next.js/packages/next/src/server/node-environment-extensions/web-crypto.tsx

/**
 * We extend Web Crypto APIs during builds and revalidates to ensure that prerenders don't observe random bytes
 * When cacheComponents is enabled. Random bytes are a form of IO even if they resolve synchronously. When cacheComponents is
 * enabled we need to ensure that random bytes are excluded from prerenders unless they are cached.
 *
 *
 * The extensions here never error nor alter the underlying return values and thus should be transparent to callers.
 */

import { io } from './utils'

let webCrypto: typeof crypto
if (process.env.NEXT_RUNTIME === 'edge') {
  webCrypto = crypto
} else {
  if (typeof crypto === 'undefined') {
    // @ts-expect-error -- TODO: Is this actually safe?
    webCrypto = (require('node:crypto') as typeof import('node:crypto'))
      .webcrypto
  } else {
    webCrypto = crypto
  }
}

const getRandomValuesExpression = '`crypto.getRandomValues()`'
try {
  const _getRandomValues = webCrypto.getRandomValues
  webCrypto.getRandomValues = function getRandomValues() {
    io(getRandomValuesExpression, 'crypto')
    return _getRandomValues.apply(webCrypto, arguments as any)
  }
} catch {
  console.error(
    `Failed to install ${getRandomValuesExpression} extension. When using \`experimental.cacheComponents\` calling this function will not correctly trigger dynamic behavior.`
  )
}

const randomUUIDExpression = '`crypto.randomUUID()`'
try {
  const _randomUUID = webCrypto.randomUUID
  webCrypto.randomUUID = function randomUUID() {
    io(randomUUIDExpression, 'crypto')
    return _randomUUID.apply(webCrypto, arguments as any)
  } as typeof _randomUUID
} catch {
  console.error(
    `Failed to install ${getRandomValuesExpression} extension. When using \`experimental.cacheComponents\` calling this function will not correctly trigger dynamic behavior.`
  )
}