1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157

// Rust Bitcoin Library
// Written in 2014 by
//   Andrew Poelstra <apoelstra@wpsoftware.net>
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software.
// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
//

//! Consensus parameters
//!
//! This module provides predefined set of parameters for different chains.
//!

use network::constants::Network;
use util::uint::Uint256;

/// Lowest possible difficulty for Mainnet. See comment on Params::pow_limit for more info.
const MAX_BITS_BITCOIN: Uint256 = Uint256([
    0x0000000000000000u64,
    0x0000000000000000u64,
    0x0000000000000000u64,
    0x00000000ffff0000u64,
]);
/// Lowest possible difficulty for Testnet. See comment on Params::pow_limit for more info.
const MAX_BITS_TESTNET: Uint256 = Uint256([
    0x0000000000000000u64,
    0x0000000000000000u64,
    0x0000000000000000u64,
    0x00000000ffff0000u64,
]);
/// Lowest possible difficulty for Signet. See comment on Params::pow_limit for more info.
const MAX_BITS_SIGNET: Uint256 = Uint256([
    0x0000000000000000u64,
    0x0000000000000000u64,
    0x0000000000000000u64,
    0x00000377ae000000u64,
]);
/// Lowest possible difficulty for Regtest. See comment on Params::pow_limit for more info.
const MAX_BITS_REGTEST: Uint256 = Uint256([
    0x0000000000000000u64,
    0x0000000000000000u64,
    0x0000000000000000u64,
    0x7fffff0000000000u64,
]);

#[derive(Debug, Clone)]
/// Parameters that influence chain consensus.
pub struct Params {
    /// Network for which parameters are valid.
    pub network: Network,
    /// Time when BIP16 becomes active.
    pub bip16_time: u32,
    /// Block height at which BIP34 becomes active.
    pub bip34_height: u32,
    /// Block height at which BIP65 becomes active.
    pub bip65_height: u32,
    /// Block height at which BIP66 becomes active.
    pub bip66_height: u32,
    /// Minimum blocks including miner confirmation of the total of 2016 blocks in a retargeting period,
    /// (nPowTargetTimespan / nPowTargetSpacing) which is also used for BIP9 deployments.
    /// Examples: 1916 for 95%, 1512 for testchains.
    pub rule_change_activation_threshold: u32,
    /// Number of blocks with the same set of rules.
    pub miner_confirmation_window: u32,
    /// Proof of work limit value. It contains the lowest possible difficulty.
    ///
    /// Note that this value differs from Bitcoin Core's powLimit field in that this value is
    /// attainable, but Bitcoin Core's is not. Specifically, because targets in Bitcoin are always
    /// rounded to the nearest float expressible in "compact form", not all targets are attainable.
    /// Still, this should not affect consensus as the only place where the non-compact form of
    /// this is used in Bitcoin Core's consensus algorithm is in comparison and there are no
    /// compact-expressible values between Bitcoin Core's and the limit expressed here.
    pub pow_limit: Uint256,
    /// Expected amount of time to mine one block.
    pub pow_target_spacing: u64,
    /// Difficulty recalculation interval.
    pub pow_target_timespan: u64,
    /// Determines whether minimal difficulty may be used for blocks or not.
    pub allow_min_difficulty_blocks: bool,
    /// Determines whether retargeting is disabled for this network or not.
    pub no_pow_retargeting: bool,
}

impl Params {
    /// Creates parameters set for the given network.
    pub fn new(network: Network) -> Self {
        match network {
            Network::Bitcoin => Params {
                network: Network::Bitcoin,
                bip16_time: 1333238400,                 // Apr 1 2012
                bip34_height: 227931, // 000000000000024b89b42a942fe0d9fea3bb44ab7bd1b19115dd6a759c0808b8
                bip65_height: 388381, // 000000000000000004c2b624ed5d7756c508d90fd0da2c7c679febfa6c4735f0
                bip66_height: 363725, // 00000000000000000379eaa19dce8c9b722d46ae6a57c2f1a988119488b50931
                rule_change_activation_threshold: 1916, // 95%
                miner_confirmation_window: 2016,
                pow_limit: MAX_BITS_BITCOIN,
                pow_target_spacing: 10 * 60,            // 10 minutes.
                pow_target_timespan: 14 * 24 * 60 * 60, // 2 weeks.
                allow_min_difficulty_blocks: false,
                no_pow_retargeting: false,
            },
            Network::Testnet => Params {
                network: Network::Testnet,
                bip16_time: 1333238400,                 // Apr 1 2012
                bip34_height: 21111, // 0000000023b3a96d3484e5abb3755c413e7d41500f8e2a5c3f0dd01299cd8ef8
                bip65_height: 581885, // 00000000007f6655f22f98e72ed80d8b06dc761d5da09df0fa1dc4be4f861eb6
                bip66_height: 330776, // 000000002104c8c45e99a8853285a3b592602a3ccde2b832481da85e9e4ba182
                rule_change_activation_threshold: 1512, // 75%
                miner_confirmation_window: 2016,
                pow_limit: MAX_BITS_TESTNET,
                pow_target_spacing: 10 * 60,            // 10 minutes.
                pow_target_timespan: 14 * 24 * 60 * 60, // 2 weeks.
                allow_min_difficulty_blocks: true,
                no_pow_retargeting: false,
            },
            Network::Signet => Params {
                network: Network::Signet,
                bip16_time: 1333238400,                 // Apr 1 2012
                bip34_height: 1,
                bip65_height: 1,
                bip66_height: 1,
                rule_change_activation_threshold: 1916, // 95%
                miner_confirmation_window: 2016,
                pow_limit: MAX_BITS_SIGNET,
                pow_target_spacing: 10 * 60,            // 10 minutes.
                pow_target_timespan: 14 * 24 * 60 * 60, // 2 weeks.
                allow_min_difficulty_blocks: false,
                no_pow_retargeting: false,
            },
            Network::Regtest => Params {
                network: Network::Regtest,
                bip16_time: 1333238400,  // Apr 1 2012
                bip34_height: 100000000, // not activated on regtest
                bip65_height: 1351,
                bip66_height: 1251,                    // used only in rpc tests
                rule_change_activation_threshold: 108, // 75%
                miner_confirmation_window: 144,
                pow_limit: MAX_BITS_REGTEST,
                pow_target_spacing: 10 * 60,            // 10 minutes.
                pow_target_timespan: 14 * 24 * 60 * 60, // 2 weeks.
                allow_min_difficulty_blocks: true,
                no_pow_retargeting: true,
            },
        }
    }

    /// Calculates the number of blocks between difficulty adjustments.
    pub fn difficulty_adjustment_interval(&self) -> u64 {
        self.pow_target_timespan / self.pow_target_spacing
    }
}