105 lines
2.7 KiB
Python
105 lines
2.7 KiB
Python
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from pyethereum import utils
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import random
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def sha3(x):
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return utils.decode_int(utils.zunpad(utils.sha3(x)))
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class SeedObj():
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def __init__(self, seed):
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self.seed = seed
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self.a = 3**160
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self.c = 7**80
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self.n = 2**256 - 4294968273 # secp256k1n, why not
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def rand(self, r):
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self.seed = (self.seed * self.a + self.c) % self.n
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return self.seed % r
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def encode_int(x):
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o = ''
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for _ in range(8):
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o = chr(x % 256) + o
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x //= 256
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return o
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ops = {
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"plus": lambda x, y: (x + y) % 2**64,
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"times": lambda x, y: (x * y) % 2**64,
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"xor": lambda x, y: x ^ y,
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"and": lambda x, y: x & y,
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"or": lambda x, y: x | y,
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"not": lambda x, y: 2**64-1-x,
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"nxor": lambda x, y: (2**64-1-x) ^ y,
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"rshift": lambda x, y: x >> (y % 64)
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}
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def gentape(W, H, SEED):
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s = SeedObj(SEED)
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tape = []
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for i in range(H):
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op = ops.keys()[s.rand(len(ops))]
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r = s.rand(100)
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if r < 20 and i > 20:
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x1 = tape[-r]["x1"]
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else:
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x1 = s.rand(W)
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x2 = s.rand(W)
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tape.append({"op": op, "x1": x1, "x2": x2})
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return tape
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def runtape(TAPE, SEED, params):
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s = SeedObj(SEED)
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# Fill up tape inputs
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mem = [0] * params["w"]
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for i in range(params["w"]):
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mem[i] = s.rand(2**64)
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# Direction variable (run forwards or backwards)
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dir = 1
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# Run the tape on the inputs
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for i in range(params["h"] // 100):
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for j in (range(100) if dir == 1 else range(99, -1, -1)):
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t = TAPE[i * 100 + j]
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mem[t["x1"]] = ops[t["op"]](mem[t["x1"]], mem[t["x2"]])
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# 16% of the time, we flip the order of the next 100 ops;
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# this adds in conditional branching
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if 2 < mem[t["x1"]] % 37 < 9:
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dir *= -1
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return sha3(''.join(encode_int(x) for x in mem))
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def PoWVerify(header, nonce, params):
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tape = gentape(params["w"], params["h"],
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sha3(header + encode_int(nonce // params["n"])))
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h = runtape(tape, sha3(header + encode_int(nonce)), params)
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print h
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return h < 2**256 / params["diff"]
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def PoWRun(header, params):
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# actual randomness, so that miners don't overlap
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nonce = random.randrange(2**50) * params["n"]
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tape = None
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while 1:
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print nonce
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if nonce % params["n"] == 0:
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tape = gentape(params["w"], params["h"],
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sha3(header + encode_int(nonce // params["n"])))
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h = runtape(tape, sha3(header + encode_int(nonce)), params)
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if h < 2**256 / params["diff"]:
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return nonce
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else:
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nonce += 1
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params = {
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"w": 100,
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"h": 15000, # generally, w*log(w) at least
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"diff": 2**24, # initial
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"n": 1000
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}
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