Posted on 2022/01/04, 7:03 PM By admin22
ブロックチェーンにはネットワークを安定に維持するしくみが多くあり、技術的にとても興味深い題材ばかりです。
過去に書いた、ビットコイン論文ついての記事
その中でマイニングと呼ばれるしくみはとても秀逸にできています。
参考書籍) 「ビットコインとブロックチェーン(Mastering Bitcoin)」(NTT出版)
ここではProof-of-Workとよばれるハッシュ計算を実際に動かしてみました。
マイナーが多数いようと少数だろうと約10分で新しいブロックが作り出せるように、計算にかかる難易度をコントロールしています。
Difficulty Targetと呼ばれる値よりも小さいハッシュ値がでるようにnonceを変えながらトライし、見つけたら正解という単純なものですが、このTarget値が1bit変わるだけで、劇的に計算量が変化します。
これをPythonで実装されたサンプルを出力を見やすくして実行してみました。
オリジナル) https://github.com/bitcoinbook/bitcoinbook/blob/develop/code/proof-of-work-example.py
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 |
#!/usr/bin/env python # example of proof-of-work algorithm import hashlib import time try: long # Python 2 xrange except NameError: long = int # Python 3 xrange = range max_nonce = 2 ** 32 # 4 billion def proof_of_work(header, difficulty_bits): target = 2 ** (256 - difficulty_bits) for nonce in xrange(max_nonce): hash_result = hashlib.sha256((str(header) + str(nonce)).encode()).hexdigest() # check if this is a valid result, equal to or below the target if long(hash_result, 16) <= target: print("Nonce: %d" % nonce) print("Hash: %s" % hash_result) print("Target: {:064X}".format(target)) return (hash_result, nonce) print("Failed after %d (max_nonce) tries" % nonce) return nonce if __name__ == '__main__': nonce = 0 hash_result = '' # difficulty from 0 to 31 bits for difficulty_bits in xrange(32): print("Difficulty: %d bits" % difficulty_bits) # checkpoint the current time start_time = time.time() # make a new block which includes the hash from the previous block # we fake a block of transactions - just a string new_block = 'test block with transactions' + hash_result # find a valid nonce for the new block (hash_result, nonce) = proof_of_work(new_block, difficulty_bits) # checkpoint how long it took to find a result end_time = time.time() elapsed_time = end_time - start_time print("Elapsed Time: %.4f seconds" % elapsed_time) if elapsed_time > 0: # estimate the hashes per second hash_power = float(long(nonce) / elapsed_time) print("Hashing Power: %ld hashes per second" % hash_power) print("") |
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 |
% python proof-of-work-example.py Difficulty: 0 bits Nonce: 0 Hash: ff8253ed10b5f719d52a709a66af8cd5e2054f702e675af4ca0cae70f0988634 Target: 10000000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0005 seconds Hashing Power: 0 hashes per second Difficulty: 1 bits Nonce: 0 Hash: 22c608547e239faf5c353e7ebd204042760b93891d1d0be9ab488d36c73c077b Target: 8000000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0000 seconds Hashing Power: 0 hashes per second Difficulty: 2 bits Nonce: 2 Hash: 0635f41cdb98c6e73516f84fc88da19a13a3bac6298dbfc0df5170bac93ba4dd Target: 4000000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0000 seconds Hashing Power: 95325 hashes per second Difficulty: 3 bits Nonce: 9 Hash: 1c1c105e65b47142f028a8f93ddf3dabb9260491bc64474738133ce5256cb3c1 Target: 2000000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0000 seconds Hashing Power: 224694 hashes per second Difficulty: 4 bits Nonce: 25 Hash: 0f7becfd3bcd1a82e06663c97176add89e7cae0268de46f94e7e11bc3863e148 Target: 1000000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0001 seconds Hashing Power: 284166 hashes per second Difficulty: 5 bits Nonce: 36 Hash: 029ae6e5004302a120630adcbb808452346ab1cf0b94c5189ba8bac1d47e7903 Target: 0800000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0001 seconds Hashing Power: 294912 hashes per second Difficulty: 6 bits Nonce: 0 Hash: 0083214fa878cea749bd07bd77e92b311be876dd72f3d4924d5ae4ead54febe5 Target: 0400000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0000 seconds Hashing Power: 0 hashes per second Difficulty: 7 bits Nonce: 26 Hash: 00f7abab177613afc42270e3f5f79ffddd694093030663b32fe26ce2a377a993 Target: 0200000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0001 seconds Hashing Power: 286225 hashes per second Difficulty: 8 bits Nonce: 33 Hash: 0055c56d412e6ab765048f1b8e7fce3b2553435c765c2899ee1bd3124d056098 Target: 0100000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0001 seconds Hashing Power: 234199 hashes per second Difficulty: 9 bits Nonce: 2 Hash: 0025a3e3e764ad05f7945eb65d2a21445eded2209a2cd0e26fa8571bd886b0da Target: 0080000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0000 seconds Hashing Power: 104857 hashes per second Difficulty: 10 bits Nonce: 1514 Hash: 002a67dc2d861c93843e6dfdb0402f4fed2e87c8c30408f016ac83521e8f091b Target: 0040000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0046 seconds Hashing Power: 330566 hashes per second Difficulty: 11 bits Nonce: 856 Hash: 0014739d631bf69324d51dfa4ebcd28b03d09e6285d76fc9dc8b7c1e8ad1bf47 Target: 0020000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0026 seconds Hashing Power: 329236 hashes per second Difficulty: 12 bits Nonce: 2933 Hash: 00034d0888fb1cc74a4ee823eae4b71d8949e453da89f24caf3088b557f241c2 Target: 0010000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0091 seconds Hashing Power: 321988 hashes per second Difficulty: 13 bits Nonce: 2142 Hash: 00014006170118b30d97b81e4a824357d416866b469dfc56d16db31e5486f5a0 Target: 0008000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0066 seconds Hashing Power: 325090 hashes per second Difficulty: 14 bits Nonce: 8955 Hash: 0003295d9c3908df0275e074cd820af49a3e5975c487014a23fd7ba5fb98635b Target: 0004000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0313 seconds Hashing Power: 286101 hashes per second Difficulty: 15 bits Nonce: 32930 Hash: 00009a09fa6f72af0861650e655cf8901b33cf37614ddc0fcfa230294ee22988 Target: 0002000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.1012 seconds Hashing Power: 325253 hashes per second Difficulty: 16 bits Nonce: 285299 Hash: 00009d85ce6e17b625bc50caafc7a42eab41d108a177cbfce39c4045bee69fd8 Target: 0001000000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.8588 seconds Hashing Power: 332214 hashes per second Difficulty: 17 bits Nonce: 10460 Hash: 000012726c26b999bb05e81322379a9ed9ecf08bd85347c752a913ec5e6942e6 Target: 0000800000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0309 seconds Hashing Power: 338817 hashes per second Difficulty: 18 bits Nonce: 11980 Hash: 000020b111acbfe28ac4e68aa267154b12cb224bbf49f2c56db346f039b21395 Target: 0000400000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.0389 seconds Hashing Power: 307621 hashes per second Difficulty: 19 bits Nonce: 573192 Hash: 00001cce66856179a3feed94420d126a9dbddfa8830fc41b7fc5d36fdbf03ba0 Target: 0000200000000000000000000000000000000000000000000000000000000000 Elapsed Time: 1.7196 seconds Hashing Power: 333336 hashes per second Difficulty: 20 bits Nonce: 237723 Hash: 000005720acd8c7207cbf495e85733f196feb1e3692405bea0ee864104039350 Target: 0000100000000000000000000000000000000000000000000000000000000000 Elapsed Time: 0.7161 seconds Hashing Power: 331977 hashes per second Difficulty: 21 bits Nonce: 687438 Hash: 000003a6eeee97491a9183e4c57458172edb6f9466377bf44afbd74e410f6eef Target: 0000080000000000000000000000000000000000000000000000000000000000 Elapsed Time: 2.0783 seconds Hashing Power: 330763 hashes per second Difficulty: 22 bits Nonce: 1759164 Hash: 0000008bb8f0e731f0496b8e530da984e85fb3cd2bd81882fe8ba3610b6cefc3 Target: 0000040000000000000000000000000000000000000000000000000000000000 Elapsed Time: 5.2847 seconds Hashing Power: 332877 hashes per second Difficulty: 23 bits Nonce: 14214729 Hash: 000001408cf12dbd20fcba6372a223e098d58786c6ff93488a9f74f5df4df0a3 Target: 0000020000000000000000000000000000000000000000000000000000000000 Elapsed Time: 42.8228 seconds Hashing Power: 331942 hashes per second Difficulty: 24 bits Nonce: 24586379 Hash: 0000002c3d6b370fccd699708d1b7cb4a94388595171366b944d68b2acce8b95 Target: 0000010000000000000000000000000000000000000000000000000000000000 Elapsed Time: 73.9447 seconds Hashing Power: 332496 hashes per second Difficulty: 25 bits Nonce: 8570323 Hash: 00000009ecccb8289d6f94b3e861804e41c4530b0f879534597ff4d09aaa446d Target: 0000008000000000000000000000000000000000000000000000000000000000 Elapsed Time: 25.7419 seconds Hashing Power: 332932 hashes per second Difficulty: 26 bits Nonce: 84561291 Hash: 0000001f0ea21e676b6dde5ad429b9d131a9f2b000802ab2f169cbca22b1e21a Target: 0000004000000000000000000000000000000000000000000000000000000000 Elapsed Time: 254.2355 seconds Hashing Power: 332610 hashes per second Difficulty: 27 bits Nonce: 10256713 Hash: 00000006dc70d218bafb37c31f3166e49b1b0d28f3fea500431ecb22e954c99e Target: 0000002000000000000000000000000000000000000000000000000000000000 Elapsed Time: 30.8556 seconds Hashing Power: 332409 hashes per second Difficulty: 28 bits Nonce: 139905000 Hash: 0000000e4da88b53f70b2c5fc142500f0633e6407a4793462c54e6e704a687f3 Target: 0000001000000000000000000000000000000000000000000000000000000000 Elapsed Time: 420.3545 seconds Hashing Power: 332826 hashes per second Difficulty: 29 bits Nonce: 61508685 Hash: 0000000135c4a4e6c78c12e956ea970e5c6b2f586bedcde2cf8507e2b08b87eb Target: 0000000800000000000000000000000000000000000000000000000000000000 Elapsed Time: 184.9352 seconds Hashing Power: 332595 hashes per second Difficulty: 30 bits Nonce: 590689799 Hash: 0000000339323dfd8e68d9460ba4311efa5da8393aa986ff2c00e7f4a54e9761 Target: 0000000400000000000000000000000000000000000000000000000000000000 Elapsed Time: 1950.6458 seconds Hashing Power: 302817 hashes per second |
Targetの数が小さくなると急激にハッシュを見つけ出す時間がかかるようになります。
下記は過去からの実際のBitcoinのハッシュレートと難易度の変化を表したグラフです。
170m TH/sということは、THのmはメガ? 170 EH/s ってすごい計算量ということがわかります。
(上記は、古いPCで約30万/s)
TH/s（テラハッシュ） 1秒間に1,000,000,000,000（1兆）回
PH/s（ペタハッシュ） 1秒間に1,000,000,000,000,000（1000兆）回
EH/s（エクサハッシュ） 1秒間に1,000,000,000,000,000,000（100京）回
https://www.blockchain.com/charts/hash-rate より
https://www.blockchain.com/charts/difficulty より
ハッシュレートと難易度が同じ動きをしていることがわかります。このように動的に計算負荷をコントールしているのですね。
昔は、PCのCPUでマイニングし、次にGPU、そしてFPGAにASICとハードウェアも変遷しているようですが、マイニングがいかにコストがかかるよく表しています。
それにしても何もかもオープンなんだと、あらためて感じました。
ブロックチェーンはBitcoinに限らす社会に影響を大きく与える技術だけに、そのしくみを知りたいという気持ちが強くなってきました。上記参考書籍はとても詳しくわかりやすく書かれており、おすすめです。
今年はブロックチェーンテクノロジーの探求に力を入れていきたいと思います。
専用ブログ開始しました!
http://bitlife.me/bc/
Categories: 未分類 タグ: Blockchain, Python