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PyBitmessage/src/helper_ackPayload.py

41 lines
1.7 KiB

import hashlib
import highlevelcrypto
import random
import helper_random
from binascii import hexlify, unhexlify
from struct import pack, unpack
from addresses import encodeVarint
# This function generates payload objects for message acknowledgements
# Several stealth levels are available depending on the privacy needs;
# a higher level means better stealth, but also higher cost (size+POW)
# - level 0: a random 32-byte sequence with a message header appended
# - level 1: a getpubkey request for a (random) dummy key hash
# - level 2: a standard message, encrypted to a random pubkey
def genAckPayload(streamNumber=1, stealthLevel=0):
if (stealthLevel==2): # Generate privacy-enhanced payload
# Generate a dummy privkey and derive the pubkey
dummyPubKeyHex = highlevelcrypto.privToPub(hexlify(helper_random.randomBytes(32)))
# Generate a dummy message of random length
# (the smallest possible standard-formatted message is 234 bytes)
dummyMessage = helper_random.randomBytes(random.randint(234, 800))
# Encrypt the message using standard BM encryption (ECIES)
ackdata = highlevelcrypto.encrypt(dummyMessage, dummyPubKeyHex)
acktype = 2 # message
version = 1
elif (stealthLevel==1): # Basic privacy payload (random getpubkey)
ackdata = helper_random.randomBytes(32)
acktype = 0 # getpubkey
version = 4
else: # Minimum viable payload (non stealth)
ackdata = helper_random.randomBytes(32)
acktype = 2 # message
version = 1
ackobject = pack('>I', acktype) + encodeVarint(version) + encodeVarint(streamNumber) + ackdata
return ackobject