feat: implement bcrypt algorithm

algorithms.py

@@ -43,3 +43,4 @@ def list_algorithms() -> list[str]:
 # Import to auto-register algorithms
 import pbkdf2_algorithm  # noqa: E402, F401
 import argon2_algorithm  # noqa: E402, F401
+import bcrypt_algorithm  # noqa: E402, F401

bcrypt_algorithm.py

@@ -0,0 +1,48 @@
+"""bcrypt algorithm implementation."""
+
+from __future__ import annotations
+
+import base64
+import binascii
+
+import bcrypt as bcrypt_lib
+
+
+class BcryptAlgorithm:
+    """bcrypt password hashing algorithm."""
+
+    identifier = "bcrypt"
+
+    def hash(self, password: str, **kwargs) -> tuple[str, str]:
+        """Hash a password using bcrypt.
+
+        Note: bcrypt generates its own salt internally and returns
+        a complete hash string that includes the salt.
+        We return empty string for salt_b64 and the full hash as hash_b64.
+        """
+        hashed = bcrypt_lib.hashpw(password.encode("utf-8"), bcrypt_lib.gensalt())
+        # Return empty salt since bcrypt embeds salt in hash
+        return ("", base64.b64encode(hashed).decode("utf-8"))
+
+    def verify(
+        self,
+        password: str,
+        salt_b64: str,
+        hash_b64: str,
+        **kwargs,
+    ) -> bool:
+        """Verify a password against bcrypt hash.
+
+        Note: salt_b64 is ignored since bcrypt embeds salt in the hash.
+        """
+        try:
+            hashed = base64.b64decode(hash_b64, validate=True)
+            return bcrypt_lib.checkpw(password.encode("utf-8"), hashed)
+        except (binascii.Error, ValueError):
+            return False
+
+
+from algorithms import register_algorithm
+
+# Auto-register when module is imported
+register_algorithm(BcryptAlgorithm())

tests/test_algorithms.py

@@ -52,3 +52,17 @@ def test_argon2_algorithm_identifier():
     """Verify Argon2 algorithm has correct identifier."""
     algo = get_algorithm("argon2")
     assert algo.identifier == "argon2"
+
+
+def test_bcrypt_algorithm_hash_round_trip():
+    """Verify bcrypt algorithm can hash and verify passwords."""
+    algo = get_algorithm("bcrypt")
+    salt, hashed = algo.hash("test password")
+    assert algo.verify("test password", salt, hashed)
+    assert not algo.verify("wrong password", salt, hashed)
+
+
+def test_bcrypt_algorithm_identifier():
+    """Verify bcrypt algorithm has correct identifier."""
+    algo = get_algorithm("bcrypt")
+    assert algo.identifier == "bcrypt"