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// SPDX-License-Identifier: MIT
// Copyright (c) 2015-2021 Zig Contributors
// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
// The MIT license requires this copyright notice to be included in all copies
// and substantial portions of the software.
//! CSPRNG
const std = @import("std");
const Random = std.rand.Random;
const mem = std.mem;
const Gimli = @This();
random: Random,
state: std.crypto.core.Gimli,
pub const secret_seed_length = 32;
/// The seed must be uniform, secret and `secret_seed_length` bytes long.
pub fn init(secret_seed: [secret_seed_length]u8) Gimli {
var initial_state: [std.crypto.core.Gimli.BLOCKBYTES]u8 = undefined;
mem.copy(u8, initial_state[0..secret_seed_length], &secret_seed);
mem.set(u8, initial_state[secret_seed_length..], 0);
var self = Gimli{
.random = Random{ .fillFn = fill },
.state = std.crypto.core.Gimli.init(initial_state),
};
return self;
}
fn fill(r: *Random, buf: []u8) void {
const self = @fieldParentPtr(Gimli, "random", r);
if (buf.len != 0) {
self.state.squeeze(buf);
} else {
self.state.permute();
}
mem.set(u8, self.state.toSlice()[0..std.crypto.core.Gimli.RATE], 0);
}
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