Merge branch 'tpatja-better-btc-addr-validation'

Author: kvesteri

tests/test_btc_address.py

@@ -4,17 +4,32 @@
 from validators import btc_address, ValidationFailure
 
 
-@pytest.mark.parametrize(('address',), [
-    ('17nuNm4QpgKuDvWy7Jh2AZ2nzZpMyKSKzT',),
-    ('3Cwgr2g7vsi1bXDUkpEnVoRLA9w4FZfC69',),
-])
-def test_returns_true_on_valid_mac_address(address):
-    assert btc_address(address)
+@pytest.mark.parametrize(
+    'value',
+    [
+        # P2PKH (Pay-to-PubkeyHash) type
+        '1BvBMSEYstWetqTFn5Au4m4GFg7xJaNVN2',
+        # P2SH (Pay to script hash) type
+        '3J98t1WpEZ73CNmQviecrnyiWrnqRhWNLy',
+        # Bech32/segwit type
+        'bc1qar0srrr7xfkvy5l643lydnw9re59gtzzwf5mdq',
+        'bc1qc7slrfxkknqcq2jevvvkdgvrt8080852dfjewde450xdlk4ugp7szw5tk9',
+    ],
+)
+def test_returns_true_on_valid_btc_address(value):
+    assert btc_address(value)
 
 
-@pytest.mark.parametrize(('address',), [
-    ('ff3Cwgr2g7vsi1bXDUkpEnVoRLA9w4FZfC69',),
-    ('b3Cgwgr2g7vsi1bXyjyDUkphEnVoRLA9w4FZfC69',),
-])
-def test_returns_failed_validation_on_invalid_mac_address(address):
-    assert isinstance(btc_address(address), ValidationFailure)
+@pytest.mark.parametrize(
+    'value',
+    [
+        'ff3Cwgr2g7vsi1bXDUkpEnVoRLA9w4FZfC69',
+        'b3Cgwgr2g7vsi1bXyjyDUkphEnVoRLA9w4FZfC69',
+        # incorrect header
+        '1BvBMsEYstWetqTFn5Au4m4GFg7xJaNVN2',
+        # incorrect checksum
+        '3J98t1WpEZ73CNmQviecrnyiWrnqRhWNLz',
+    ],
+)
+def test_returns_failed_validation_on_invalid_btc_address(value):
+    assert isinstance(btc_address(value), ValidationFailure)

validators/btc_address.py

@@ -1,8 +1,32 @@
 import re
+from hashlib import sha256
 
 from .utils import validator
 
-pattern = re.compile(r"^[13][a-km-zA-HJ-NP-Z1-9]{25,34}$")
+segwit_pattern = re.compile(
+    r'^(bc|tc)[0-3][02-9ac-hj-np-z]{14,74}$')
+
+
+def validate_segwit_address(addr):
+    return segwit_pattern.match(addr)
+
+
+def decode_base58(addr):
+    alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
+    return sum([
+        (58 ** e) * alphabet.index(i)
+        for e, i in enumerate(addr[::-1])
+    ])
+
+
+def validate_old_btc_address(addr):
+    "Validate P2PKH and P2SH type address"
+    if not len(addr) in range(25, 35):
+        return False
+    decoded_bytes = decode_base58(addr).to_bytes(25, "big")
+    header = decoded_bytes[:-4]
+    checksum = decoded_bytes[-4:]
+    return checksum == sha256(sha256(header).digest()).digest()[:4]
 
 
 @validator
@@ -13,11 +37,19 @@ def btc_address(value):
     If the value is valid bitcoin address this function returns ``True``,
     otherwise :class:`~validators.utils.ValidationFailure`.
 
+    Full validation is implemented for P2PKH and P2SH addresses.
+    For segwit addresses a regexp is used to provide a reasonable estimate
+    on whether the address is valid.
+
     Examples::
 
         >>> btc_address('3Cwgr2g7vsi1bXDUkpEnVoRLA9w4FZfC69')
         True
 
     :param value: Bitcoin address string to validate
     """
-    return pattern.match(value)
+    if not value or not isinstance(value, str):
+        return False
+    if value[:2] in ("bc", "tb"):
+        return validate_segwit_address(value)
+    return validate_old_btc_address(value)