git / moonbite-core / src/compressor.cpp · raw
// Copyright (c) 2009-2010 Satoshi Nakamoto// Copyright (c) 2009-2019 The Bitcoin Core developers// Distributed under the MIT software license, see the accompanying// file COPYING or http://www.opensource.org/licenses/mit-license.php.#include <compressor.h>#include <pubkey.h>#include <script/standard.h>/* * These check for scripts for which a special case with a shorter encoding is defined. * They are implemented separately from the CScript test, as these test for exact byte * sequence correspondences, and are more strict. For example, IsToPubKey also verifies * whether the public key is valid (as invalid ones cannot be represented in compressed * form). */static bool IsToKeyID(const CScript& script, CKeyID &hash){ if (script.size() == 25 && script[0] == OP_DUP && script[1] == OP_HASH160 && script[2] == 20 && script[23] == OP_EQUALVERIFY && script[24] == OP_CHECKSIG) { memcpy(&hash, &script[3], 20); return true; } return false;}static bool IsToScriptID(const CScript& script, CScriptID &hash){ if (script.size() == 23 && script[0] == OP_HASH160 && script[1] == 20 && script[22] == OP_EQUAL) { memcpy(&hash, &script[2], 20); return true; } return false;}static bool IsToPubKey(const CScript& script, CPubKey &pubkey){ if (script.size() == 35 && script[0] == 33 && script[34] == OP_CHECKSIG && (script[1] == 0x02 || script[1] == 0x03)) { pubkey.Set(&script[1], &script[34]); return true; } if (script.size() == 67 && script[0] == 65 && script[66] == OP_CHECKSIG && script[1] == 0x04) { pubkey.Set(&script[1], &script[66]); return pubkey.IsFullyValid(); // if not fully valid, a case that would not be compressible } return false;}bool CompressScript(const CScript& script, std::vector<unsigned char> &out){ CKeyID keyID; if (IsToKeyID(script, keyID)) { out.resize(21); out[0] = 0x00; memcpy(&out[1], &keyID, 20); return true; } CScriptID scriptID; if (IsToScriptID(script, scriptID)) { out.resize(21); out[0] = 0x01; memcpy(&out[1], &scriptID, 20); return true; } CPubKey pubkey; if (IsToPubKey(script, pubkey)) { out.resize(33); memcpy(&out[1], &pubkey[1], 32); if (pubkey[0] == 0x02 || pubkey[0] == 0x03) { out[0] = pubkey[0]; return true; } else if (pubkey[0] == 0x04) { out[0] = 0x04 | (pubkey[64] & 0x01); return true; } } return false;}unsigned int GetSpecialScriptSize(unsigned int nSize){ if (nSize == 0 || nSize == 1) return 20; if (nSize == 2 || nSize == 3 || nSize == 4 || nSize == 5) return 32; return 0;}bool DecompressScript(CScript& script, unsigned int nSize, const std::vector<unsigned char> &in){ switch(nSize) { case 0x00: script.resize(25); script[0] = OP_DUP; script[1] = OP_HASH160; script[2] = 20; memcpy(&script[3], in.data(), 20); script[23] = OP_EQUALVERIFY; script[24] = OP_CHECKSIG; return true; case 0x01: script.resize(23); script[0] = OP_HASH160; script[1] = 20; memcpy(&script[2], in.data(), 20); script[22] = OP_EQUAL; return true; case 0x02: case 0x03: script.resize(35); script[0] = 33; script[1] = nSize; memcpy(&script[2], in.data(), 32); script[34] = OP_CHECKSIG; return true; case 0x04: case 0x05: unsigned char vch[33] = {}; vch[0] = nSize - 2; memcpy(&vch[1], in.data(), 32); CPubKey pubkey(&vch[0], &vch[33]); if (!pubkey.Decompress()) return false; assert(pubkey.size() == 65); script.resize(67); script[0] = 65; memcpy(&script[1], pubkey.begin(), 65); script[66] = OP_CHECKSIG; return true; } return false;}// Amount compression:// * If the amount is 0, output 0// * first, divide the amount (in base units) by the largest power of 10 possible; call the exponent e (e is max 9)// * if e<9, the last digit of the resulting number cannot be 0; store it as d, and drop it (divide by 10)// * call the result n// * output 1 + 10*(9*n + d - 1) + e// * if e==9, we only know the resulting number is not zero, so output 1 + 10*(n - 1) + 9// (this is decodable, as d is in [1-9] and e is in [0-9])uint64_t CompressAmount(uint64_t n){ if (n == 0) return 0; int e = 0; while (((n % 10) == 0) && e < 9) { n /= 10; e++; } if (e < 9) { int d = (n % 10); assert(d >= 1 && d <= 9); n /= 10; return 1 + (n*9 + d - 1)*10 + e; } else { return 1 + (n - 1)*10 + 9; }}uint64_t DecompressAmount(uint64_t x){ // x = 0 OR x = 1+10*(9*n + d - 1) + e OR x = 1+10*(n - 1) + 9 if (x == 0) return 0; x--; // x = 10*(9*n + d - 1) + e int e = x % 10; x /= 10; uint64_t n = 0; if (e < 9) { // x = 9*n + d - 1 int d = (x % 9) + 1; x /= 9; // x = n n = x*10 + d; } else { n = x+1; } while (e) { n *= 10; e--; } return n;}