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