85 lines
3.2 KiB
Go
85 lines
3.2 KiB
Go
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// Copyright 2017-2021 DERO Project. All rights reserved.
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// Use of this source code in any form is governed by RESEARCH license.
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// license can be found in the LICENSE file.
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// GPG: 0F39 E425 8C65 3947 702A 8234 08B2 0360 A03A 9DE8
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//
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package main
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// ripoff from blockchain folder
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import "math/big"
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import "github.com/deroproject/derohe/cryptography/crypto"
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var (
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// bigZero is 0 represented as a big.Int. It is defined here to avoid
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// the overhead of creating it multiple times.
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bigZero = big.NewInt(0)
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// bigOne is 1 represented as a big.Int. It is defined here to avoid
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// the overhead of creating it multiple times.
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bigOne = big.NewInt(1)
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// oneLsh256 is 1 shifted left 256 bits. It is defined here to avoid
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// the overhead of creating it multiple times.
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oneLsh256 = new(big.Int).Lsh(bigOne, 256)
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// enabling this will simulation mode with hard coded difficulty set to 1
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// the variable is knowingly not exported, so no one can tinker with it
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//simulation = false // simulation mode is disabled
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)
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// HashToBig converts a PoW has into a big.Int that can be used to
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// perform math comparisons.
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func HashToBig(buf crypto.Hash) *big.Int {
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// A Hash is in little-endian, but the big package wants the bytes in
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// big-endian, so reverse them.
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blen := len(buf) // its hardcoded 32 bytes, so why do len but lets do it
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for i := 0; i < blen/2; i++ {
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buf[i], buf[blen-1-i] = buf[blen-1-i], buf[i]
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}
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return new(big.Int).SetBytes(buf[:])
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}
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// this function calculates the difficulty in big num form
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func ConvertDifficultyToBig(difficultyi uint64) *big.Int {
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if difficultyi == 0 {
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panic("difficulty can never be zero")
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}
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// (1 << 256) / (difficultyNum )
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difficulty := new(big.Int).SetUint64(difficultyi)
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denominator := new(big.Int).Add(difficulty, bigZero) // above 2 lines can be merged
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return new(big.Int).Div(oneLsh256, denominator)
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}
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func ConvertIntegerDifficultyToBig(difficultyi *big.Int) *big.Int {
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if difficultyi.Cmp(bigZero) == 0 { // if work_pow is less than difficulty
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panic("difficulty can never be zero")
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}
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return new(big.Int).Div(oneLsh256, difficultyi)
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}
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// this function check whether the pow hash meets difficulty criteria
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// however, it take diff in bigint format
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func CheckPowHashBig(pow_hash crypto.Hash, big_difficulty_integer *big.Int) bool {
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big_pow_hash := HashToBig(pow_hash)
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big_difficulty := ConvertIntegerDifficultyToBig(big_difficulty_integer)
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if big_pow_hash.Cmp(big_difficulty) <= 0 { // if work_pow is less than difficulty
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return true
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}
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return false
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}
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