QingpingMeng

function longToByteArray(/*long*/ long: number): Uint8Array {
  const byteArray = new Uint8Array(8)
  for (let index = 0; index < byteArray.length; index++) {
    // tslint:disable-next-line: no-bitwise
    const byte = long & 0xff
    byteArray[index] = byte
    // tslint:disable-next-line: no-bitwise
    long = (long - byte) >> 8
  }

QingpingMeng

function arrayBufferToBase64(buffer: ArrayBuffer): string {
  let binary = ''
  const bytes = new Uint8Array(buffer)
  const len = bytes.byteLength
  for (let i = 0; i < len; i++) {
    binary += String.fromCharCode(bytes[i])
  }
  return window.btoa(binary)
}

QingpingMeng

This is an example to demo how you generate the RSA key pair from server side(.NetCore 3.1) and pass the public key to the client(Browser) for encrypting the data that <= 245 bytes.

RSA-2048 can only support to encrypt up to 245 bytes data.

Generate RSA key pair in C# (.Net Core 3.1):

using var rsaProvider = new RSACng();
// spki is used for browser side encryption
var spki = Convert.ToBase64String(rsaProvider.ExportSubjectPublicKeyInfo());
var encodedPrivateKey = Convert.ToBase64String(rsaProvider.ExportPkcs8PrivateKey());