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70 lines
2.9 KiB
70 lines
2.9 KiB
// Copyright (c) 2020, The Monero Project |
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// |
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// All rights reserved. |
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// |
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// Redistribution and use in source and binary forms, with or without modification, are |
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// permitted provided that the following conditions are met: |
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// |
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// 1. Redistributions of source code must retain the above copyright notice, this list of |
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// conditions and the following disclaimer. |
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// |
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list |
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// of conditions and the following disclaimer in the documentation and/or other |
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// materials provided with the distribution. |
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// |
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// 3. Neither the name of the copyright holder nor the names of its contributors may be |
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// used to endorse or promote products derived from this software without specific |
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// prior written permission. |
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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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#pragma once |
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#include <chrono> |
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#include "crypto/crypto.h" |
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namespace crypto |
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{ |
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//! Generate poisson distributed values in discrete `D` time units. |
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template<typename D> |
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struct random_poisson_duration |
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{ |
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using result_type = D; //!< std::chrono::duration time unit precision |
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using rep = typename result_type::rep; //!< Type used to represent duration value |
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//! \param average for generated durations |
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explicit random_poisson_duration(result_type average) |
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: dist(average.count() < 0 ? 0 : average.count()) |
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{} |
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//! Generate a crypto-secure random duration |
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result_type operator()() |
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{ |
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crypto::random_device rand{}; |
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return result_type{dist(rand)}; |
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} |
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private: |
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std::poisson_distribution<rep> dist; |
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}; |
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/* A custom duration is used for subsecond precision because of the |
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variance. If 5000 milliseconds is given, 95% of the values fall between |
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4859ms-5141ms in 1ms increments (not enough time variance). Providing 1/4 |
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seconds would yield 95% of the values between 3s-7.25s in 1/4s |
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increments. */ |
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//! Generate random durations with 1 second precision |
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using random_poisson_seconds = random_poisson_duration<std::chrono::seconds>; |
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//! Generate random duration with 1/4 second precision |
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using random_poisson_subseconds = |
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random_poisson_duration<std::chrono::duration<std::chrono::milliseconds::rep, std::ratio<1, 4>>>; |
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}
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