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52 lines
1.8 KiB
Python
52 lines
1.8 KiB
Python
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# This is a reference implementation of the COMMIT/REVEAL calculation for
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# prop250. We use it to generate a test vector for the test_encoding()
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# unittest.
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#
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# Here is the computation formula:
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#
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# H = SHA3-256
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# TIMESTAMP = 8 bytes network-endian value
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# RAND = H(32 bytes of random)
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#
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# REVEAL = base64-encode( TIMESTAMP || RAND )
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# COMMIT = base64-encode( TIMESTAMP || H(REVEAL) )
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#
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import sys
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import hashlib
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import struct
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import base64
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# Python 3.6+, the SHA3 is available in hashlib natively. Else this requires
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# the pysha3 package (pip install pysha3).
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if sys.version_info < (3, 6):
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import sha3
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# Test vector to make sure the right sha3 version will be used. pysha3 < 1.0
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# used the old Keccak implementation. During the finalization of SHA3, NIST
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# changed the delimiter suffix from 0x01 to 0x06. The Keccak sponge function
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# stayed the same. pysha3 1.0 provides the previous Keccak hash, too.
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TEST_VALUE = "e167f68d6563d75bb25f3aa49c29ef612d41352dc00606de7cbd630bb2665f51"
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if TEST_VALUE != sha3.sha3_256(b"Hello World").hexdigest():
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print("pysha3 version is < 1.0. Please install from:")
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print("https://github.com/tiran/pysha3https://github.com/tiran/pysha3")
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sys.exit(1)
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# TIMESTAMP
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ts = 1454333590
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# RAND
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data = 'A' * 32 # Yes very very random, NIST grade :).
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rand = hashlib.sha3_256(data)
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reveal = struct.pack('!Q', ts) + rand.digest()
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b64_reveal = base64.b64encode(reveal)
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print("REVEAL: %s" % (b64_reveal))
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# Yes we do hash the _encoded_ reveal here that is H(REVEAL)
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hashed_reveal = hashlib.sha3_256(b64_reveal)
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commit = struct.pack('!Q', ts) + hashed_reveal.digest()
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print("COMMIT: %s" % (base64.b64encode(commit)))
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# REVEAL: AAAAAFavXpZJxbwTupvaJCTeIUCQmOPxAMblc7ChL5H2nZKuGchdaA==
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# COMMIT: AAAAAFavXpbkBMzMQG7aNoaGLFNpm2Wkk1ozXhuWWqL//GynltxVAg==
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