const std = @import("std");
const min = std.math.min;
const mem = std.mem;
const Random = std.rand.Random;
const Self = @This();
const Ascon = std.crypto.core.Ascon(.Little);
state: Ascon,
const rate = 16;
pub const secret_seed_length = 32;
pub fn init(secret_seed: [secret_seed_length]u8) Self {
var self = Self{ .state = Ascon.initXof() };
self.addEntropy(&secret_seed);
return self;
}
pub fn addEntropy(self: *Self, bytes: []const u8) void {
comptime std.debug.assert(secret_seed_length % rate == 0);
var i: usize = 0;
while (i + rate < bytes.len) : (i += rate) {
self.state.addBytes(bytes[i..][0..rate]);
self.state.permuteR(8);
}
if (i != bytes.len) self.state.addBytes(bytes[i..]);
self.state.permute();
}
pub fn random(self: *Self) Random {
return Random.init(self, fill);
}
pub fn fill(self: *Self, buf: []u8) void {
var i: usize = 0;
while (true) {
const left = buf.len - i;
const n = min(left, rate);
self.state.extractBytes(buf[i..][0..n]);
if (left == 0) break;
self.state.permuteR(8);
i += n;
}
self.state.permuteRatchet(6, rate);
}