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# bitcoin midstate calculation

a guest Jan 9th, 2014 192 Never
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1. #!/usr/bin/python
2.
3. # bitcoin midstate calculation, copyright by Frank Buss
4. # call it with the "data" string of a getwork response. Example:
6. # Output: 93c524951367c505ba69e616a010282d376ee807daa9562f69ce5bcd2dda787a
7. # tested with Python 3.3.3 on Windows
8.
9. # some helper functions are from https://github.com/bitcoin/bitcoin/blob/master/contrib/pyminer/pyminer.py
10.
11. from sys import argv
12. from struct import pack, unpack
13. from binascii import unhexlify, hexlify
14.
15. def uint32(x):
16.         return x & 0xffffffff
17.
18. def rotateright(i,p):
19.     """i>>>p"""
20.     p &= 0x1F # p mod 32
21.     return i>>p | ((i<<(32-p)) & 0xFFFFFFFF)
22.
23. def shiftright(i,p):
24.     """i>>p"""
25.     p &= 0x1F # p mod 32
26.     return i>>p
27.
29.     return sum(list(i))&0xFFFFFFFF
30.
31. def CH(e, f, g):
32.         return (e & f) ^ ((~e) & g)
33.
34. def E0(a):
35.         return rotateright(a, 2) ^ rotateright(a, 13) ^ rotateright(a, 22)
36.
37. def E1(e):
38.         return rotateright(e, 6) ^ rotateright(e, 11) ^ rotateright(e, 25)
39.
40. def SIG0(x):
41.         return rotateright(x, 7) ^ rotateright(x, 18) ^ shiftright(x, 3)
42.
43. def SIG1(x):
44.         return rotateright(x, 17) ^ rotateright(x, 19) ^ shiftright(x, 10)
45.
46. def MAJ(a, b, c):
47.         return (a & b) ^ (a & c) ^ (b & c)
48.
49. # test data
50. datastr = argv[1]
51.
52. # convert to binary array
53. data = unhexlify(datastr)
54.
55. # initialize hash values
56. h0 = 0x6a09e667
57. h1 = 0xbb67ae85
58. h2 = 0x3c6ef372
59. h3 = 0xa54ff53a
60. h4 = 0x510e527f
61. h5 = 0x9b05688c
62. h6 = 0x1f83d9ab
63. h7 = 0x5be0cd19
64.
65. # initialize array of round constants
66. K = [
67.         0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
68.         0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
69.         0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
70.         0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
71.         0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
72.         0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
73.         0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
74.         0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
75. ]
76.
77. # copy chunk into first 16 words w[0..15] of the message schedule array
78. w = list(unpack('<IIIIIIIIIIIIIIII', data[:64]))
79.
80. # extend the first 16 words into the remaining 48 words w[16..63] of the message schedule array:
81. w += [0] * 48
82. for i in range(16, 64):
83.         w[i] = addu32(SIG1(w[i-2]), w[i-7], SIG0(w[i-15]), w[i-16])
84.
85.
86. # initialize working variables to current hash value
87. a = h0
88. b = h1
89. c = h2
90. d = h3
91. e = h4
92. f = h5
93. g = h6
94. h = h7
95.
96. # compression function main loop
97. for i in range(64):
98.         t1=addu32(h, E1(e), CH(e,f,g), K[i], w[i])
100.         h=g
101.         g=f
102.         f=e
104.         d=c
105.         c=b
106.         b=a
108.         if i == 0: a0 = a
109.         if i == 1: a1 = a
110.         if i == 2: a2 = a
111.         if i == 0: e0 = e
112.         if i == 1: e1 = e
113.         if i == 2: e2 = e
114.
115. # add the compressed chunk to the current hash value: