Reticulum/RNS/Identity.py

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import base64
import math
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import os
import RNS
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import time
import atexit
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from .vendor import umsgpack as umsgpack
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from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
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from cryptography.hazmat.primitives.serialization import load_der_public_key
from cryptography.hazmat.primitives.serialization import load_der_private_key
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from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.primitives.asymmetric import padding
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class Identity:
"""
This class is used to manage identities in Reticulum. It provides methods
for encryption, decryption, signatures and verification, and is the basis
for all encrypted communication over Reticulum networks.
:param public_only: Specifies whether this destination only holds a public key.
"""
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KEYSIZE = 1024
"""
RSA key size in bits.
"""
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DERKEYSIZE = KEYSIZE+272
# Non-configurable constants
PADDINGSIZE = 336 # In bits
HASHLENGTH = 256 # In bits
SIGLENGTH = KEYSIZE
ENCRYPT_CHUNKSIZE = (KEYSIZE-PADDINGSIZE)//8
DECRYPT_CHUNKSIZE = KEYSIZE//8
TRUNCATED_HASHLENGTH = 80 # In bits
"""
Constant specifying the truncated hash length (in bits) used by Reticulum
for addressable hashes. Non-configurable.
"""
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# Storage
known_destinations = {}
@staticmethod
def remember(packet_hash, destination_hash, public_key, app_data = None):
Identity.known_destinations[destination_hash] = [time.time(), packet_hash, public_key, app_data]
@staticmethod
def recall(destination_hash):
"""
Recall identity for a destination hash.
:param destination_hash: Destination hash as *bytes*.
: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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RNS.log("Searching for "+RNS.prettyhexrep(destination_hash)+"...", RNS.LOG_EXTREME)
if destination_hash in Identity.known_destinations:
identity_data = Identity.known_destinations[destination_hash]
identity = Identity(public_only=True)
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identity.load_public_key(identity_data[2])
identity.app_data = identity_data[3]
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RNS.log("Found "+RNS.prettyhexrep(destination_hash)+" in known destinations", RNS.LOG_EXTREME)
return identity
else:
RNS.log("Could not find "+RNS.prettyhexrep(destination_hash)+" in known destinations", RNS.LOG_EXTREME)
return None
@staticmethod
def recall_app_data(destination_hash):
"""
Recall last heard app_data for a destination hash.
:param destination_hash: Destination hash as *bytes*.
:returns: *Bytes* containing app_data, or *None* if the destination is unknown.
"""
RNS.log("Searching for app_data for "+RNS.prettyhexrep(destination_hash)+"...", RNS.LOG_EXTREME)
if destination_hash in Identity.known_destinations:
app_data = Identity.known_destinations[destination_hash][3]
RNS.log("Found "+RNS.prettyhexrep(destination_hash)+" app_data in known destinations", RNS.LOG_EXTREME)
return app_data
else:
RNS.log("Could not find "+RNS.prettyhexrep(destination_hash)+" app_data in known destinations", RNS.LOG_EXTREME)
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)
file = open(RNS.Reticulum.storagepath+"/known_destinations","wb")
umsgpack.dump(Identity.known_destinations, file)
file.close()
RNS.log("Done saving known destinations to storage", RNS.LOG_VERBOSE)
@staticmethod
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def load_known_destinations():
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if os.path.isfile(RNS.Reticulum.storagepath+"/known_destinations"):
try:
file = open(RNS.Reticulum.storagepath+"/known_destinations","rb")
Identity.known_destinations = umsgpack.load(file)
file.close()
RNS.log("Loaded "+str(len(Identity.known_destinations))+" known destination from storage", RNS.LOG_VERBOSE)
except:
RNS.log("Error loading known destinations from disk, file will be recreated on exit", RNS.LOG_ERROR)
else:
RNS.log("Destinations file does not exist, so no known destinations loaded", RNS.LOG_VERBOSE)
@staticmethod
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def full_hash(data):
"""
Get a SHA-256 hash of passed data.
:param data: Data to be hashed as *bytes*.
:returns: SHA-256 hash as *bytes*
"""
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digest = hashes.Hash(hashes.SHA256(), backend=default_backend())
digest.update(data)
return digest.finalize()
@staticmethod
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def truncated_hash(data):
"""
Get a truncated SHA-256 hash of passed data.
:param data: Data to be hashed as *bytes*.
:returns: Truncated SHA-256 hash as *bytes*
"""
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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():
"""
Get a random SHA-256 hash.
:param data: Data to be hashed as *bytes*.
:returns: Truncated SHA-256 hash of random data as *bytes*
"""
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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:
RNS.log("Validating announce from "+RNS.prettyhexrep(packet.destination_hash), RNS.LOG_DEBUG)
destination_hash = packet.destination_hash
public_key = packet.data[10:Identity.DERKEYSIZE//8+10]
random_hash = packet.data[Identity.DERKEYSIZE//8+10:Identity.DERKEYSIZE//8+20]
signature = packet.data[Identity.DERKEYSIZE//8+20:Identity.DERKEYSIZE//8+20+Identity.KEYSIZE//8]
app_data = b""
if len(packet.data) > Identity.DERKEYSIZE//8+20+Identity.KEYSIZE//8:
app_data = packet.data[Identity.DERKEYSIZE//8+20+Identity.KEYSIZE//8:]
signed_data = destination_hash+public_key+random_hash+app_data
if not len(packet.data) > Identity.DERKEYSIZE//8+20+Identity.KEYSIZE//8:
app_data = None
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announced_identity = Identity(public_only=True)
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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):
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)
del announced_identity
return True
else:
RNS.log("Received invalid announce", RNS.LOG_DEBUG)
del announced_identity
return False
@staticmethod
def exit_handler():
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Identity.save_known_destinations()
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@staticmethod
def from_file(path):
"""
Create a new :ref:`RNS.Identity<api-identity>` instance from a file.
Can be used to load previously created and saved identities into Reticulum.
:param path: The full path to the saved :ref:`RNS.Identity<api-identity>` data
:returns: A :ref:`RNS.Identity<api-identity>` instance, or *None* if the loaded data was invalid.
"""
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identity = Identity(public_only=True)
if identity.load(path):
return identity
else:
return None
def __init__(self,public_only=False):
# Initialize keys to none
self.prv = None
self.pub = None
self.prv_bytes = None
self.pub_bytes = None
self.hash = None
self.hexhash = None
if not public_only:
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self.create_keys()
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def create_keys(self):
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self.prv = rsa.generate_private_key(
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public_exponent=65537,
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key_size=Identity.KEYSIZE,
backend=default_backend()
)
self.prv_bytes = self.prv.private_bytes(
encoding=serialization.Encoding.DER,
format=serialization.PrivateFormat.PKCS8,
encryption_algorithm=serialization.NoEncryption()
)
self.pub = self.prv.public_key()
self.pub_bytes = self.pub.public_bytes(
encoding=serialization.Encoding.DER,
format=serialization.PublicFormat.SubjectPublicKeyInfo
)
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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):
"""
:returns: The private key as *bytes*
"""
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return self.prv_bytes
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def get_public_key(self):
"""
:returns: The public key as *bytes*
"""
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return self.pub_bytes
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def load_private_key(self, prv_bytes):
"""
Load a private key into the instance.
:param prv_bytes: The private key as *bytes*.
:returns: True if the key was loaded, otherwise False.
"""
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try:
self.prv_bytes = prv_bytes
self.prv = serialization.load_der_private_key(
self.prv_bytes,
password=None,
backend=default_backend()
)
self.pub = self.prv.public_key()
self.pub_bytes = self.pub.public_bytes(
encoding=serialization.Encoding.DER,
format=serialization.PublicFormat.SubjectPublicKeyInfo
)
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self.update_hashes()
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return True
except Exception as e:
RNS.log("Failed to load identity key", RNS.LOG_ERROR)
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, key):
"""
Load a public key into the instance.
:param prv_bytes: The public key as *bytes*.
:returns: True if the key was loaded, otherwise False.
"""
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try:
self.pub_bytes = key
self.pub = load_der_public_key(self.pub_bytes, backend=default_backend())
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self.update_hashes()
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except Exception as e:
RNS.log("Error while loading public key, the contained exception was: "+str(e), RNS.LOG_ERROR)
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def update_hashes(self):
self.hash = Identity.truncated_hash(self.pub_bytes)
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self.hexhash = self.hash.hex()
def to_file(self, path):
"""
Saves the identity to a file. This will write the private key to disk,
and anyone with access to this file will be able to decrypt all
communication for the identity. Be very careful with this method.
:param path: The full path specifying where to save the identity.
:returns: True if the file was saved, otherwise False.
"""
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try:
with open(path, "wb") as key_file:
key_file.write(self.prv_bytes)
return True
return False
except Exception as e:
RNS.log("Error while saving identity to "+str(path), RNS.LOG_ERROR)
RNS.log("The contained exception was: "+str(e))
def load(self, path):
try:
with open(path, "rb") as key_file:
prv_bytes = key_file.read()
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return self.load_private_key(prv_bytes)
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return False
except Exception as e:
RNS.log("Error while loading identity from "+str(path), RNS.LOG_ERROR)
RNS.log("The contained exception was: "+str(e))
def encrypt(self, plaintext):
"""
Encrypts information for the identity.
:param plaintext: The plaintext to be encrypted as *bytes*.
:returns: Ciphertext as *bytes*.
:raises: *KeyError* if the instance does not hold a public key
"""
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if self.pub != None:
chunksize = Identity.ENCRYPT_CHUNKSIZE
chunks = int(math.ceil(len(plaintext)/(float(chunksize))))
ciphertext = b"";
for chunk in range(chunks):
start = chunk*chunksize
end = (chunk+1)*chunksize
if (chunk+1)*chunksize > len(plaintext):
end = len(plaintext)
ciphertext += self.pub.encrypt(
plaintext[start:end],
padding.OAEP(
mgf=padding.MGF1(algorithm=hashes.SHA1()),
algorithm=hashes.SHA1(),
label=None
)
)
return ciphertext
else:
raise KeyError("Encryption failed because identity does not hold a public key")
def decrypt(self, ciphertext):
"""
Decrypts information for the identity.
:param ciphertext: The ciphertext to be decrypted as *bytes*.
:returns: Plaintext as *bytes*, or *None* if decryption fails.
:raises: *KeyError* if the instance does not hold a private key
"""
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if self.prv != None:
plaintext = None
try:
chunksize = Identity.DECRYPT_CHUNKSIZE
chunks = int(math.ceil(len(ciphertext)/(float(chunksize))))
plaintext = b"";
for chunk in range(chunks):
start = chunk*chunksize
end = (chunk+1)*chunksize
if (chunk+1)*chunksize > len(ciphertext):
end = len(ciphertext)
plaintext += self.prv.decrypt(
ciphertext[start:end],
padding.OAEP(
mgf=padding.MGF1(algorithm=hashes.SHA1()),
algorithm=hashes.SHA1(),
label=None
)
)
except:
RNS.log("Decryption by "+RNS.prettyhexrep(self.hash)+" failed", RNS.LOG_VERBOSE)
return plaintext;
else:
raise KeyError("Decryption failed because identity does not hold a private key")
def sign(self, message):
"""
Signs information by the identity.
:param message: The message to be signed as *bytes*.
:returns: Signature as *bytes*.
:raises: *KeyError* if the instance does not hold a private key
"""
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if self.prv != None:
signature = self.prv.sign(
message,
padding.PSS(
mgf=padding.MGF1(hashes.SHA256()),
salt_length=padding.PSS.MAX_LENGTH
),
hashes.SHA256()
)
return signature
else:
raise KeyError("Signing failed because identity does not hold a private key")
def validate(self, signature, message):
"""
Validates the signature of a signed message.
:param signature: The signature to be validated as *bytes*.
:param message: The message to be validated as *bytes*.
:returns: True if the signature is valid, otherwise False.
:raises: *KeyError* if the instance does not hold a public key
"""
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if self.pub != None:
try:
self.pub.verify(
signature,
message,
padding.PSS(
mgf=padding.MGF1(hashes.SHA256()),
salt_length=padding.PSS.MAX_LENGTH
),
hashes.SHA256()
)
return True
except Exception as e:
return False
else:
raise KeyError("Signature validation failed because identity does not hold a public key")
def prove(self, packet, destination=None):
signature = self.sign(packet.packet_hash)
if RNS.Reticulum.should_use_implicit_proof():
proof_data = signature
else:
proof_data = packet.packet_hash + signature
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)
proof.send()
def __str__(self):
return RNS.prettyhexrep(self.hash)