74 lines
2.9 KiB
JavaScript
74 lines
2.9 KiB
JavaScript
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// Generated, do not edit. sha256:c9e44c618374bc6218029ec68095d9d8a62c6e5839ffe1dd3084b46600ccb118
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import {
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secp256k1, sha256, chacha20, hkdfExtract, hkdfExpand, hmac, base64,
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hexToBytes, utf8ToBytes, concatBytes,
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} from '../vendor/crypto/noble-scure.js';
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const VERSION = 2;
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const SALT = utf8ToBytes('nip44-v2');
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const MIN = 1;
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const MAX = 65535;
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const asBytes = (x) => (typeof x === 'string' ? hexToBytes(x) : x);
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export function conversationKey(secret, pubkey) {
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const shared = secp256k1.getSharedSecret(asBytes(secret), concatBytes(Uint8Array.of(2), asBytes(pubkey)));
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return hkdfExtract(sha256, shared.subarray(1, 33), SALT);
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}
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export function messageKeys(convKey, nonce) {
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const keys = hkdfExpand(sha256, asBytes(convKey), asBytes(nonce), 76);
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return { chachaKey: keys.subarray(0, 32), chachaNonce: keys.subarray(32, 44), hmacKey: keys.subarray(44, 76) };
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}
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export function paddedLength(len) {
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if (len <= 32) return 32;
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const next = 1 << (Math.floor(Math.log2(len - 1)) + 1);
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const chunk = next <= 256 ? 32 : next / 8;
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return chunk * (Math.floor((len - 1) / chunk) + 1);
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}
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function pad(text) {
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const bytes = utf8ToBytes(text);
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if (bytes.length < MIN || bytes.length > MAX) throw new Error(`A NIP-44 message is ${MIN} to ${MAX} bytes.`);
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const out = new Uint8Array(2 + paddedLength(bytes.length));
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out[0] = bytes.length >> 8;
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out[1] = bytes.length & 0xff;
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out.set(bytes, 2);
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return out;
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}
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function unpad(padded) {
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const len = (padded[0] << 8) | padded[1];
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if (len < MIN || padded.length !== 2 + paddedLength(len)) throw new Error('Invalid padding.');
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return new TextDecoder('utf-8', { fatal: true }).decode(padded.subarray(2, 2 + len));
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}
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function sameBytes(a, b) {
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if (a.length !== b.length) return false;
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let d = 0;
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for (let i = 0; i < a.length; i++) d |= a[i] ^ b[i];
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return d === 0;
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}
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export function encrypt(text, convKey, nonce = crypto.getRandomValues(new Uint8Array(32))) {
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const n = asBytes(nonce);
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const { chachaKey, chachaNonce, hmacKey } = messageKeys(convKey, n);
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const ciphertext = chacha20(chachaKey, chachaNonce, pad(text));
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const mac = hmac(sha256, hmacKey, concatBytes(n, ciphertext));
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return base64.encode(concatBytes(Uint8Array.of(VERSION), n, ciphertext, mac));
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}
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export function decrypt(payload, convKey) {
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const p = String(payload ?? '');
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if (!p || p[0] === '#') throw new Error('Unknown NIP-44 version.');
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if (p.length < 132 || p.length > 87472) throw new Error('Invalid NIP-44 payload length.');
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const data = base64.decode(p);
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if (data[0] !== VERSION) throw new Error(`Unknown NIP-44 version ${data[0]}.`);
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const nonce = data.subarray(1, 33);
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const ciphertext = data.subarray(33, data.length - 32);
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const mac = data.subarray(data.length - 32);
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const { chachaKey, chachaNonce, hmacKey } = messageKeys(convKey, nonce);
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if (!sameBytes(mac, hmac(sha256, hmacKey, concatBytes(nonce, ciphertext)))) throw new Error('Invalid MAC.');
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return unpad(chacha20(chachaKey, chachaNonce, ciphertext));
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}
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