PacketCrypt/src/Difficulty.c at develop · javascriptit/PacketCrypt · GitHub

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/**

* Caleb James DeLisle

* SPDX-License-Identifier: (LGPL-2.1-only OR LGPL-3.0-only)

#include "Difficulty.h"

#include "Conf.h"

#include "config.h"

#include <assert.h>

#include <stdbool.h>

#ifdef __APPLE__

// Apple ships with openssl and then complains when you use it

// because they'd rather you use their framework instead

#pragma GCC diagnostic ignored "-Wdeprecated-declarations"

#endif

#include <openssl/bn.h>

static void bnSetCompact(BIGNUM* bn, uint32_t nCompact)

{

unsigned int nSize = nCompact >> 24;

bool fNegative =(nCompact & 0x00800000) != 0;

unsigned int nWord = nCompact & 0x007fffff;

if (nSize <= 3)

{

nWord >>= 8*(3-nSize);

assert(BN_set_word(bn, nWord));

}

else

{

assert(BN_set_word(bn, nWord));

assert(BN_lshift(bn, bn, 8*(nSize-3)));

}

BN_set_negative(bn, fNegative);

}

static uint32_t bnGetCompact(const BIGNUM* bn)

{

unsigned int nSize = BN_num_bytes(bn);

unsigned int nCompact = 0;

if (nSize <= 3)

nCompact = BN_get_word(bn) << 8*(3-nSize);

else

{

//CBigNum x;

BIGNUM* x = BN_new();

assert(x);

assert(BN_rshift(x, bn, 8*(nSize-3)));

nCompact = BN_get_word(x);

BN_free(x);

}

// The 0x00800000 bit denotes the sign.

// Thus, if it is already set, divide the mantissa by 256 and increase the exponent.

if (nCompact & 0x00800000)

{

nCompact >>= 8;

nSize++;

}

nCompact |= nSize << 24;

nCompact |= (BN_is_negative(bn) ? 0x00800000 : 0);

return nCompact;

}

static inline void bn256(BIGNUM* out) {

BN_one(out);

assert(BN_lshift(out, out, 256));

}

// work = 2**256 / (target + 1)

static inline void bnWorkForDiff(BN_CTX* ctx, BIGNUM* workOut, /*const*/ BIGNUM* diff) {

// workOut = 2**256

bn256(workOut);

// diff++

assert(BN_add(diff, diff, BN_value_one()));

// workOut /= diff

assert(BN_div(workOut, NULL, workOut, diff, ctx));

// diff--

assert(BN_sub(diff, diff, BN_value_one()));

}

// diffOut = (2**256 - work) / work

static inline void bnDiffForWork(BN_CTX* ctx, BIGNUM* diffOut, const BIGNUM* work)

{

// diffOut = 2**256

bn256(diffOut);

// if work is zero then target is maximum (minimum difficulty)

if (BN_is_zero(work)) { return; }

// diffOut -= work

assert(BN_sub(diffOut, diffOut, work));

// diffOut /= work

assert(BN_div(diffOut, NULL, diffOut, work, ctx));

}

static void setuint64(BIGNUM* out, uint64_t n)

{

unsigned char pch[sizeof(n) + 6];

unsigned char* p = pch + 4;

bool fLeadingZeroes = true;

for (int i = 0; i < 8; i++)

{

unsigned char c = (n >> 56) & 0xff;

n <<= 8;

if (fLeadingZeroes)

{

if (c == 0)

continue;

if (c & 0x80)

*p++ = 0;

fLeadingZeroes = false;

}

*p++ = c;

}

unsigned int nSize = p - (pch + 4);

pch[0] = (nSize >> 24) & 0xff;

pch[1] = (nSize >> 16) & 0xff;

pch[2] = (nSize >> 8) & 0xff;

pch[3] = (nSize) & 0xff;

assert(BN_mpi2bn(pch, p - pch, out) == out);

}

static inline void assign(BIGNUM* out, const BIGNUM* val) {

assert(BN_zero(out));

assert(BN_add(out, out, val));

}

static inline void getEffectiveWork(

BN_CTX* ctx,

BIGNUM* workOut,

const BIGNUM* blockWork,

const BIGNUM* annWork,

uint64_t annCount)

{

if (BN_is_zero(annWork) || !annCount) {

// This is work *required* so when there is no work and no announcements

// that work is "infinite".

bn256(workOut);

return;

}

assign(workOut, blockWork);

// workOut = workOut**3

assert(BN_sqr(workOut, workOut, ctx));

assert(BN_mul(workOut, workOut, blockWork, ctx));

#ifdef PCP2

// difficulty *= 1024

assert(BN_lshift(workOut, workOut, 10));

#endif

// workOut /= annWork

assert(BN_div(workOut, NULL, workOut, annWork, ctx));

BIGNUM* bnAnnCount = BN_new();

assert(bnAnnCount);

setuint64(bnAnnCount, annCount);

#ifdef PCP2

assert(BN_sqr(bnAnnCount, bnAnnCount, ctx));

#endif

// workOut /= annCount

assert(BN_div(workOut, NULL, workOut, bnAnnCount, ctx));

BN_free(bnAnnCount);

}

uint32_t Difficulty_getEffectiveTarget(uint32_t blockTar, uint32_t annTar, uint64_t annCount)

{

BN_CTX* ctx = BN_CTX_new();

assert(ctx);

BIGNUM* x = BN_new(); assert(x);

BIGNUM* bnBlockWork = BN_new(); assert(bnBlockWork);

BIGNUM* bnAnnWork = BN_new(); assert(bnAnnWork);

bnSetCompact(x, blockTar);

bnWorkForDiff(ctx, bnBlockWork, x);

bnSetCompact(x, annTar);

bnWorkForDiff(ctx, bnAnnWork, x);

getEffectiveWork(ctx, x, bnBlockWork, bnAnnWork, annCount);

bnDiffForWork(ctx, bnBlockWork, x);

uint32_t res = bnGetCompact(bnBlockWork);

BN_free(x);

BN_free(bnBlockWork);

BN_free(bnAnnWork);

BN_CTX_free(ctx);

return res > 0x207fffff ? 0x207fffff : res;

}

uint64_t Difficulty_getHashRateMultiplier(uint32_t annTar, uint64_t annCount)

{

BN_CTX* ctx = BN_CTX_new();

assert(ctx);

BIGNUM* x = BN_new(); assert(x);

BIGNUM* bnAnnWork = BN_new(); assert(bnAnnWork);

BIGNUM* bnAnnCount = BN_new(); assert(bnAnnCount);

bnSetCompact(x, annTar);

bnWorkForDiff(ctx, bnAnnWork, x);

setuint64(bnAnnCount, annCount);

#ifdef PCP2

assert(BN_sqr(bnAnnCount, bnAnnCount, ctx));

#endif

assert(BN_mul(x, bnAnnWork, bnAnnCount, ctx));

#ifdef PCP2

// Difficulty jumps by 1024

assert(BN_rshift(x, x, 10));

#endif

uint64_t out = BN_get_word(x);

BN_free(bnAnnCount);

BN_free(bnAnnWork);

BN_free(x);

BN_CTX_free(ctx);

return out;

}

static inline uint32_t degradeAnnouncementTarget2(uint32_t annTar, uint32_t annAgeBlocks)

{

if (annAgeBlocks < Conf_PacketCrypt_ANN_WAIT_PERIOD) { return 0xffffffff; }

if (annAgeBlocks == Conf_PacketCrypt_ANN_WAIT_PERIOD) { return annTar; }

annAgeBlocks -= Conf_PacketCrypt_ANN_WAIT_PERIOD;

BIGNUM* bnAnnTar = BN_new(); assert(bnAnnTar);

bnSetCompact(bnAnnTar, annTar);

assert(BN_lshift(bnAnnTar, bnAnnTar, annAgeBlocks));

uint32_t out = 0xffffffff;

if (BN_num_bits(bnAnnTar) < 256) {

out = bnGetCompact(bnAnnTar);

}

BN_free(bnAnnTar);

return out > 0x207fffff ? 0xffffffff : out;

}

uint32_t Difficulty_degradeAnnouncementTarget(uint32_t annTar, uint32_t annAgeBlocks)

{

#ifdef PCP2

return degradeAnnouncementTarget2(annTar, annAgeBlocks);

#endif

if (annAgeBlocks < Conf_PacketCrypt_ANN_WAIT_PERIOD) { return 0xffffffff; }

annAgeBlocks -= (Conf_PacketCrypt_ANN_WAIT_PERIOD - 1);

BN_CTX* ctx = BN_CTX_new(); assert(ctx);

BIGNUM* bnAnnTar = BN_new(); assert(bnAnnTar);

BIGNUM* bnAnnWork = BN_new(); assert(bnAnnWork);

BIGNUM* bnAnnAgeBlocks = BN_new(); assert(bnAnnAgeBlocks);

setuint64(bnAnnAgeBlocks, annAgeBlocks);

bnSetCompact(bnAnnTar, annTar);

bnWorkForDiff(ctx, bnAnnWork, bnAnnTar);

assert(BN_div(bnAnnWork, NULL, bnAnnWork, bnAnnAgeBlocks, ctx));

bnDiffForWork(ctx, bnAnnTar, bnAnnWork);

uint32_t out = bnGetCompact(bnAnnTar);

BN_free(bnAnnTar);

BN_free(bnAnnWork);

BN_free(bnAnnAgeBlocks);

BN_CTX_free(ctx);

// if out > 0x207fffff then it rounds to zero, meaning the announcement cannot be mined

return out > 0x207fffff ? 0xffffffff : out;

}

// IsAnnMinDiffOk is kind of a sanity check to make sure that the miner doesn't provide

// "silly" results which might trigger wrong behavior from the diff computation

bool Difficulty_isMinAnnDiffOk(uint32_t target)

{

if (target == 0 || target > 0x20ffffff) {

return false;

}

#ifdef PCP2

if (target > 0x207fffff) { return false; }

#endif

BN_CTX* ctx = BN_CTX_new(); assert(ctx);

BIGNUM* bnTar = BN_new(); assert(bnTar);

BIGNUM* bnWork = BN_new(); assert(bnWork);

BIGNUM* bnMax = BN_new(); assert(bnMax);

bnSetCompact(bnTar, target);

#ifdef PCP2

if (BN_is_zero(bnTar) || BN_is_negative(bnTar)) { return false; }

#endif

bnWorkForDiff(ctx, bnWork, bnTar);

if (BN_is_zero(bnWork)) { return false; }

bn256(bnMax);

if (BN_cmp(bnWork, bnMax) >= 0) { return false; }

BN_free(bnTar);

BN_free(bnWork);

BN_free(bnMax);

BN_CTX_free(ctx);

return true;

}

PacketCrypt/src/Difficulty.c at develop · javascriptit/PacketCrypt · GitHub

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