feat: implement PBKDF2 algorithm with registry

pbkdf2_algorithm.py

@@ -0,0 +1,69 @@
+"""PBKDF2 algorithm implementation."""
+
+from __future__ import annotations
+
+import base64
+import binascii
+import hashlib
+import hmac
+import os
+
+DEFAULT_SALT_BYTES = 16
+DEFAULT_ITERATIONS = int(os.environ.get("PBKDF2_ITERATIONS", "200000"))
+
+
+class PBKDF2Algorithm:
+    """PBKDF2-HMAC-SHA256 password hashing algorithm."""
+
+    identifier = "pbkdf2"
+
+    def hash(
+        self,
+        password: str,
+        *,
+        iterations: int | None = None,
+        salt_bytes: int = DEFAULT_SALT_BYTES,
+    ) -> tuple[str, str]:
+        """Hash a password using PBKDF2-HMAC-SHA256."""
+        iterations = iterations or DEFAULT_ITERATIONS
+        salt = os.urandom(salt_bytes)
+        derived = hashlib.pbkdf2_hmac(
+            "sha256",
+            password.encode("utf-8"),
+            salt,
+            iterations,
+        )
+        return (
+            base64.b64encode(salt).decode("utf-8"),
+            base64.b64encode(derived).decode("utf-8"),
+        )
+
+    def verify(
+        self,
+        password: str,
+        salt_b64: str,
+        hash_b64: str,
+        *,
+        iterations: int | None = None,
+    ) -> bool:
+        """Verify a password against PBKDF2 salt and hash."""
+        iterations = iterations or DEFAULT_ITERATIONS
+        try:
+            salt = base64.b64decode(salt_b64, validate=True)
+            stored_hash = base64.b64decode(hash_b64, validate=True)
+        except (binascii.Error, ValueError):
+            return False
+
+        derived = hashlib.pbkdf2_hmac(
+            "sha256",
+            password.encode("utf-8"),
+            salt,
+            iterations,
+        )
+        return hmac.compare_digest(derived, stored_hash)
+
+
+from algorithms import register_algorithm
+
+# Auto-register when module is imported
+register_algorithm(PBKDF2Algorithm())