29 lines
631 B
Python
29 lines
631 B
Python
from hashlib import sha256
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ZERO_BYTES32 = b'\x00' * 32
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def _hash(x):
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return sha256(x).digest()
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# Minimal collection of (key, value) pairs, for fast hash-retrieval, to save on repetitive computation cost.
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# Key = the hash input
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# Value = the hash output
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hash_cache = []
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def add_zero_hashes_to_cache():
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zerohashes = [(None, ZERO_BYTES32)]
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for layer in range(1, 32):
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k = zerohashes[layer - 1][1] + zerohashes[layer - 1][1]
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zerohashes.append((k, _hash(k)))
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hash_cache.extend(zerohashes[1:])
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def hash(x):
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for (k, h) in hash_cache:
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if x == k:
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return h
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return _hash(x)
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