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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 = private.to_pem().decode()
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public_key_str = public.to_pem().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, public_key_str, string, signature, key_type=TYPE_ECDSA):
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if key_type == TYPE_ECDSA:
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public = VerifyingKey.from_pem(public_key_str)
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signature_byte = base64.b64decode(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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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_pem(self.private_key)
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signature_byte = private.sign(string.encode())
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return base64.b64encode(signature_byte)
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