feat: scaffold security modules and TLS foundation

Data/Server/Modules/crypto/keys.py

@@ -0,0 +1,71 @@
+"""
+Utility helpers for working with Ed25519 keys and fingerprints.
+"""
+
+from __future__ import annotations
+
+import base64
+import hashlib
+import re
+from typing import Tuple
+
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.serialization import load_der_public_key
+from cryptography.hazmat.primitives.asymmetric import ed25519
+
+
+def generate_ed25519_keypair() -> Tuple[ed25519.Ed25519PrivateKey, bytes]:
+    """
+    Generate a new Ed25519 keypair.
+
+    Returns the private key object and the public key encoded as SubjectPublicKeyInfo DER bytes.
+    """
+
+    private_key = ed25519.Ed25519PrivateKey.generate()
+    public_key = private_key.public_key().public_bytes(
+        encoding=serialization.Encoding.DER,
+        format=serialization.PublicFormat.SubjectPublicKeyInfo,
+    )
+    return private_key, public_key
+
+
+def normalize_base64(data: str) -> str:
+    """
+    Collapse whitespace and normalise URL-safe encodings so we can reliably decode.
+    """
+
+    cleaned = re.sub(r"\\s+", "", data or "")
+    return cleaned.replace("-", "+").replace("_", "/")
+
+
+def spki_der_from_base64(spki_b64: str) -> bytes:
+    return base64.b64decode(normalize_base64(spki_b64), validate=True)
+
+
+def base64_from_spki_der(spki_der: bytes) -> str:
+    return base64.b64encode(spki_der).decode("ascii")
+
+
+def fingerprint_from_spki_der(spki_der: bytes) -> str:
+    digest = hashlib.sha256(spki_der).hexdigest()
+    return digest.lower()
+
+
+def fingerprint_from_base64_spki(spki_b64: str) -> str:
+    return fingerprint_from_spki_der(spki_der_from_base64(spki_b64))
+
+
+def private_key_to_pem(private_key: ed25519.Ed25519PrivateKey) -> bytes:
+    return private_key.private_bytes(
+        encoding=serialization.Encoding.PEM,
+        format=serialization.PrivateFormat.PKCS8,
+        encryption_algorithm=serialization.NoEncryption(),
+    )
+
+
+def public_key_to_pem(public_spki_der: bytes) -> bytes:
+    public_key = load_der_public_key(public_spki_der)
+    return public_key.public_bytes(
+        encoding=serialization.Encoding.PEM,
+        format=serialization.PublicFormat.SubjectPublicKeyInfo,
+    )