55 lines
1.5 KiB
Lua
55 lines
1.5 KiB
Lua
local expect = require "cc.expect".expect
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local blake3 = require "ccryptolib.blake3"
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local chacha20 = require "ccryptolib.chacha20"
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local util = require "ccryptolib.internal.util"
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local lassert = util.lassert
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-- Extract local context.
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local ctx = {
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"ccryptolib 2023-04-11T19:43Z random.lua initialization context",
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os.epoch("utc"),
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os.epoch("ingame"),
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math.random(0, 2 ^ 24 - 1),
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math.random(0, 2 ^ 24 - 1),
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tostring({}),
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tostring({}),
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}
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local state = blake3.digest(table.concat(ctx, "|"))
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local initialized = false
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--- Mixes entropy into the generator, and marks it as initialized.
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--- @param seed string The seed data.
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local function init(seed)
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expect(1, seed, "string")
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state = blake3.digestKeyed(state, seed)
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initialized = true
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end
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--- Mixes extra entropy into the generator state.
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--- @param data string The additional entropy to mix.
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local function mix(data)
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expect(1, data, "string")
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state = blake3.digestKeyed(state, data)
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end
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--- Generates random bytes.
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--- @param len number The desired output length.
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--- @return string bytes
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local function random(len)
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expect(1, len, "number")
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lassert(initialized, "attempt to use an uninitialized random generator", 2)
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local msg = ("\0"):rep(math.max(len, 0) + 32)
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local nonce = ("\0"):rep(12)
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local out = chacha20.crypt(state, nonce, msg, 8, 0)
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state = out:sub(1, 32)
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return out:sub(33)
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end
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return {
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init = init,
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mix = mix,
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random = random,
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}
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