Crypto API

randomUUID()

Generate random UUID in browser console

this.crypto.randomUUID();
// '7ed9244d-6464-4ed7-a0a0-800a5e492641'

getRandomValues()

Get cryptographically strong random values

  • To guarantee enough performance, implementations are not using a truly random number generator, but they are using a pseudo-random number generator seeded with a value with enough entropy
  • The pseudo-random number generator algorithm (PRNG) may vary across user agents, but is suitable for cryptographic purposes

Syntax

Argument

Takes integer-based typed array as an argument

  • one of:
    • Int8Array, Uint8Array, Uint8ClampedArray, Int16Array, Uint16Array, Int32Array, Uint32Array, BigInt64Array, BigUint64Array (but not Float32Array nor Float64Array)
getRandomValues(typedArray)

Example

const array = new Uint32Array(10);
self.crypto.getRandomValues(array);

for (const num of array) {
  console.log(num);
}

Return Value

All elements in the array will be overwritten with random numbers

  • typedArray is modified in-place, and no copy is made

Security

Although more random than Math.random(), it's not guaranteed to be running in a secure context

MDN recommends to use generateKey() instead when random value must be used as an encryption key