The number of bytes to generate. The size must not be larger than 2**31 - 1.
Generates cryptographically strong pseudorandom data. The size argument
is a number indicating the number of bytes to generate.
If a callback function is provided, the bytes are generated asynchronously
and the callback function is invoked with two arguments: err and buf.
If an error occurs, err will be an Error object; otherwise it is null. Thebuf argument is a Buffer containing the generated bytes.
// Asynchronous
const {
randomBytes
} = await import('crypto');
randomBytes(256, (err, buf) => {
if (err) throw err;
console.log(`${buf.length} bytes of random data: ${buf.toString('hex')}`);
});
If the callback function is not provided, the random bytes are generated
synchronously and returned as a Buffer. An error will be thrown if
there is a problem generating the bytes.
// Synchronous
const {
randomBytes
} = await import('crypto');
const buf = randomBytes(256);
console.log(
`${buf.length} bytes of random data: ${buf.toString('hex')}`);
The crypto.randomBytes() method will not complete until there is
sufficient entropy available.
This should normally never take longer than a few milliseconds. The only time
when generating the random bytes may conceivably block for a longer period of
time is right after boot, when the whole system is still low on entropy.
This API uses libuv's threadpool, which can have surprising and
negative performance implications for some applications; see the UV_THREADPOOL_SIZE documentation for more information.
The asynchronous version of crypto.randomBytes() is carried out in a single
threadpool request. To minimize threadpool task length variation, partition
large randomBytes requests when doing so as part of fulfilling a client
request.
if the callback function is not provided.
The number of bytes to generate. The size must not be larger than 2**31 - 1.
Generated using TypeDoc
Generates cryptographically strong pseudorandom data. The
sizeargument is a number indicating the number of bytes to generate.If a
callbackfunction is provided, the bytes are generated asynchronously and thecallbackfunction is invoked with two arguments:errandbuf. If an error occurs,errwill be anErrorobject; otherwise it isnull. Thebufargument is aBuffercontaining the generated bytes.If the
callbackfunction is not provided, the random bytes are generated synchronously and returned as aBuffer. An error will be thrown if there is a problem generating the bytes.The
crypto.randomBytes()method will not complete until there is sufficient entropy available. This should normally never take longer than a few milliseconds. The only time when generating the random bytes may conceivably block for a longer period of time is right after boot, when the whole system is still low on entropy.This API uses libuv's threadpool, which can have surprising and negative performance implications for some applications; see the
UV_THREADPOOL_SIZEdocumentation for more information.The asynchronous version of
crypto.randomBytes()is carried out in a single threadpool request. To minimize threadpool task length variation, partition largerandomBytesrequests when doing so as part of fulfilling a client request.Returns
if the
callbackfunction is not provided.