114 lines
2.7 KiB
C++
114 lines
2.7 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2014 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_RANDOM_H
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#define BITCOIN_RANDOM_H
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#include "uint256.h"
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#include <stdint.h>
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/* Seed OpenSSL PRNG with additional entropy data */
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void RandAddSeed();
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/**
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* Functions to gather random data via the OpenSSL PRNG
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*/
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void GetRandBytes(unsigned char* buf, int num);
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uint64_t GetRand(uint64_t nMax);
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int GetRandInt(int nMax);
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uint256 GetRandHash();
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/**
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* Function to gather random data from multiple sources, failing whenever any
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* of those source fail to provide a result.
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*/
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void GetStrongRandBytes(unsigned char* buf, int num);
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/**
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* Seed insecure_rand using the random pool.
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* @param Deterministic Use a deterministic seed
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*/
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void seed_insecure_rand(bool fDeterministic = false);
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/**
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* Fast randomness source. This is seeded once with secure random data, but
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* is completely deterministic and insecure after that.
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* This class is not thread-safe.
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*/
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class FastRandomContext
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{
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private:
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uint64_t bitbuf;
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int bitbuf_size;
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void FillBitBuffer()
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{
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bitbuf = rand64();
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bitbuf_size = 64;
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}
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public:
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explicit FastRandomContext(bool fDeterministic = false);
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uint32_t Rz;
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uint32_t Rw;
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uint32_t rand32()
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{
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Rz = 36969 * (Rz & 65535) + (Rz >> 16);
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Rw = 18000 * (Rw & 65535) + (Rw >> 16);
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return (Rw << 16) + Rz;
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}
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uint64_t rand64()
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{
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uint64_t a = rand32();
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uint64_t b = rand32();
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return (b << 32) + a;
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}
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bool randbool() { return rand32() & 1; }
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uint64_t randbits(int bits)
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{
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if (bits == 0)
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{
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return 0;
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}
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else if (bits > 32)
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{
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return rand64() >> (64 - bits);
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}
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else
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{
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if (bitbuf_size < bits)
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FillBitBuffer();
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uint64_t ret = bitbuf & (~uint64_t(0) >> (64 - bits));
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bitbuf >>= bits;
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bitbuf_size -= bits;
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return ret;
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}
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}
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};
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/**
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* MWC RNG of George Marsaglia
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* This is intended to be fast. It has a period of 2^59.3, though the
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* least significant 16 bits only have a period of about 2^30.1.
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*
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* @return random value
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*/
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extern uint32_t insecure_rand_Rz;
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extern uint32_t insecure_rand_Rw;
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static inline uint32_t insecure_rand(void)
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{
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insecure_rand_Rz = 36969 * (insecure_rand_Rz & 65535) + (insecure_rand_Rz >> 16);
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insecure_rand_Rw = 18000 * (insecure_rand_Rw & 65535) + (insecure_rand_Rw >> 16);
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return (insecure_rand_Rw << 16) + insecure_rand_Rz;
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}
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#endif // BITCOIN_RANDOM_H
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