69 lines
2.0 KiB
Python
69 lines
2.0 KiB
Python
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import hashlib
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import struct
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from hmac import HMAC
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from spectre.scope import Scope, Scoper, default_scoper
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from spectre.template import Template, _characters, _templates
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class Spectre:
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def __init__(self, name: str, secret: str, scoper: Scoper = default_scoper):
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self._name = name
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self._secret = secret
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self._scoper = scoper
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self._key = self._user_key()
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def _user_key(self) -> bytes:
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name_bytes = self._name.encode()
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secret_bytes = self._secret.encode()
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key_scope = self._scoper.scope(Scope.AUTHENTICATION).encode()
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name_bytes_len = len(name_bytes)
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key_salt = key_scope + _big_endian(name_bytes_len) + name_bytes
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n = 32768 # N
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r = 8
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p = 2
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m = 128 * r * (n + p + 2)
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return hashlib.scrypt(
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secret_bytes, maxmem=m, salt=key_salt, n=n, r=r, p=p, dklen=64
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)
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def _site_key(self, name: str, counter: int, scope: Scope) -> bytes:
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name_bytes = name.encode()
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scope_bytes = self._scoper.scope(scope).encode()
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name_bytes_len = len(name_bytes)
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key_salt = (
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scope_bytes
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+ _big_endian(name_bytes_len)
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+ name_bytes
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+ _big_endian(counter)
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)
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return HMAC(self._key, msg=key_salt, digestmod=hashlib.sha256).digest()
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def site(
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self,
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site_name: str,
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template_type: Template = None,
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counter: int = 1,
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scope: Scope = Scope.AUTHENTICATION,
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) -> str:
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if not template_type:
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template_type = scope.default_template()
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site_key = self._site_key(site_name, counter, scope)
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template_set = _templates[template_type]
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template = template_set[site_key[0] % len(template_set)]
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out = ""
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for idx, b in enumerate(template):
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chars = _characters[b]
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char = chars[site_key[idx + 1] % len(chars)]
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out += char
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return out
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def _big_endian(n: int) -> bytes:
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return struct.pack(">I", n)
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