Made all bip32 primitives testnet compatible.

11 years ago · 0ac02bf040
2 changed files with 80 additions and 22 deletions
--- a/lib/bitcoin.py
+++ b/lib/bitcoin.py
@ -640,23 +640,54 @@ def _CKD_pub(cK, c, s):
    return cK_n, c_n


+BITCOIN_HEADERS = ["0488ade4", "0488b21e"]
+TESTNET_HEADERS = ["043587cf", "04358394"]
+
+BITCOIN_HEAD = "0488ade4"
+TESTNET_HEAD = "04358394"
+
+BITCOIN_HEADER_PRIV = "0488ADE4"
+BITCOIN_HEADER_PUB = "0488B21E"
+
+TESTNET_HEADER_PRIV = "04358394"
+TESTNET_HEADER_PUB = "043587CF"
+
+
+def _get_headers(testnet):
+    """Returns the correct headers for either testnet or bitcoin, in the form
+    of a 2-tuple, like (public, private)."""
+    if testnet:
+        return (TESTNET_HEADER_PUB, TESTNET_HEADER_PRIV)
+    else:
+        return (BITCOIN_HEADER_PUB, BITCOIN_HEADER_PRIV)
+

 def deserialize_xkey(xkey):
+
    xkey = DecodeBase58Check(xkey)
    assert len(xkey) == 78
-    assert xkey[0:4].encode('hex') in ["0488ade4", "0488b21e"]
+
+    xkey_header = xkey[0:4].encode('hex')
+    # Determine if the key is a bitcoin key or a testnet key.
+    if xkey_header in TESTNET_HEADERS:
+        head = TESTNET_HEAD
+    elif xkey_header in BITCOIN_HEADERS:
+        head = BITCOIN_HEAD
+    else:
+        raise Exception("Unknown xkey header: '%s'" % xkey_header)
+
    depth = ord(xkey[4])
    fingerprint = xkey[5:9]
    child_number = xkey[9:13]
    c = xkey[13:13+32]
-    if xkey[0:4].encode('hex') == "0488ade4":
+    if xkey[0:4].encode('hex') == head:
        K_or_k = xkey[13+33:]
    else:
        K_or_k = xkey[13+32:]
    return depth, fingerprint, child_number, c, K_or_k


-def get_xkey_name(xkey):
+def get_xkey_name(xkey, testnet=False):
    depth, fingerprint, child_number, c, K = deserialize_xkey(xkey)
    n = int(child_number.encode('hex'), 16)
    if n & BIP32_PRIME:
@ -671,27 +702,29 @@ def get_xkey_name(xkey):
        raise BaseException("xpub depth error")


-def xpub_from_xprv(xprv):
+def xpub_from_xprv(xprv, testnet=False):
    depth, fingerprint, child_number, c, k = deserialize_xkey(xprv)
    K, cK = get_pubkeys_from_secret(k)
-    xpub = "0488B21E".decode('hex') + chr(depth) + fingerprint + child_number + c + cK
+    header_pub, _  = _get_headers(testnet)
+    xpub = header_pub.decode('hex') + chr(depth) + fingerprint + child_number + c + cK
    return EncodeBase58Check(xpub)


-def bip32_root(seed):
+def bip32_root(seed, testnet=False):
    import hmac
+    header_pub, header_priv = _get_headers(testnet)
    seed = seed.decode('hex')
    I = hmac.new("Bitcoin seed", seed, hashlib.sha512).digest()
    master_k = I[0:32]
    master_c = I[32:]
    K, cK = get_pubkeys_from_secret(master_k)
-    xprv = ("0488ADE4" + "00" + "00000000" + "00000000").decode("hex") + master_c + chr(0) + master_k
-    xpub = ("0488B21E" + "00" + "00000000" + "00000000").decode("hex") + master_c + cK
+    xprv = (header_priv + "00" + "00000000" + "00000000").decode("hex") + master_c + chr(0) + master_k
+    xpub = (header_pub + "00" + "00000000" + "00000000").decode("hex") + master_c + cK
    return EncodeBase58Check(xprv), EncodeBase58Check(xpub)


-
-def bip32_private_derivation(xprv, branch, sequence):
+def bip32_private_derivation(xprv, branch, sequence, testnet=False):
+    header_pub, header_priv = _get_headers(testnet)
    depth, fingerprint, child_number, c, k = deserialize_xkey(xprv)
    assert sequence.startswith(branch)
    sequence = sequence[len(branch):]
@ -706,13 +739,13 @@ def bip32_private_derivation(xprv, branch, sequence):
    fingerprint = hash_160(parent_cK)[0:4]
    child_number = ("%08X"%i).decode('hex')
    K, cK = get_pubkeys_from_secret(k)
-    xprv = "0488ADE4".decode('hex') + chr(depth) + fingerprint + child_number + c + chr(0) + k
-    xpub = "0488B21E".decode('hex') + chr(depth) + fingerprint + child_number + c + cK
+    xprv = header_priv.decode('hex') + chr(depth) + fingerprint + child_number + c + chr(0) + k
+    xpub = header_pub.decode('hex') + chr(depth) + fingerprint + child_number + c + cK
    return EncodeBase58Check(xprv), EncodeBase58Check(xpub)


-
-def bip32_public_derivation(xpub, branch, sequence):
+def bip32_public_derivation(xpub, branch, sequence, testnet=False):
+    header_pub, _ = _get_headers(testnet)
    depth, fingerprint, child_number, c, cK = deserialize_xkey(xpub)
    assert sequence.startswith(branch)
    sequence = sequence[len(branch):]
@ -725,7 +758,7 @@ def bip32_public_derivation(xpub, branch, sequence):

    fingerprint = hash_160(parent_cK)[0:4]
    child_number = ("%08X"%i).decode('hex')
-    xpub = "0488B21E".decode('hex') + chr(depth) + fingerprint + child_number + c + cK
+    xpub = header_pub.decode('hex') + chr(depth) + fingerprint + child_number + c + cK
    return EncodeBase58Check(xpub)


--- a/lib/tests/test_bitcoin.py
+++ b/lib/tests/test_bitcoin.py
@ -6,7 +6,7 @@ from lib.bitcoin import (
    generator_secp256k1, point_to_ser, public_key_to_bc_address, EC_KEY,
    bip32_root, bip32_public_derivation, bip32_private_derivation, pw_encode,
    pw_decode, Hash, public_key_from_private_key, address_from_private_key,
-    is_valid, is_private_key, mnemonic_to_seed)
+    is_valid, is_private_key, mnemonic_to_seed, xpub_from_xprv)

 try:
    import ecdsa
@ -49,24 +49,33 @@ class Test_bitcoin(unittest.TestCase):

    def test_bip32(self):
        # see https://en.bitcoin.it/wiki/BIP_0032_TestVectors
-        xpub, xprv = self._do_test_bip32("000102030405060708090a0b0c0d0e0f", "m/0'/1/2'/2/1000000000")
+        xpub, xprv = self._do_test_bip32("000102030405060708090a0b0c0d0e0f", "m/0'/1/2'/2/1000000000", testnet=False)
        assert xpub == "xpub6H1LXWLaKsWFhvm6RVpEL9P4KfRZSW7abD2ttkWP3SSQvnyA8FSVqNTEcYFgJS2UaFcxupHiYkro49S8yGasTvXEYBVPamhGW6cFJodrTHy"
        assert xprv == "xprvA41z7zogVVwxVSgdKUHDy1SKmdb533PjDz7J6N6mV6uS3ze1ai8FHa8kmHScGpWmj4WggLyQjgPie1rFSruoUihUZREPSL39UNdE3BBDu76"

-        xpub, xprv = self._do_test_bip32("fffcf9f6f3f0edeae7e4e1dedbd8d5d2cfccc9c6c3c0bdbab7b4b1aeaba8a5a29f9c999693908d8a8784817e7b7875726f6c696663605d5a5754514e4b484542","m/0/2147483647'/1/2147483646'/2")
+        xpub, xprv = self._do_test_bip32("fffcf9f6f3f0edeae7e4e1dedbd8d5d2cfccc9c6c3c0bdbab7b4b1aeaba8a5a29f9c999693908d8a8784817e7b7875726f6c696663605d5a5754514e4b484542","m/0/2147483647'/1/2147483646'/2", testnet=False)
        assert xpub == "xpub6FnCn6nSzZAw5Tw7cgR9bi15UV96gLZhjDstkXXxvCLsUXBGXPdSnLFbdpq8p9HmGsApME5hQTZ3emM2rnY5agb9rXpVGyy3bdW6EEgAtqt"
        assert xprv == "xprvA2nrNbFZABcdryreWet9Ea4LvTJcGsqrMzxHx98MMrotbir7yrKCEXw7nadnHM8Dq38EGfSh6dqA9QWTyefMLEcBYJUuekgW4BYPJcr9E7j"

-    def _do_test_bip32(self, seed, sequence):
-        xprv, xpub = bip32_root(seed)
+    def test_bip32_testnet(self):
+        xpub, xprv = self._do_test_bip32("000102030405060708090a0b0c0d0e0f", "m/0'/1/2'/2/1000000000", testnet=True)
+        assert xpub == "tpubDHNy3kAG39ThyiwwsgoKY4iRenXDRtce8qdCFJZXPMCJg5dsCUHayp84raLTpvyiNA9sXPob5rgqkKvkN8S7MMyXbnEhGJMW64Cf4vFAoaF"
+        assert xprv == "tprv8kgvuL81tmn36Fv9z38j8f4K5m1HGZRjZY2QxnXDy5PuqbP6a5TzoKWCgTcGHBu66W3TgSbAu2yX6sPza5FkHmy564Sh6gmCPUNeUt4yj2x"
+
+        xpub, xprv = self._do_test_bip32("fffcf9f6f3f0edeae7e4e1dedbd8d5d2cfccc9c6c3c0bdbab7b4b1aeaba8a5a29f9c999693908d8a8784817e7b7875726f6c696663605d5a5754514e4b484542","m/0/2147483647'/1/2147483646'/2", testnet=True)
+        assert xpub == "tpubDG9qJLc8hq8PMG7y4sQEodLSocEkfj4mGrUC75b7G76mDoqybcUXvmvRsruvLeF14mhixobZwZP6LwqeFePKU83Sv8ZnxWdHBb6VzE6zbvC"
+        assert xprv == "tprv8jTo9vZtZTSiTo6BBDjeQDgLEaipWPsrhYsQpZYoqqJNPKbCyDewkHJZhkoSHiWYCUf1Gm4TFzQxcG4D6s1J9Hsn4whDK7QYyHHokJeUuac"
+
+    def _do_test_bip32(self, seed, sequence, testnet):
+        xprv, xpub = bip32_root(seed, testnet)
        assert sequence[0:2] == "m/"
        path = 'm'
        sequence = sequence[2:]
        for n in sequence.split('/'):
            child_path = path + '/' + n
            if n[-1] != "'":
-                xpub2 = bip32_public_derivation(xpub, path, child_path)
-            xprv, xpub = bip32_private_derivation(xprv, path, child_path)
+                xpub2 = bip32_public_derivation(xpub, path, child_path, testnet)
+            xprv, xpub = bip32_private_derivation(xprv, path, child_path, testnet)
            if n[-1] != "'":
                assert xpub == xpub2
            path = child_path
@ -109,6 +118,22 @@ class Test_bitcoin(unittest.TestCase):
        result = Hash(payload)
        self.assertEqual(expected, result)

+    def test_xpub_from_xprv(self):
+        """We can derive the xpub key from a xprv."""
+        # Taken from test vectors in https://en.bitcoin.it/wiki/BIP_0032_TestVectors
+        xpub = "xpub6H1LXWLaKsWFhvm6RVpEL9P4KfRZSW7abD2ttkWP3SSQvnyA8FSVqNTEcYFgJS2UaFcxupHiYkro49S8yGasTvXEYBVPamhGW6cFJodrTHy"
+        xprv = "xprvA41z7zogVVwxVSgdKUHDy1SKmdb533PjDz7J6N6mV6uS3ze1ai8FHa8kmHScGpWmj4WggLyQjgPie1rFSruoUihUZREPSL39UNdE3BBDu76"
+
+        result = xpub_from_xprv(xprv)
+        self.assertEqual(result, xpub)
+
+    def test_xpub_from_xprv_testnet(self):
+        """We can derive the xpub key from a xprv using testnet headers."""
+        xpub = "tpubDHNy3kAG39ThyiwwsgoKY4iRenXDRtce8qdCFJZXPMCJg5dsCUHayp84raLTpvyiNA9sXPob5rgqkKvkN8S7MMyXbnEhGJMW64Cf4vFAoaF"
+        xprv = "tprv8kgvuL81tmn36Fv9z38j8f4K5m1HGZRjZY2QxnXDy5PuqbP6a5TzoKWCgTcGHBu66W3TgSbAu2yX6sPza5FkHmy564Sh6gmCPUNeUt4yj2x"
+        result = xpub_from_xprv(xprv, testnet=True)
+        self.assertEqual(result, xpub)
+

 class Test_keyImport(unittest.TestCase):
    """ The keys used in this class are TEST keys from