의사 난수 생성: Crypto.getRandomValues

typedArray = cryptoObj.getRandomValues(typedArray);

var array = new Uint32Array(10);
window.crypto.getRandomValues(array);

지원되는 알고리즘

브라우저측: 공개키로 암호화

const result = crypto.subtle.importKey(
    format, // raw(AESの鍵),pkcs8（RSAのプライベート鍵）,spki(SubjectPublicKeyInfo:RSAまたはElliptic Curveの公開鍵),jwk(JSON Web Key)
    keyData, // キーデータ。ArrayBuffer、TypedArray、JSONWebKeyオブジェクト
    algorithm, //　①、RsaHashedImportParams ：RSA-OAEP、RSA-PSS。②、EcKeyImportParams：ECDSA、ECDH。③、HmacImportParams ：HMAC　④、{ "name": ALGORITHM }：AES-CTR, AES-CBC, AES-GCM、AES-KW。　⑤、PBKDF2
    extractable, // true/false。 SubtleCrypto.exportKey() or SubtleCrypto.wrapKey()メソッドを使うか
    usages // ["encrypt", "decrypt", "sign", "verify", "deriveKey", "deriveBits", "wrapKey", "unwrapKey"]
);

 // from https://developers.google.com/web/updates/2012/06/How-to-convert-ArrayBuffer-to-and-from-String
  function str2ab(str) {
    const buf = new ArrayBuffer(str.length);
    const bufView = new Uint8Array(buf);
    for (let i = 0, strLen = str.length; i < strLen; i++) {
      bufView[i] = str.charCodeAt(i);
    }
    return buf;
  }

  const pemEncodedKey = `-----BEGIN PUBLIC KEY-----
.......
-----END PUBLIC KEY-----`;

  function importRsaKey(pem) {
    const pemHeader = "-----BEGIN PUBLIC KEY-----";
    const pemFooter = "-----END PUBLIC KEY-----";
    const pemContents = pem.substring(pemHeader.length, pem.length - pemFooter.length);
    // base64 decode the string to get the binary data
    const binaryDerString = window.atob(pemContents);
    // convert from a binary string to an ArrayBuffer
    const binaryDer = str2ab(binaryDerString);

    return window.crypto.subtle.importKey(
      "spki",
      binaryDer,
      {
        name: "RSA-OAEP",
        hash: "SHA-256"
      },
      true,
      ["encrypt"]
    );
  }

function encryptMessage(publicKey, message) {
  let enc = new TextEncoder();
  let encoded = enc.encode(message);
  return window.crypto.subtle.encrypt(
    {
      name: "RSA-OAEP"
    },
    publicKey,
    encoded
  );
}

서버 측 (Node.js) : 개인 키로 해독

const webcrypto = require("@peculiar/webcrypto");
const crypto = new webcrypto.Crypto();
const {TextDecoder} = require('util');

const pemText = "xxxxx";
const pkcs8 = Buffer.from(pemText, "base64");
const key = crypto.subtle.importKey("pkcs8", pkcs8, { name: "RSA-OAEP", hash: "SHA-256" }, true, ["decrypt"]);

const decryptedStr = await crypto.subtle.decrypt("RSA-OAEP", key, Buffer.from(encryptedMessage, "base64"));
const result = new TextDecoder("utf-8").decode(new Uint8Array(decryptedStr ));

기타: 대칭 암호화 예(AES-GCM)

function encryptMessage(key, message) {
  let enc = new TextEncoder();
  let encoded = enc.encode(message);
  iv = window.crypto.getRandomValues(new Uint8Array(12));
  return window.crypto.subtle.encrypt(
    {
      name: "AES-GCM",
      iv: iv
    },
    key,
    encoded
  );
}