support BIP-0039

pybtc/constants.py

@@ -1,6 +1,7 @@
 from secp256k1 import lib as secp256k1
 from secp256k1 import ffi
 import random
+import os
 
 SIGHASH_ALL           = 0x00000001
 SIGHASH_NONE          = 0x00000002
@@ -74,3 +75,5 @@ SCRIPT_TYPES = { "P2PKH":        0,
                  "NON_STANDART": 7
                 }
 
+ROOT_DIR = os.path.abspath(os.path.dirname(__file__))
+BIP0039_DIR = os.path.normpath(os.path.join(ROOT_DIR, 'bip-0039'))

pybtc/tools.py

@@ -700,3 +700,74 @@ def i2b(i): return bn2vch(i)
 
 def b2i(b): return vch2bn(b)
 
+
+
+
+
+
+# BIP39
+#
+#
+#
+
+def create_mnemonic(bits=256, language='english'):
+    passphrase = []
+    wordlist = create_wordlist(language)
+    entropy = os.urandom(bits // 8)
+    entropy_int = int.from_bytes(entropy, byteorder="big")
+    entropy_bit_len = len(entropy) * 8
+    chk_sum_bit_len = entropy_bit_len // 32
+    entropy_hash = hashlib.sha256(entropy).hexdigest()
+    fbyte_hash = unhexlify(entropy_hash)[0]
+    entropy_int = add_checksum(entropy)
+    while entropy_int:
+        passphrase.append(wordlist[entropy_int & 0b11111111111])
+        entropy_int = entropy_int >> 11
+    return ' '.join(passphrase[::-1])
+
+
+def create_wordlist(language, wordlist_dir=BIP0039_DIR):
+    f = None
+    path = os.path.join(wordlist_dir, '.'.join((language, 'txt')))
+    assert os.path.exists(path)
+    f = open(path)
+    content = f.read().rstrip('\n')
+    assert content
+    f.close()
+    return content.split('\n')
+
+
+def add_checksum(data):
+    mask = 0b10000000
+    data_int = int.from_bytes(data, byteorder="big")
+    data_bit_len = len(data) * 8 // 32
+    data_hash = hashlib.sha256(data).hexdigest()
+    fbyte_hash = unhexlify(data_hash)[0]
+    while data_bit_len:
+        data_bit_len -= 1
+        data_int = (data_int << 1) | 1 if fbyte_hash & mask else data_int << 1
+        mask = mask >> 1
+    return data_int
+
+
+def mnemonic2bytes(mnemonic, language):
+    wordlist = create_wordlist(language)
+    codes = dict()
+    for code, word in enumerate(wordlist):
+        codes[word] = code
+    word_count = len(mnemonic)
+    entropy_int = None
+    bit_size = word_count * 11
+    chk_sum_bit_len = word_count * 11 % 32
+    for word in mnemonic:
+        entropy_int = (entropy_int << 11) | codes[word] if entropy_int else codes[word]
+
+    chk_sum = entropy_int & (2 ** chk_sum_bit_len - 1)
+    entropy_int = entropy_int >> chk_sum_bit_len
+    entropy = entropy_int.to_bytes((bit_size - chk_sum_bit_len) // 8, byteorder="big")
+    ent_hash = hashlib.sha256(entropy).hexdigest()
+    fb = unhexlify(ent_hash)[0]
+    assert (fb >> (8 - chk_sum_bit_len)) & chk_sum
+    return entropy
+
+