483 lines
18 KiB
Python
483 lines
18 KiB
Python
import base64
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import math
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import os
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import RNS
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import time
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import atexit
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import base64
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from .vendor import umsgpack as umsgpack
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives import hashes
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from cryptography.hazmat.primitives import serialization
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from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey, Ed25519PublicKey
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from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey, X25519PublicKey
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from cryptography.hazmat.primitives.kdf.hkdf import HKDF
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from cryptography.fernet import Fernet
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class Identity:
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"""
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This class is used to manage identities in Reticulum. It provides methods
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for encryption, decryption, signatures and verification, and is the basis
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for all encrypted communication over Reticulum networks.
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:param create_keys: Specifies whether new encryption and signing keys should be generated.
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"""
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CURVE = "Curve25519"
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"""
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The curve used for Elliptic Curve DH key exchanges
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"""
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KEYSIZE = 256*2
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"""
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X25519 key size in bits. A complete key is the concatenation of a 256 bit encryption key, and a 256 bit signing key.
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"""
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# Non-configurable constants
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FERNET_VERSION = 0x80
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FERNET_OVERHEAD = 54 # In bytes
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AES128_BLOCKSIZE = 16 # In bytes
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HASHLENGTH = 256 # In bits
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SIGLENGTH = KEYSIZE # In bits
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TRUNCATED_HASHLENGTH = RNS.Reticulum.TRUNCATED_HASHLENGTH
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"""
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Constant specifying the truncated hash length (in bits) used by Reticulum
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for addressable hashes and other purposes. Non-configurable.
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"""
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# Storage
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known_destinations = {}
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@staticmethod
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def remember(packet_hash, destination_hash, public_key, app_data = None):
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if len(public_key) != Identity.KEYSIZE//8:
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raise TypeError("Can't remember "+RNS.prettyhexrep(destination_hash)+", the public key size of "+str(len(public_key))+" is not valid.", RNS.LOG_ERROR)
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else:
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Identity.known_destinations[destination_hash] = [time.time(), packet_hash, public_key, app_data]
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@staticmethod
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def recall(destination_hash):
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"""
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Recall identity for a destination hash.
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:param destination_hash: Destination hash as *bytes*.
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:returns: An :ref:`RNS.Identity<api-identity>` instance that can be used to create an outgoing :ref:`RNS.Destination<api-destination>`, or *None* if the destination is unknown.
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"""
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if destination_hash in Identity.known_destinations:
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identity_data = Identity.known_destinations[destination_hash]
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identity = Identity(create_keys=False)
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identity.load_public_key(identity_data[2])
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identity.app_data = identity_data[3]
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return identity
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else:
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return None
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@staticmethod
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def recall_app_data(destination_hash):
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"""
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Recall last heard app_data for a destination hash.
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:param destination_hash: Destination hash as *bytes*.
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:returns: *Bytes* containing app_data, or *None* if the destination is unknown.
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"""
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if destination_hash in Identity.known_destinations:
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app_data = Identity.known_destinations[destination_hash][3]
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return app_data
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else:
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return None
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@staticmethod
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def save_known_destinations():
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RNS.log("Saving known destinations to storage...", RNS.LOG_VERBOSE)
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file = open(RNS.Reticulum.storagepath+"/known_destinations","wb")
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umsgpack.dump(Identity.known_destinations, file)
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file.close()
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RNS.log("Done saving known destinations to storage", RNS.LOG_VERBOSE)
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@staticmethod
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def load_known_destinations():
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if os.path.isfile(RNS.Reticulum.storagepath+"/known_destinations"):
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try:
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file = open(RNS.Reticulum.storagepath+"/known_destinations","rb")
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Identity.known_destinations = umsgpack.load(file)
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file.close()
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RNS.log("Loaded "+str(len(Identity.known_destinations))+" known destination from storage", RNS.LOG_VERBOSE)
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except:
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RNS.log("Error loading known destinations from disk, file will be recreated on exit", RNS.LOG_ERROR)
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else:
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RNS.log("Destinations file does not exist, so no known destinations loaded", RNS.LOG_VERBOSE)
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@staticmethod
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def full_hash(data):
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"""
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Get a SHA-256 hash of passed data.
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:param data: Data to be hashed as *bytes*.
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:returns: SHA-256 hash as *bytes*
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"""
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digest = hashes.Hash(hashes.SHA256(), backend=default_backend())
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digest.update(data)
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return digest.finalize()
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@staticmethod
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def truncated_hash(data):
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"""
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Get a truncated SHA-256 hash of passed data.
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:param data: Data to be hashed as *bytes*.
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:returns: Truncated SHA-256 hash as *bytes*
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"""
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return Identity.full_hash(data)[:(Identity.TRUNCATED_HASHLENGTH//8)]
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@staticmethod
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def get_random_hash():
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"""
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Get a random SHA-256 hash.
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:param data: Data to be hashed as *bytes*.
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:returns: Truncated SHA-256 hash of random data as *bytes*
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"""
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return Identity.truncated_hash(os.urandom(10))
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@staticmethod
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def validate_announce(packet):
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if packet.packet_type == RNS.Packet.ANNOUNCE:
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RNS.log("Validating announce from "+RNS.prettyhexrep(packet.destination_hash), RNS.LOG_DEBUG)
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destination_hash = packet.destination_hash
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public_key = packet.data[:Identity.KEYSIZE//8]
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random_hash = packet.data[Identity.KEYSIZE//8:Identity.KEYSIZE//8+10]
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signature = packet.data[Identity.KEYSIZE//8+10:Identity.KEYSIZE//8+10+Identity.KEYSIZE//8]
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app_data = b""
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if len(packet.data) > Identity.KEYSIZE//8+10+Identity.KEYSIZE//8:
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app_data = packet.data[Identity.KEYSIZE//8+10+Identity.KEYSIZE//8:]
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signed_data = destination_hash+public_key+random_hash+app_data
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if not len(packet.data) > Identity.KEYSIZE//8+10+Identity.KEYSIZE//8:
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app_data = None
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announced_identity = Identity(create_keys=False)
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announced_identity.load_public_key(public_key)
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if announced_identity.pub != None and announced_identity.validate(signature, signed_data):
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RNS.Identity.remember(packet.get_hash(), destination_hash, public_key, app_data)
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RNS.log("Stored valid announce from "+RNS.prettyhexrep(destination_hash), RNS.LOG_DEBUG)
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del announced_identity
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return True
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else:
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RNS.log("Received invalid announce", RNS.LOG_DEBUG)
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del announced_identity
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return False
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@staticmethod
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def exit_handler():
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Identity.save_known_destinations()
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@staticmethod
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def from_bytes(prv_bytes):
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"""
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Create a new :ref:`RNS.Identity<api-identity>` instance from *bytes* of private key.
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Can be used to load previously created and saved identities into Reticulum.
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:param prv_bytes: The *bytes* of private a saved private key. **HAZARD!** Never use this to generate a new key by feeding random data in prv_bytes.
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:returns: A :ref:`RNS.Identity<api-identity>` instance, or *None* if the *bytes* data was invalid.
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"""
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identity = Identity(create_keys=False)
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if identity.load_private_key(prv_bytes):
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return identity
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else:
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return None
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@staticmethod
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def from_file(path):
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"""
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Create a new :ref:`RNS.Identity<api-identity>` instance from a file.
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Can be used to load previously created and saved identities into Reticulum.
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:param path: The full path to the saved :ref:`RNS.Identity<api-identity>` data
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:returns: A :ref:`RNS.Identity<api-identity>` instance, or *None* if the loaded data was invalid.
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"""
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identity = Identity(create_keys=False)
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if identity.load(path):
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return identity
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else:
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return None
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def to_file(self, path):
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"""
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Saves the identity to a file. This will write the private key to disk,
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and anyone with access to this file will be able to decrypt all
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communication for the identity. Be very careful with this method.
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:param path: The full path specifying where to save the identity.
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:returns: True if the file was saved, otherwise False.
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"""
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try:
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with open(path, "wb") as key_file:
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key_file.write(self.get_private_key())
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return True
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return False
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except Exception as e:
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RNS.log("Error while saving identity to "+str(path), RNS.LOG_ERROR)
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RNS.log("The contained exception was: "+str(e))
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def __init__(self,create_keys=True):
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# Initialize keys to none
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self.prv = None
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self.prv_bytes = None
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self.sig_prv = None
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self.sig_prv_bytes = None
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self.pub = None
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self.pub_bytes = None
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self.sig_pub = None
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self.sig_pub_bytes = None
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self.hash = None
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self.hexhash = None
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if create_keys:
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self.create_keys()
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def create_keys(self):
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self.prv = X25519PrivateKey.generate()
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self.prv_bytes = self.prv.private_bytes(
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encoding=serialization.Encoding.Raw,
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format=serialization.PrivateFormat.Raw,
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encryption_algorithm=serialization.NoEncryption()
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)
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self.sig_prv = Ed25519PrivateKey.generate()
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self.sig_prv_bytes = self.sig_prv.private_bytes(
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encoding=serialization.Encoding.Raw,
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format=serialization.PrivateFormat.Raw,
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encryption_algorithm=serialization.NoEncryption()
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)
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self.pub = self.prv.public_key()
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self.pub_bytes = self.pub.public_bytes(
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encoding=serialization.Encoding.Raw,
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format=serialization.PublicFormat.Raw
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)
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self.sig_pub = self.sig_prv.public_key()
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self.sig_pub_bytes = self.sig_pub.public_bytes(
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encoding=serialization.Encoding.Raw,
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format=serialization.PublicFormat.Raw
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)
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self.update_hashes()
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RNS.log("Identity keys created for "+RNS.prettyhexrep(self.hash), RNS.LOG_VERBOSE)
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def get_private_key(self):
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"""
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:returns: The private key as *bytes*
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"""
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return self.prv_bytes+self.sig_prv_bytes
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def get_public_key(self):
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"""
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:returns: The public key as *bytes*
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"""
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return self.pub_bytes+self.sig_pub_bytes
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def load_private_key(self, prv_bytes):
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"""
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Load a private key into the instance.
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:param prv_bytes: The private key as *bytes*.
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:returns: True if the key was loaded, otherwise False.
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"""
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try:
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self.prv_bytes = prv_bytes[:Identity.KEYSIZE//8//2]
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self.prv = X25519PrivateKey.from_private_bytes(self.prv_bytes)
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self.sig_prv_bytes = prv_bytes[Identity.KEYSIZE//8//2:]
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self.sig_prv = Ed25519PrivateKey.from_private_bytes(self.sig_prv_bytes)
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self.pub = self.prv.public_key()
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self.pub_bytes = self.pub.public_bytes(
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encoding=serialization.Encoding.Raw,
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format=serialization.PublicFormat.Raw
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)
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self.sig_pub = self.sig_prv.public_key()
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self.sig_pub_bytes = self.sig_pub.public_bytes(
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encoding=serialization.Encoding.Raw,
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format=serialization.PublicFormat.Raw
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)
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self.update_hashes()
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return True
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except Exception as e:
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raise e
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RNS.log("Failed to load identity key", RNS.LOG_ERROR)
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RNS.log("The contained exception was: "+str(e), RNS.LOG_ERROR)
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return False
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def load_public_key(self, pub_bytes):
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"""
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Load a public key into the instance.
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:param pub_bytes: The public key as *bytes*.
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:returns: True if the key was loaded, otherwise False.
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"""
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try:
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self.pub_bytes = pub_bytes[:Identity.KEYSIZE//8//2]
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self.sig_pub_bytes = pub_bytes[Identity.KEYSIZE//8//2:]
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self.pub = X25519PublicKey.from_public_bytes(self.pub_bytes)
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self.sig_pub = Ed25519PublicKey.from_public_bytes(self.sig_pub_bytes)
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self.update_hashes()
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except Exception as e:
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RNS.log("Error while loading public key, the contained exception was: "+str(e), RNS.LOG_ERROR)
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def update_hashes(self):
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self.hash = Identity.truncated_hash(self.get_public_key())
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self.hexhash = self.hash.hex()
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def load(self, path):
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try:
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with open(path, "rb") as key_file:
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prv_bytes = key_file.read()
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return self.load_private_key(prv_bytes)
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return False
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except Exception as e:
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RNS.log("Error while loading identity from "+str(path), RNS.LOG_ERROR)
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RNS.log("The contained exception was: "+str(e))
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def get_salt(self):
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return self.hash
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def get_context(self):
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return None
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def encrypt(self, plaintext):
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"""
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Encrypts information for the identity.
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:param plaintext: The plaintext to be encrypted as *bytes*.
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:returns: Ciphertext token as *bytes*.
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:raises: *KeyError* if the instance does not hold a public key.
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"""
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if self.pub != None:
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ephemeral_key = X25519PrivateKey.generate()
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ephemeral_pub_bytes = ephemeral_key.public_key().public_bytes(
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encoding=serialization.Encoding.Raw,
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format=serialization.PublicFormat.Raw
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)
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shared_key = ephemeral_key.exchange(self.pub)
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derived_key = derived_key = HKDF(
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algorithm=hashes.SHA256(),
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length=32,
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salt=self.get_salt(),
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info=self.get_context(),
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).derive(shared_key)
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fernet = Fernet(base64.urlsafe_b64encode(derived_key))
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ciphertext = base64.urlsafe_b64decode(fernet.encrypt(plaintext))
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token = ephemeral_pub_bytes+ciphertext
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return token
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else:
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raise KeyError("Encryption failed because identity does not hold a public key")
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def decrypt(self, ciphertext_token):
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"""
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Decrypts information for the identity.
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:param ciphertext: The ciphertext to be decrypted as *bytes*.
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:returns: Plaintext as *bytes*, or *None* if decryption fails.
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:raises: *KeyError* if the instance does not hold a private key.
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"""
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if self.prv != None:
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if len(ciphertext_token) > Identity.KEYSIZE//8//2:
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plaintext = None
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try:
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peer_pub_bytes = ciphertext_token[:Identity.KEYSIZE//8//2]
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peer_pub = X25519PublicKey.from_public_bytes(peer_pub_bytes)
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shared_key = self.prv.exchange(peer_pub)
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derived_key = derived_key = HKDF(
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algorithm=hashes.SHA256(),
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length=32,
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salt=self.get_salt(),
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info=self.get_context(),
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).derive(shared_key)
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fernet = Fernet(base64.urlsafe_b64encode(derived_key))
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ciphertext = ciphertext_token[Identity.KEYSIZE//8//2:]
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plaintext = fernet.decrypt(base64.urlsafe_b64encode(ciphertext))
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except Exception as e:
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RNS.log("Decryption by "+RNS.prettyhexrep(self.hash)+" failed: "+str(e), RNS.LOG_DEBUG)
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return plaintext;
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else:
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RNS.log("Decryption failed because the token size was invalid.", RNS.LOG_DEBUG)
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return None
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else:
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raise KeyError("Decryption failed because identity does not hold a private key")
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def sign(self, message):
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"""
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Signs information by the identity.
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:param message: The message to be signed as *bytes*.
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:returns: Signature as *bytes*.
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:raises: *KeyError* if the instance does not hold a private key.
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"""
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if self.sig_prv != None:
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try:
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return self.sig_prv.sign(message)
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except Exception as e:
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RNS.log("The identity "+str(self)+" could not sign the requested message. The contained exception was: "+str(e), RNS.LOG_ERROR)
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raise e
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else:
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raise KeyError("Signing failed because identity does not hold a private key")
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def validate(self, signature, message):
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"""
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Validates the signature of a signed message.
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:param signature: The signature to be validated as *bytes*.
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:param message: The message to be validated as *bytes*.
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:returns: True if the signature is valid, otherwise False.
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:raises: *KeyError* if the instance does not hold a public key.
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"""
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if self.pub != None:
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try:
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self.sig_pub.verify(signature, message)
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return True
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except Exception as e:
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return False
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else:
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raise KeyError("Signature validation failed because identity does not hold a public key")
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def prove(self, packet, destination=None):
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signature = self.sign(packet.packet_hash)
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if RNS.Reticulum.should_use_implicit_proof():
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proof_data = signature
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else:
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proof_data = packet.packet_hash + signature
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if destination == None:
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destination = packet.generate_proof_destination()
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proof = RNS.Packet(destination, proof_data, RNS.Packet.PROOF, attached_interface = packet.receiving_interface)
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proof.send()
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def __str__(self):
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return RNS.prettyhexrep(self.hash)
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