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import base64
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from ecdsa import SigningKey, VerifyingKey, BadSignatureError
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from django.db import models
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TYPE_ECDSA = 'ecdsa'
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APP_LABEL_BOARDS = 'boards'
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class KeyPairManager(models.Manager):
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def generate_key(self, key_type=TYPE_ECDSA, primary=False):
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if primary and self.filter(primary=True).exists():
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raise Exception('There can be only one primary key')
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if key_type == TYPE_ECDSA:
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private = SigningKey.generate()
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public = private.get_verifying_key()
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private_key_str = base64.b64encode(private.to_string()).decode()
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public_key_str = base64.b64encode(public.to_string()).decode()
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return self.create(public_key=public_key_str,
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private_key=private_key_str,
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key_type=TYPE_ECDSA, primary=primary)
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else:
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raise Exception('Key type not supported')
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def verify(self, signature, string):
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if signature.key_type == TYPE_ECDSA:
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public = VerifyingKey.from_string(base64.b64decode(signature.key))
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signature_byte = base64.b64decode(signature.signature)
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try:
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return public.verify(signature_byte, string.encode())
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except BadSignatureError:
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return False
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else:
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raise Exception('Key type not supported')
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def has_primary(self):
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return self.filter(primary=True).exists()
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class KeyPair(models.Model):
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class Meta:
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app_label = APP_LABEL_BOARDS
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objects = KeyPairManager()
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public_key = models.TextField()
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private_key = models.TextField()
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key_type = models.TextField()
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primary = models.BooleanField(default=False)
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def __str__(self):
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return '%s::%s' % (self.key_type, self.public_key)
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def sign(self, string):
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private = SigningKey.from_string(base64.b64decode(
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self.private_key.encode()))
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signature_byte = private.sign_deterministic(string.encode())
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return base64.b64encode(signature_byte).decode()
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