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+#
+# Copyright (c) 2013 Pavol Rusnak
+# Copyright (c) 2017 mruddy
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy of
+# this software and associated documentation files (the "Software"), to deal in
+# the Software without restriction, including without limitation the rights to
+# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+# of the Software, and to permit persons to whom the Software is furnished to do
+# so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+#
+
+import bisect
+import hashlib
+import hmac
+import itertools
+import os
+from typing import AnyStr, List, Optional, Sequence, TypeVar, Union
+import unicodedata
+
+_T = TypeVar("_T")
+PBKDF2_ROUNDS = 2048
+
+
+class ConfigurationError(Exception):
+    pass
+
+
+# From <https://stackoverflow.com/questions/212358/binary-search-bisection-in-python/2233940#2233940>
+def binary_search(
+    a: Sequence[_T],
+    x: _T,
+    lo: int = 0,
+    hi: Optional[int] = None,  # can't use a to specify default for hi
+) -> int:
+    hi = hi if hi is not None else len(a)  # hi defaults to len(a)
+    pos = bisect.bisect_left(a, x, lo, hi)  # find insertion position
+    return pos if pos != hi and a[pos] == x else -1  # don't walk off the end
+
+
+# Refactored code segments from <https://github.com/keis/base58>
+def b58encode(v: bytes) -> str:
+    alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
+
+    p, acc = 1, 0
+    for c in reversed(v):
+        acc += p * c
+        p = p << 8
+
+    string = ""
+    while acc:
+        acc, idx = divmod(acc, 58)
+        string = alphabet[idx : idx + 1] + string
+    return string
+
+
+class Mnemonic(object):
+    def __init__(self, language: str):
+        self.language = language
+        self.radix = 2048
+        with open(
+            "%s/%s.txt" % (self._get_directory(), language), "r", encoding="utf-8"
+        ) as f:
+            self.wordlist = [w.strip() for w in f.readlines()]
+        if len(self.wordlist) != self.radix:
+            raise ConfigurationError(
+                "Wordlist should contain %d words, but it contains %d words."
+                % (self.radix, len(self.wordlist))
+            )
+
+    @staticmethod
+    def _get_directory() -> str:
+        return os.path.join(os.path.dirname(__file__), "wordlist")
+
+    @classmethod
+    def list_languages(cls) -> List[str]:
+        return [
+            f.split(".")[0]
+            for f in os.listdir(cls._get_directory())
+            if f.endswith(".txt")
+        ]
+
+    @staticmethod
+    def normalize_string(txt: AnyStr) -> str:
+        if isinstance(txt, bytes):
+            utxt = txt.decode("utf8")
+        elif isinstance(txt, str):
+            utxt = txt
+        else:
+            raise TypeError("String value expected")
+
+        return unicodedata.normalize("NFKD", utxt)
+
+    @classmethod
+    def detect_language(cls, code: str) -> str:
+        code = cls.normalize_string(code)
+        first = code.split(" ")[0]
+        languages = cls.list_languages()
+
+        for lang in languages:
+            mnemo = cls(lang)
+            if first in mnemo.wordlist:
+                return lang
+
+        raise ConfigurationError("Language not detected")
+
+    def generate(self, strength: int = 128) -> str:
+        if strength not in [128, 160, 192, 224, 256]:
+            raise ValueError(
+                "Strength should be one of the following [128, 160, 192, 224, 256], but it is not (%d)."
+                % strength
+            )
+        return self.to_mnemonic(os.urandom(strength // 8))
+
+    # Adapted from <http://tinyurl.com/oxmn476>
+    def to_entropy(self, words: Union[List[str], str]) -> bytearray:
+        if not isinstance(words, list):
+            words = words.split(" ")
+        if len(words) not in [12, 15, 18, 21, 24]:
+            raise ValueError(
+                "Number of words must be one of the following: [12, 15, 18, 21, 24], but it is not (%d)."
+                % len(words)
+            )
+        # Look up all the words in the list and construct the
+        # concatenation of the original entropy and the checksum.
+        concatLenBits = len(words) * 11
+        concatBits = [False] * concatLenBits
+        wordindex = 0
+        if self.language == "english":
+            use_binary_search = True
+        else:
+            use_binary_search = False
+        for word in words:
+            # Find the words index in the wordlist
+            ndx = (
+                binary_search(self.wordlist, word)
+                if use_binary_search
+                else self.wordlist.index(word)
+            )
+            if ndx < 0:
+                raise LookupError('Unable to find "%s" in word list.' % word)
+            # Set the next 11 bits to the value of the index.
+            for ii in range(11):
+                concatBits[(wordindex * 11) + ii] = (ndx & (1 << (10 - ii))) != 0
+            wordindex += 1
+        checksumLengthBits = concatLenBits // 33
+        entropyLengthBits = concatLenBits - checksumLengthBits
+        # Extract original entropy as bytes.
+        entropy = bytearray(entropyLengthBits // 8)
+        for ii in range(len(entropy)):
+            for jj in range(8):
+                if concatBits[(ii * 8) + jj]:
+                    entropy[ii] |= 1 << (7 - jj)
+        # Take the digest of the entropy.
+        hashBytes = hashlib.sha256(entropy).digest()
+        hashBits = list(
+            itertools.chain.from_iterable(
+                [c & (1 << (7 - i)) != 0 for i in range(8)] for c in hashBytes
+            )
+        )
+        # Check all the checksum bits.
+        for i in range(checksumLengthBits):
+            if concatBits[entropyLengthBits + i] != hashBits[i]:
+                raise ValueError("Failed checksum.")
+        return entropy
+
+    def to_mnemonic(self, data: bytes) -> str:
+        if len(data) not in [16, 20, 24, 28, 32]:
+            raise ValueError(
+                "Data length should be one of the following: [16, 20, 24, 28, 32], but it is not (%d)."
+                % len(data)
+            )
+        h = hashlib.sha256(data).hexdigest()
+        b = (
+            bin(int.from_bytes(data, byteorder="big"))[2:].zfill(len(data) * 8)
+            + bin(int(h, 16))[2:].zfill(256)[: len(data) * 8 // 32]
+        )
+        result = []
+        for i in range(len(b) // 11):
+            idx = int(b[i * 11 : (i + 1) * 11], 2)
+            result.append(self.wordlist[idx])
+        if self.language == "japanese":  # Japanese must be joined by ideographic space.
+            result_phrase = u"\u3000".join(result)
+        else:
+            result_phrase = " ".join(result)
+        return result_phrase
+
+    def check(self, mnemonic: str) -> bool:
+        mnemonic_list = self.normalize_string(mnemonic).split(" ")
+        # list of valid mnemonic lengths
+        if len(mnemonic_list) not in [12, 15, 18, 21, 24]:
+            return False
+        try:
+            idx = map(
+                lambda x: bin(self.wordlist.index(x))[2:].zfill(11), mnemonic_list
+            )
+            b = "".join(idx)
+        except ValueError:
+            return False
+        l = len(b)  # noqa: E741
+        d = b[: l // 33 * 32]
+        h = b[-l // 33 :]
+        nd = int(d, 2).to_bytes(l // 33 * 4, byteorder="big")
+        nh = bin(int(hashlib.sha256(nd).hexdigest(), 16))[2:].zfill(256)[: l // 33]
+        return h == nh
+
+    def expand_word(self, prefix: str) -> str:
+        if prefix in self.wordlist:
+            return prefix
+        else:
+            matches = [word for word in self.wordlist if word.startswith(prefix)]
+            if len(matches) == 1:  # matched exactly one word in the wordlist
+                return matches[0]
+            else:
+                # exact match not found.
+                # this is not a validation routine, just return the input
+                return prefix
+
+    def expand(self, mnemonic: str) -> str:
+        return " ".join(map(self.expand_word, mnemonic.split(" ")))
+
+    @classmethod
+    def to_seed(cls, mnemonic: str, passphrase: str = "") -> bytes:
+        mnemonic = cls.normalize_string(mnemonic)
+        passphrase = cls.normalize_string(passphrase)
+        passphrase = "mnemonic" + passphrase
+        mnemonic_bytes = mnemonic.encode("utf-8")
+        passphrase_bytes = passphrase.encode("utf-8")
+        stretched = hashlib.pbkdf2_hmac(
+            "sha512", mnemonic_bytes, passphrase_bytes, PBKDF2_ROUNDS
+        )
+        return stretched[:64]
+
+    @staticmethod
+    def to_hd_master_key(seed: bytes, testnet: bool = False) -> str:
+        if len(seed) != 64:
+            raise ValueError("Provided seed should have length of 64")
+
+        # Compute HMAC-SHA512 of seed
+        seed = hmac.new(b"Bitcoin seed", seed, digestmod=hashlib.sha512).digest()
+
+        # Serialization format can be found at: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#Serialization_format
+        xprv = b"\x04\x88\xad\xe4"  # Version for private mainnet
+        if testnet:
+            xprv = b"\x04\x35\x83\x94"  # Version for private testnet
+        xprv += b"\x00" * 9  # Depth, parent fingerprint, and child number
+        xprv += seed[32:]  # Chain code
+        xprv += b"\x00" + seed[:32]  # Master key
+
+        # Double hash using SHA256
+        hashed_xprv = hashlib.sha256(xprv).digest()
+        hashed_xprv = hashlib.sha256(hashed_xprv).digest()
+
+        # Append 4 bytes of checksum
+        xprv += hashed_xprv[:4]
+
+        # Return base58
+        return b58encode(xprv)
+
+
+def main() -> None:
+    import sys
+
+    if len(sys.argv) > 1:
+        hex_data = sys.argv[1]
+    else:
+        hex_data = sys.stdin.readline().strip()
+    data = bytes.fromhex(hex_data)
+    m = Mnemonic("english")
+    print(m.to_mnemonic(data))
+
+
+if __name__ == "__main__":
+    main()