SubtleCrypto: deriveBits() メソッド

deriveBits(algorithm, baseKey, length) 

async function deriveSharedSecret(privateKey, publicKey) { const sharedSecret = await window.crypto.subtle.deriveBits( { name: "ECDH", namedCurve: "P-384", public: publicKey, }, privateKey, 128, ); const buffer = new Uint8Array(sharedSecret, 0, 5); const sharedSecretValue = document.querySelector(".ecdh .derived-bits-value"); sharedSecretValue.classList.add("fade-in"); sharedSecretValue.addEventListener("animationend", () => { sharedSecretValue.classList.remove("fade-in"); }); sharedSecretValue.textContent = `${buffer}…[${sharedSecret.byteLength} bytes total]`; } // Generate 2 ECDH key pairs: one for Alice and one for Bob // In more normal usage, they would generate their key pairs // separately and exchange public keys securely const generateAlicesKeyPair = window.crypto.subtle.generateKey( { name: "ECDH", namedCurve: "P-384", }, false, ["deriveBits"], ); const generateBobsKeyPair = window.crypto.subtle.generateKey( { name: "ECDH", namedCurve: "P-384", }, false, ["deriveBits"], ); Promise.all([generateAlicesKeyPair, generateBobsKeyPair]).then((values) => { const alicesKeyPair = values[0]; const bobsKeyPair = values[1]; const deriveBitsButton = document.querySelector(".ecdh .derive-bits-button"); deriveBitsButton.addEventListener("click", () => { // Alice then generates a secret using her private key and Bob's public key. // Bob could generate the same secret using his private key and Alice's public key. deriveSharedSecret(alicesKeyPair.privateKey, bobsKeyPair.publicKey); }); }); 

let salt; /* Get some key material to use as input to the deriveBits method. The key material is a password supplied by the user. */ function getKeyMaterial() { const password = window.prompt("Enter your password"); const enc = new TextEncoder(); return window.crypto.subtle.importKey( "raw", enc.encode(password), { name: "PBKDF2" }, false, ["deriveBits", "deriveKey"], ); } /* Derive some bits from a password supplied by the user. */ async function getDerivedBits() { const keyMaterial = await getKeyMaterial(); salt = window.crypto.getRandomValues(new Uint8Array(16)); const derivedBits = await window.crypto.subtle.deriveBits( { name: "PBKDF2", salt, iterations: 100000, hash: "SHA-256", }, keyMaterial, 256, ); const buffer = new Uint8Array(derivedBits, 0, 5); const derivedBitsValue = document.querySelector( ".pbkdf2 .derived-bits-value", ); derivedBitsValue.classList.add("fade-in"); derivedBitsValue.addEventListener("animationend", () => { derivedBitsValue.classList.remove("fade-in"); }); derivedBitsValue.textContent = `${buffer}…[${derivedBits.byteLength} bytes total]`; } const deriveBitsButton = document.querySelector(".pbkdf2 .derive-bits-button"); deriveBitsButton.addEventListener("click", () => { getDerivedBits(); });