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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
// Copyright 2017 crypto-browserify. All rights reserved. MIT license.
import { Buffer } from "internal:deno_node/polyfills/buffer.ts";
import { nextTick } from "internal:deno_node/polyfills/_next_tick.ts";
// limit of Crypto.getRandomValues()
// https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
const MAX_BYTES = 65536;
// Node supports requesting up to this number of bytes
// https://github.com/nodejs/node/blob/master/lib/internal/crypto/random.js#L48
const MAX_UINT32 = 4294967295;
export function randomBytes(
size: number,
cb?: (err: Error | null, b: Buffer) => void,
) {
// phantomjs needs to throw
if (size > MAX_UINT32) {
throw new RangeError("requested too many random bytes");
}
const bytes = Buffer.allocUnsafe(size);
if (size > 0) { // getRandomValues fails on IE if size == 0
if (size > MAX_BYTES) { // this is the max bytes crypto.getRandomValues
// can do at once see https://developer.mozilla.org/en-US/docs/Web/API/window.crypto.getRandomValues
for (let generated = 0; generated < size; generated += MAX_BYTES) {
// buffer.slice automatically checks if the end is past the end of
// the buffer so we don't have to here
globalThis.crypto.getRandomValues(
bytes.slice(generated, generated + MAX_BYTES),
);
}
} else {
globalThis.crypto.getRandomValues(bytes);
}
}
if (typeof cb === "function") {
return nextTick(function () {
cb(null, bytes);
});
}
return bytes;
}
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