fast hmac on python 3.7+

lib/bitcoin.py

@@ -31,7 +31,7 @@ from . import version
 from . import segwit_addr
 from . import constants
 from . import ecc
-from .crypto import Hash, sha256, hash_160
+from .crypto import Hash, sha256, hash_160, hmac_oneshot
 
 
 ################################## transactions
@@ -149,7 +149,7 @@ def add_number_to_script(i: int) -> bytes:
 
 hash_encode = lambda x: bh2u(x[::-1])
 hash_decode = lambda x: bfh(x)[::-1]
-hmac_sha_512 = lambda x, y: hmac.new(x, y, hashlib.sha512).digest()
+hmac_sha_512 = lambda x, y: hmac_oneshot(x, y, hashlib.sha512)
 
 
 def is_new_seed(x, prefix=version.SEED_PREFIX):
@@ -565,7 +565,7 @@ def _CKD_priv(k, c, s, is_prime):
         raise BitcoinException('Impossible xprv (not within curve order)') from e
     cK = keypair.get_public_key_bytes(compressed=True)
     data = bytes([0]) + k + s if is_prime else cK + s
-    I = hmac.new(c, data, hashlib.sha512).digest()
+    I = hmac_oneshot(c, data, hashlib.sha512)
     I_left = ecc.string_to_number(I[0:32])
     k_n = (I_left + ecc.string_to_number(k)) % ecc.CURVE_ORDER
     if I_left >= ecc.CURVE_ORDER or k_n == 0:
@@ -589,7 +589,7 @@ def CKD_pub(cK, c, n):
 # helper function, callable with arbitrary string.
 # note: 's' does not need to fit into 32 bits here! (c.f. trustedcoin billing)
 def _CKD_pub(cK, c, s):
-    I = hmac.new(c, cK + s, hashlib.sha512).digest()
+    I = hmac_oneshot(c, cK + s, hashlib.sha512)
     pubkey = ecc.ECPrivkey(I[0:32]) + ecc.ECPubkey(cK)
     if pubkey.is_at_infinity():
         raise ecc.InvalidECPointException()
@@ -683,7 +683,7 @@ def xpub_from_xprv(xprv):
 
 
 def bip32_root(seed, xtype):
-    I = hmac.new(b"Bitcoin seed", seed, hashlib.sha512).digest()
+    I = hmac_oneshot(b"Bitcoin seed", seed, hashlib.sha512)
     master_k = I[0:32]
     master_c = I[32:]
     # create xprv first, as that will check if master_k is within curve order

lib/crypto.py

@@ -26,6 +26,7 @@
 import base64
 import os
 import hashlib
+import hmac
 
 import pyaes
 
@@ -140,3 +141,11 @@ def hash_160(x: bytes) -> bytes:
         from . import ripemd
         md = ripemd.new(sha256(x))
         return md.digest()
+
+
+def hmac_oneshot(key: bytes, msg: bytes, digest) -> bytes:
+    if hasattr(hmac, 'digest'):
+        # requires python 3.7+; faster
+        return hmac.digest(key, msg, digest)
+    else:
+        return hmac.new(key, msg, digest).digest()

lib/ecc.py

@@ -36,7 +36,7 @@ from ecdsa.ellipticcurve import Point
 from ecdsa.util import string_to_number, number_to_string
 
 from .util import bfh, bh2u, assert_bytes, print_error, to_bytes, InvalidPassword, profiler
-from .crypto import (Hash, aes_encrypt_with_iv, aes_decrypt_with_iv)
+from .crypto import (Hash, aes_encrypt_with_iv, aes_decrypt_with_iv, hmac_oneshot)
 from .ecc_fast import do_monkey_patching_of_python_ecdsa_internals_with_libsecp256k1
 
 
@@ -285,7 +285,7 @@ class ECPubkey(object):
         ciphertext = aes_encrypt_with_iv(key_e, iv, message)
         ephemeral_pubkey = ephemeral.get_public_key_bytes(compressed=True)
         encrypted = magic + ephemeral_pubkey + ciphertext
-        mac = hmac.new(key_m, encrypted, hashlib.sha256).digest()
+        mac = hmac_oneshot(key_m, encrypted, hashlib.sha256)
 
         return base64.b64encode(encrypted + mac)
 
@@ -424,7 +424,7 @@ class ECPrivkey(ECPubkey):
         ecdh_key = (ephemeral_pubkey * self.secret_scalar).get_public_key_bytes(compressed=True)
         key = hashlib.sha512(ecdh_key).digest()
         iv, key_e, key_m = key[0:16], key[16:32], key[32:]
-        if mac != hmac.new(key_m, encrypted[:-32], hashlib.sha256).digest():
+        if mac != hmac_oneshot(key_m, encrypted[:-32], hashlib.sha256):
             raise InvalidPassword()
         return aes_decrypt_with_iv(key_e, iv, ciphertext)