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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,209 @@ | ||
| // | ||
| // ChaCha.swift | ||
| // RandomKit | ||
| // | ||
| // The MIT License (MIT) | ||
| // | ||
| // Copyright (c) 2015-2017 Nikolai Vazquez | ||
| // | ||
| // Permission is hereby granted, free of charge, to any person obtaining a copy | ||
| // of this software and associated documentation files (the "Software"), to deal | ||
| // in the Software without restriction, including without limitation the rights | ||
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | ||
| // copies of the Software, and to permit persons to whom the Software is | ||
| // furnished to do so, subject to the following conditions: | ||
| // | ||
| // The above copyright notice and this permission notice shall be included in | ||
| // all copies or substantial portions of the Software. | ||
| // | ||
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | ||
| // THE SOFTWARE. | ||
| // | ||
|
|
||
| /// A generator that uses a [ChaCha20][1] algorithm. | ||
| /// | ||
| /// This implementation is taken from that of [ChaCha][2] in the Rust `rand` crate. | ||
| /// | ||
| /// [1]: http://cr.yp.to/chacha.html | ||
| /// [2]: https://doc.rust-lang.org/rand/rand/chacha/struct.ChaChaRng.html | ||
| public struct ChaCha: RandomBytesGenerator, SeedableFromOtherRandomGenerator { | ||
|
|
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| private typealias _State = _Array16<UInt32> | ||
|
|
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| private static let _stateCount = 16 | ||
|
|
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| private static let _keyCount = 8 | ||
|
|
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| private static let _rounds = 20 | ||
|
|
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| private static var _empty: ChaCha { | ||
| return ChaCha(_buffer: _zero16(), _state: _zero16(), _index: _stateCount) | ||
| } | ||
|
|
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| /// A default global instance seeded with `DeviceRandom.default`. | ||
| public static var `default` = seeded | ||
|
|
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| /// A default global instance that reseeds itself with `DeviceRandom.default`. | ||
| public static var defaultReseeding = reseeding | ||
|
|
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| /// Returns an unseeded instance. | ||
| public static var unseeded: ChaCha { | ||
| var result = _empty | ||
| result._reset() | ||
| return result | ||
| } | ||
|
|
||
| private var _buffer: _State | ||
|
|
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| private var _state: _State | ||
|
|
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| private var _index: Int | ||
|
|
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| private var _bufferPointer: UnsafeMutablePointer<UInt32> { | ||
| mutating get { return _pointer(to: &_buffer) } | ||
| } | ||
|
|
||
| private var _statePointer: UnsafeMutablePointer<UInt32> { | ||
| mutating get { return _pointer(to: &_state) } | ||
| } | ||
|
|
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| private init(_buffer: _State, _state: _State, _index: Int) { | ||
| self._buffer = _buffer | ||
| self._state = _state | ||
| self._index = _index | ||
| } | ||
|
|
||
| /// Creates an instance from `seed`. | ||
| public init(seed: UnsafeBufferPointer<UInt32>) { | ||
| self = ._empty | ||
| reseed(with: seed) | ||
| } | ||
|
|
||
| /// Creates an instance from `seed`. | ||
| public init<S: Sequence>(seed: S) where S.Iterator.Element == UInt32 { | ||
| self = ._empty | ||
| reseed(with: seed) | ||
| } | ||
|
|
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| /// Creates an instance seeded with `randomGenerator`. | ||
| public init<R: RandomGenerator>(seededWith randomGenerator: inout R) { | ||
| var seed: _Array8<UInt32> = randomGenerator.randomUnsafeValue() | ||
| let pointer = _pointer(to: &seed, as: UInt32.self) | ||
| let buffer = UnsafeBufferPointer(start: pointer, count: ChaCha._keyCount) | ||
| self.init(seed: buffer) | ||
| } | ||
|
|
||
| private mutating func _reset() { | ||
| _initialize(from: _zero8()) | ||
| } | ||
|
|
||
| private mutating func _initialize(from key: _Array8<UInt32>) { | ||
| _state.0 = 0x61707865 | ||
| _state.1 = 0x3320646E | ||
| _state.2 = 0x79622D32 | ||
| _state.3 = 0x6B206574 | ||
| _state.4 = key.0 | ||
| _state.5 = key.1 | ||
| _state.6 = key.2 | ||
| _state.7 = key.3 | ||
| _state.8 = key.4 | ||
| _state.9 = key.5 | ||
| _state.10 = key.6 | ||
| _state.11 = key.7 | ||
| _state.12 = 0 | ||
| _state.13 = 0 | ||
| _state.14 = 0 | ||
| _state.15 = 0 | ||
| } | ||
|
|
||
| private mutating func _update() { | ||
| let bufferPtr = _bufferPointer | ||
| let statePtr = _statePointer | ||
| _buffer = _state | ||
| _index = 0 | ||
| for _ in 0 ..< ChaCha._rounds / 2 { | ||
| _doubleRound(bufferPtr) | ||
| } | ||
| for i in 0 ..< ChaCha._stateCount { | ||
| bufferPtr[i] = bufferPtr[i] &+ statePtr[i] | ||
| } | ||
| for i in 12 ..< 16 { | ||
| statePtr[i] = statePtr[i] &+ 1 | ||
| guard statePtr[i] == 0 else { | ||
| return | ||
| } | ||
| } | ||
| } | ||
|
|
||
| private mutating func _reseed<S: Sequence>(with seed: S) where S.Iterator.Element == UInt32 { | ||
| reseed(with: seed) | ||
| } | ||
|
|
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| /// Sets the internal 128-bit counter. | ||
| public mutating func setCounter(low: UInt64, high: UInt64) { | ||
| _state.12 = UInt32(truncatingBitPattern: low) | ||
| _state.13 = UInt32(truncatingBitPattern: low >> 32) | ||
| _state.14 = UInt32(truncatingBitPattern: high) | ||
| _state.15 = UInt32(truncatingBitPattern: high >> 32) | ||
| _index = ChaCha._stateCount | ||
| } | ||
|
|
||
| /// Reseeds `self` with `seed`. | ||
| public mutating func reseed(with seed: UnsafeBufferPointer<UInt32>) { | ||
| // Required to specify method with same name. | ||
| _reseed(with: seed) | ||
| } | ||
|
|
||
| /// Reseeds `self` with `seed`. | ||
| public mutating func reseed<S: Sequence>(with seed: S) where S.Iterator.Element == UInt32 { | ||
| _reset() | ||
| let keyPointer = _statePointer | ||
| for (i, s) in zip(4 ..< ChaCha._keyCount + 4, seed) { | ||
| keyPointer[i] = s | ||
| } | ||
| } | ||
|
|
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| /// Returns random `Bytes`. | ||
| public mutating func randomBytes() -> UInt32 { | ||
| if _index == ChaCha._stateCount { | ||
| _update() | ||
| } | ||
| defer { _index += 1 } | ||
| return _bufferPointer[_index % ChaCha._stateCount] | ||
| } | ||
|
|
||
| } | ||
|
|
||
| extension UInt32 { | ||
| @inline(__always) | ||
| fileprivate func _rotateLeft(_ n: UInt32) -> UInt32 { | ||
| return (self << n) | (self >> (32 &- n)) | ||
| } | ||
| } | ||
|
|
||
| @inline(__always) | ||
| private func _quarterRound(_ a: inout UInt32, _ b: inout UInt32, _ c: inout UInt32, _ d: inout UInt32) { | ||
| a = a &+ b; d ^= a; d = d._rotateLeft(16) | ||
| c = c &+ d; b ^= c; b = b._rotateLeft(12) | ||
| a = a &+ b; d ^= a; d = d._rotateLeft(8) | ||
| c = c &+ d; b ^= c; b = b._rotateLeft(7) | ||
| } | ||
|
|
||
| @inline(__always) | ||
| private func _doubleRound(_ x: UnsafeMutablePointer<UInt32>) { | ||
| // Column round | ||
| _quarterRound(&x[0], &x[4], &x[8], &x[12]) | ||
| _quarterRound(&x[1], &x[5], &x[9], &x[13]) | ||
| _quarterRound(&x[2], &x[6], &x[10], &x[14]) | ||
| _quarterRound(&x[3], &x[7], &x[11], &x[15]) | ||
| // Diagonal round | ||
| _quarterRound(&x[0], &x[5], &x[10], &x[15]) | ||
| _quarterRound(&x[1], &x[6], &x[11], &x[12]) | ||
| _quarterRound(&x[2], &x[7], &x[8], &x[13]) | ||
| _quarterRound(&x[3], &x[4], &x[9], &x[14]) | ||
| } |
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