Actor class, and crypto for it, though we don't use them yet in this branch

django_kepi/crypto.py

@@ -0,0 +1,67 @@
+from Crypto.PublicKey import RSA
+from Crypto.Hash import SHA256
+from struct import pack
+import base64
+import hashlib
+
+def base64url_encode(data):
+    """
+    base64-encodes its input, using the modified URL-safe
+    alphabet given in RFC 4648.
+    """
+    b = base64.b64encode(s=data,
+            altchars=b'-_')
+    return str(b, encoding='ASCII')
+
+def bignum_to_bytes(bignum):
+
+    temp = bignum
+    result = []
+
+    while temp!=0:
+        result.append(temp & 0xFF)
+        temp >>= 8
+
+    result.reverse()
+    return bytes(result)
+
+class Key(object):
+    """
+    An RSA public/private key pair, which can produce
+    a magic-envelope signature for itself.
+
+    I was going to subclass the RSA key object,
+    but it's hidden away and has an underscore prefix,
+    so I guess the developers thought that was a bad idea.
+    So I'm wrapping it, instead.
+    """
+
+    def __init__(self):
+        self._rsa_key = RSA.generate(1024)
+
+    def private_as_pem(self):
+        return str(self._rsa_key.exportKey('PEM'),
+                encoding='ASCII')
+
+    def public_as_pem(self):
+        return str(self._rsa_key.publickey().exportKey('PEM'),
+                encoding='ASCII')
+
+    def modulus(self):
+        return self._rsa_key.n
+    
+    def public_exponent(self):
+        return self._rsa_key.e
+
+    def private_exponent(self):
+        return self._rsa_key.d
+
+    def magic_envelope(self):
+        return 'RSA.{0}.{1}'.format(
+                base64url_encode(
+                    bignum_to_bytes(
+                        self._rsa_key.n)),
+                base64url_encode(
+                    bignum_to_bytes(
+                        self._rsa_key.e)),
+                )

django_kepi/models/actor.py

@@ -0,0 +1,38 @@
+from django.db import models
+import django_kepi.models.thing
+import django_kepi.crypto
+import logging
+
+logger = logging.getLogger(name='django_kepi')
+
+######################
+
+class Actor(models.Model):
+
+    thing = models.OneToOneField(
+            'django_kepi.Thing',
+            primary_key=True,
+            on_delete=models.CASCADE,
+            )
+
+    privateKey = models.TextField(
+            )
+
+    publicKey = models.TextField(
+            )
+
+    @property
+    def name(self):
+        return self.thing.name
+
+    def save(self, *args, **kwargs):
+        if self.privateKey is None and self.publicKey is None:
+            logger.info('Generating key pair for %s.',
+                    self.name)
+            
+            key = django_kepi.crypto.Key()
+            self.privateKey = key.private_as_pem()
+            self.publicKey = key.public_as_pem()
+
+        super().save(*args, **kwargs)
+