kopia lustrzana https://github.com/markqvist/reticulum
115 wiersze
4.4 KiB
Python
115 wiersze
4.4 KiB
Python
# Reticulum License
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#
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# Copyright (c) 2016-2025 Mark Qvist
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# - The Software shall not be used in any kind of system which includes amongst
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# its functions the ability to purposefully do harm to human beings.
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#
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# - The Software shall not be used, directly or indirectly, in the creation of
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# an artificial intelligence, machine learning or language model training
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# dataset, including but not limited to any use that contributes to the
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# training or development of such a model or algorithm.
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#
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# - The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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import os
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import time
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from RNS.Cryptography import HMAC
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from RNS.Cryptography import PKCS7
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from RNS.Cryptography import AES
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from RNS.Cryptography.AES import AES_128_CBC
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from RNS.Cryptography.AES import AES_256_CBC
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class Token():
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"""
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This class provides a slightly modified implementation of the Fernet spec
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found at: https://github.com/fernet/spec/blob/master/Spec.md
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According to the spec, a Fernet token includes a one byte VERSION and
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eight byte TIMESTAMP field at the start of each token. These fields are
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not relevant to Reticulum. They are therefore stripped from this
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implementation, since they incur overhead and leak initiator metadata.
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"""
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TOKEN_OVERHEAD = 48 # Bytes
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@staticmethod
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def generate_key(mode=AES_256_CBC):
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if mode == AES_128_CBC: return os.urandom(32)
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elif mode == AES_256_CBC: return os.urandom(64)
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else: raise TypeError(f"Invalid token mode: {mode}")
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def __init__(self, key=None, mode=AES):
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if key == None: raise ValueError("Token key cannot be None")
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if mode == AES:
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if len(key) == 32:
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self.mode = AES_128_CBC
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self._signing_key = key[:16]
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self._encryption_key = key[16:]
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elif len(key) == 64:
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self.mode = AES_256_CBC
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self._signing_key = key[:32]
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self._encryption_key = key[32:]
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else: raise ValueError("Token key must be 128 or 256 bits, not "+str(len(key)*8))
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else: raise TypeError(f"Invalid token mode: {mode}")
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def verify_hmac(self, token):
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if len(token) <= 32: raise ValueError("Cannot verify HMAC on token of only "+str(len(token))+" bytes")
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else:
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received_hmac = token[-32:]
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expected_hmac = HMAC.new(self._signing_key, token[:-32]).digest()
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if received_hmac == expected_hmac: return True
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else: return False
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def encrypt(self, data = None):
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if not isinstance(data, bytes): raise TypeError("Token plaintext input must be bytes")
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iv = os.urandom(16)
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ciphertext = self.mode.encrypt(
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plaintext = PKCS7.pad(data),
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key = self._encryption_key,
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iv = iv)
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signed_parts = iv+ciphertext
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return signed_parts + HMAC.new(self._signing_key, signed_parts).digest()
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def decrypt(self, token = None):
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if not isinstance(token, bytes): raise TypeError("Token must be bytes")
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if not self.verify_hmac(token): raise ValueError("Token HMAC was invalid")
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iv = token[:16]
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ciphertext = token[16:-32]
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try:
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return PKCS7.unpad(
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self.mode.decrypt(
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ciphertext = ciphertext,
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key = self._encryption_key,
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iv = iv))
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except Exception as e: raise ValueError(f"Could not decrypt token: {e}")
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