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32 lines
1001 B
Python
32 lines
1001 B
Python
import hashlib
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from secp256k1 import PublicKey
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def hash_to_point_pre_0_3_3(secret_msg):
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"""
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NOTE: Clients pre 0.3.3 used a different hash_to_curve
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Generates x coordinate from the message hash and checks if the point lies on the curve.
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If it does not, it tries computing again a new x coordinate from the hash of the coordinate.
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"""
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point = None
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msg = secret_msg
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while point is None:
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_hash = hashlib.sha256(msg).hexdigest().encode("utf-8")
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try:
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# We construct compressed pub which has x coordinate encoded with even y
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_hash = list(_hash[:33]) # take the 33 bytes and get a list of bytes
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_hash[0] = 0x02 # set first byte to represent even y coord
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_hash = bytes(_hash)
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point = PublicKey(_hash, raw=True)
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except:
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msg = _hash
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return point
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def verify_pre_0_3_3(a, C, secret_msg):
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Y = hash_to_point_pre_0_3_3(secret_msg.encode("utf-8"))
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return C == Y.mult(a)
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