +48,7 @@ def get_seed(passphrase: str = "", progress_bar: bool = True) -> bytes:
             # Identifier or exponent expected but not found
             raise RuntimeError
         seed = slip39.decrypt(
-            identifier, iteration_exponent, mnemonic_secret, passphrase.encode()
+            mnemonic_secret, passphrase.encode(), iteration_exponent, identifier
         )
 
     return seed

core/src/apps/debug/load_device.py

@@ -24,15 +24,17 @@ async def load_device(ctx, msg):
         secret = msg.mnemonics[0].encode()
         backup_type = BackupType.Bip39
     else:
-        identifier, iteration_exponent, secret, group_count = slip39.combine_mnemonics(
-            msg.mnemonics
-        )
-        if group_count == 1:
+        identifier, iteration_exponent, secret = slip39.recover_ems(msg.mnemonics)
+
+        # this must succeed if the recover_ems call succeeded
+        share = slip39.decode_mnemonic(msg.mnemonics[0])
+        if share.group_count == 1:
             backup_type = BackupType.Slip39_Basic
-        elif group_count > 1:
+        elif share.group_count > 1:
             backup_type = BackupType.Slip39_Advanced
         else:
             raise RuntimeError("Invalid group count")
+
         storage.device.set_slip39_identifier(identifier)
         storage.device.set_slip39_iteration_exponent(iteration_exponent)
 

core/src/apps/management/recovery_device/recover.py

@@ -46,9 +46,7 @@ def process_slip39(words: str) -> Tuple[Optional[bytes], slip39.Share]:
         # if share threshold and group threshold are 1
         # we can calculate the secret right away
         if share.threshold == 1 and share.group_threshold == 1:
-            identifier, iteration_exponent, secret, _ = slip39.combine_mnemonics(
-                [words]
-            )
+            identifier, iteration_exponent, secret = slip39.recover_ems([words])
             return secret, share
         else:
             # we need more shares
@@ -89,7 +87,7 @@ def process_slip39(words: str) -> Tuple[Optional[bytes], slip39.Share]:
         # in case of slip39 basic we only need the first and only group
         mnemonics = storage.recovery_shares.fetch_group(0)
 
-    identifier, iteration_exponent, secret, _ = slip39.combine_mnemonics(mnemonics)
+    identifier, iteration_exponent, secret = slip39.recover_ems(mnemonics)
     return secret, share
 
 

core/src/apps/management/reset_device/__init__.py

@@ -101,12 +101,12 @@ async def backup_slip39_basic(
     threshold = await layout.slip39_prompt_threshold(ctx, shares_count)
 
     # generate the mnemonics
-    mnemonics = slip39.generate_mnemonics_from_data(
-        encrypted_master_secret,
-        storage.device.get_slip39_identifier(),
+    mnemonics = slip39.split_ems(
         1,  # Single Group threshold
         [(threshold, shares_count)],  # Single Group threshold/count
+        storage.device.get_slip39_identifier(),
         storage.device.get_slip39_iteration_exponent(),
+        encrypted_master_secret,
     )[0]
 
     # show and confirm individual shares
@@ -136,12 +136,12 @@ async def backup_slip39_advanced(
         groups.append((share_threshold, share_count))
 
     # generate the mnemonics
-    mnemonics = slip39.generate_mnemonics_from_data(
-        encrypted_master_secret=encrypted_master_secret,
-        identifier=storage.device.get_slip39_identifier(),
+    mnemonics = slip39.split_ems(
         group_threshold=group_threshold,
         groups=groups,
+        identifier=storage.device.get_slip39_identifier(),
         iteration_exponent=storage.device.get_slip39_iteration_exponent(),
+        encrypted_master_secret=encrypted_master_secret,
     )
 
     # show and confirm individual shares

core/src/trezor/crypto/slip39.py

@@ -165,10 +165,10 @@ class Share:
 
 
 def decrypt(
-    identifier: int,
-    iteration_exponent: int,
     encrypted_master_secret: bytes,
     passphrase: bytes,
+    iteration_exponent: int,
+    identifier: int,
 ) -> bytes:
     """
     Converts the Encrypted Master Secret to a Master Secret by applying the passphrase.
@@ -194,12 +194,12 @@ def generate_random_identifier() -> int:
     return identifier & ((1 << _ID_LENGTH_BITS) - 1)
 
 
-def generate_mnemonics_from_data(
-    encrypted_master_secret: bytes,  # The encrypted master secret to split.
-    identifier: int,
+def split_ems(
     group_threshold: int,  # The number of groups required to reconstruct the master secret.
     groups: List[Tuple[int, int]],  # A list of (member_threshold, member_count).
+    identifier: int,
     iteration_exponent: int,
+    encrypted_master_secret: bytes,  # The encrypted master secret to split.
 ) -> List[List[str]]:
     """
     Splits an encrypted master secret into mnemonic shares using Shamir's secret sharing scheme.
@@ -253,7 +253,7 @@ def generate_mnemonics_from_data(
     return mnemonics
 
 
-def combine_mnemonics(mnemonics: List[str]) -> Tuple[int, int, bytes, int]:
+def recover_ems(mnemonics: List[str]) -> Tuple[int, int, bytes]:
     """
     Combines mnemonic shares to obtain the encrypted master secret which was previously
     split using Shamir's secret sharing scheme.
@@ -292,7 +292,7 @@ def combine_mnemonics(mnemonics: List[str]) -> Tuple[int, int, bytes, int]:
     ]
 
     encrypted_master_secret = _recover_secret(group_threshold, group_shares)
-    return identifier, iteration_exponent, encrypted_master_secret, group_count
+    return identifier, iteration_exponent, encrypted_master_secret
 
 
 def decode_mnemonic(mnemonic: str) -> Share: