Added create_mnemonic_additional_share function,

fixed embedded index range

pybtc/functions/bip39_mnemonic.py

@@ -199,7 +199,8 @@ def split_mnemonic(mnemonic, threshold, total, language='english', embedded_inde
     entropy = mnemonic_to_entropy(mnemonic, language=language, hex=False,
                                   word_list_dir=word_list_dir, word_list=word_list)
     if embedded_index:
-        bits = math.ceil(math.log2(total)) + 1
+        bits = math.ceil(len(entropy) * 8 / 32)
+        # bits = math.ceil(math.log2(total)) + 1
     else:
         bits = 8
     shares = split_secret(threshold, total, entropy, bits)
@@ -215,6 +216,7 @@ def split_mnemonic(mnemonic, threshold, total, language='english', embedded_inde
             raise Exception("split secret failed")
     if embedded_index:
         result = []
+
         for share in shares:
             result.append(entropy_to_mnemonic(shares[share], language=language,
                                               word_list_dir=word_list_dir,
@@ -228,6 +230,43 @@ def split_mnemonic(mnemonic, threshold, total, language='english', embedded_inde
     return result
 
 
+def create_mnemonic_additional_share(threshold_shares, language='english', word_list_dir=None, word_list=None):
+    embedded_index = isinstance(threshold_shares, list)
+    s = dict()
+    if embedded_index:
+        for share in threshold_shares:
+            e = mnemonic_to_entropy(share, language=language, hex=False, word_list_dir=word_list_dir,
+                                           word_list=word_list)
+            i = get_mnemonic_checksum_data(share)
+            if i in s:
+                raise ValueError("Non unique or invalid shares")
+            s[i] = e
+    else:
+        for share in threshold_shares:
+            s[share] = mnemonic_to_entropy(threshold_shares[share], language=language,
+                                           hex=False, word_list_dir=word_list_dir, word_list=word_list)
+    if embedded_index:
+        bits =  math.ceil(len(s[next(iter(s))]) * 8 / 32)
+        index_max = 2 ** bits - 1
+        assert index_max > len(threshold_shares)
+    else:
+        index_max = 255
+
+    while True:
+        q = random.SystemRandom().randint(1, index_max)
+        if q in s:
+            continue
+        break
+    entropy = restore_secret(s, x = q)
+
+    if embedded_index:
+        return entropy_to_mnemonic(entropy, language=language, word_list_dir=word_list_dir,
+                                   data=q, word_list=word_list)
+    else:
+        return q, entropy_to_mnemonic(entropy, language=language, word_list_dir=word_list_dir, word_list=word_list)
+
+
+
 def combine_mnemonic(shares, language='english', word_list_dir=None, word_list=None):
     embedded_index = isinstance(shares, list)
     s = dict()

pybtc/functions/shamir.py

@@ -121,7 +121,7 @@ def split_secret(threshold, total,  secret, index_bits=8):
 
     return shares
 
-def restore_secret(shares):
+def restore_secret(shares, x=0):
     secret = b""
     share_length = None
     for share in shares:
@@ -134,5 +134,5 @@ def restore_secret(shares):
             raise Exception("Invalid shares")
 
     for i in range(share_length):
-        secret += bytes([_interpolation([(z, shares[z][i]) for z in  shares])])
+        secret += bytes([_interpolation([(z, shares[z][i]) for z in  shares], x=x)])
     return secret

setup.py

@@ -122,7 +122,7 @@ def run(self):
         return _build_ext.run(self)
 
 setup(name='pybtc',
-      version='2.3.8',
+      version='2.3.9',
       description='Python Bitcoin library',
       keywords='bitcoin',
       url='https://github.com/bitaps-com/pybtc',

tests/test_bip39_mnemonic_functions.py

@@ -8,6 +8,7 @@
 from pybtc.functions.bip39_mnemonic import is_mnemonic_checksum_valid
 from pybtc.functions.bip39_mnemonic import split_mnemonic
 from pybtc.functions.bip39_mnemonic import combine_mnemonic
+from pybtc.functions.bip39_mnemonic import create_mnemonic_additional_share
 
 def test_generate_entropy():
     assert len(generate_entropy()) == 64
@@ -135,4 +136,9 @@ def test_split_mnemonic():
               "wagon unique pilot subject cactus behave tide"]
 
     assert combine_mnemonic(shares) == "enforce north frost swear trial burst girl soccer rent town sea express other " \
-                                       "oblige insect youth swarm violin stable push twin close clump extra"
+                                       "oblige insect youth swarm violin stable push twin close clump extra"
+    shares = ["occur hazard mail question wisdom pill grass tackle fit nephew gown motion",
+              "embark fold seat fix quiz pull fortune wagon clever staff analyst symptom"]
+    s = create_mnemonic_additional_share(shares)
+
+    assert combine_mnemonic(shares) == combine_mnemonic([shares[0], s])