Reticulum/FPE/Identity.py

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2018-03-16 10:40:37 +00:00
import base64
import math
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.primitives.asymmetric import padding
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class Identity:
# Configure key size
KEYSIZE = 1536;
# Padding size, not configurable
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PADDINGSIZE= 336;
def __init__(self):
# Initialize keys to none
self.prv = None
self.pub = None
self.prv_bytes = None
self.pub_bytes = None
self.hash = None
self.hexhash = None
self.createKeys()
@staticmethod
def getHash(pub_key):
digest = hashes.Hash(hashes.SHA256(), backend=default_backend())
digest.update(pub_key)
return digest.finalize()[:10]
def createKeys(self):
self.prv = rsa.generate_private_key(
public_exponent=65337,
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
)
self.hash = Identity.getHash(self.pub_bytes)
self.hexhash = self.hash.encode("hex_codec")
print("Identity keys created, private length is "+str(len(self.prv_bytes)))
print("Identity keys created, public length is "+str(len(self.pub_bytes)))
def getPrivateKey(self):
return self.prv_bytes
def getPublicKey(self):
return self.pub_bytes
def loadPrivateKey(self, key):
self.prv_bytes = key
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
)
def loadPublicKey(self, key):
self.pub_bytes = key
self.pub = load_der_public_key(self.pub_bytes, backend=default_backend())
def saveIdentity(self):
pass
def loadIdentity(self):
pass
def encrypt(self, plaintext):
if self.prv != None:
chunksize = (Identity.KEYSIZE-Identity.PADDINGSIZE)/8
chunks = int(math.ceil(len(plaintext)/(float(chunksize))))
print("Plaintext size is "+str(len(plaintext))+", with "+str(chunks)+" chunks")
ciphertext = "";
for chunk in range(chunks):
start = chunk*chunksize
end = (chunk+1)*chunksize
if (chunk+1)*chunksize > len(plaintext):
end = len(plaintext)
print("Processing chunk "+str(chunk+1)+" of "+str(chunks)+". Starting at "+str(start)+" and stopping at "+str(end)+". The length is "+str(len(plaintext[start:end])))
ciphertext += self.pub.encrypt(
plaintext[start:end],
padding.OAEP(
mgf=padding.MGF1(algorithm=hashes.SHA1()),
algorithm=hashes.SHA1(),
label=None
)
)
print("Plaintext encrypted, ciphertext length is "+str(len(ciphertext))+" bytes.")
return ciphertext
else:
raise KeyError("Encryption failed because identity does not hold a private key")
def decrypt(self, ciphertext):
if self.prv != None:
print("Ciphertext length is "+str(len(ciphertext))+". ")
chunksize = (Identity.KEYSIZE)/8
chunks = int(math.ceil(len(ciphertext)/(float(chunksize))))
plaintext = "";
for chunk in range(chunks):
start = chunk*chunksize
end = (chunk+1)*chunksize
if (chunk+1)*chunksize > len(ciphertext):
end = len(ciphertext)
print("Processing chunk "+str(chunk+1)+" of "+str(chunks)+". Starting at "+str(start)+" and stopping at "+str(end)+". The length is "+str(len(ciphertext[start:end])))
plaintext += self.prv.decrypt(
ciphertext[start:end],
padding.OAEP(
mgf=padding.MGF1(algorithm=hashes.SHA1()),
algorithm=hashes.SHA1(),
label=None
)
)
return plaintext;
else:
raise KeyError("Decryption failed because identity does not hold a private key")
def sign(self, message):
if self.prv != None:
signer = self.prv.signer(
padding.PSS(
mgf=padding.MGF1(hashes.SHA256()),
salt_length=padding.PSS.MAX_LENGTH
),
hashes.SHA256()
)
signer.update(message)
return signer.finalize()
else:
raise KeyError("Signing failed because identity does not hold a private key")