marvin
75 lines
3.1 KiB
JavaScript
75 lines
3.1 KiB
JavaScript
import crypto from "node:crypto";
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// Minimal RFC 4648 base32 (no padding), and RFC 6238 TOTP on top of RFC 4226 HOTP.
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// Implemented against Node's built-in crypto only — no third-party dependency.
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const BASE32_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
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export function base32Encode(buffer) {
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let bits = "";
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for (const byte of buffer) bits += byte.toString(2).padStart(8, "0");
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let output = "";
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for (let i = 0; i + 5 <= bits.length; i += 5) output += BASE32_ALPHABET[parseInt(bits.slice(i, i + 5), 2)];
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const remainder = bits.length % 5;
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if (remainder) output += BASE32_ALPHABET[parseInt(bits.slice(bits.length - remainder).padEnd(5, "0"), 2)];
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return output;
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}
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export function base32Decode(value) {
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const cleaned = String(value || "").toUpperCase().replace(/[^A-Z2-7]/g, "");
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let bits = "";
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for (const char of cleaned) {
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const index = BASE32_ALPHABET.indexOf(char);
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if (index < 0) continue;
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bits += index.toString(2).padStart(5, "0");
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}
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const bytes = [];
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for (let i = 0; i + 8 <= bits.length; i += 8) bytes.push(parseInt(bits.slice(i, i + 8), 2));
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return Buffer.from(bytes);
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}
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export function generateTotpSecret() {
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return base32Encode(crypto.randomBytes(20)); // 160-bit key, standard for authenticator apps
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}
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function hotp(secretBuffer, counter, digits = 6) {
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const counterBuffer = Buffer.alloc(8);
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counterBuffer.writeBigUInt64BE(BigInt(counter));
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const hmac = crypto.createHmac("sha1", secretBuffer).update(counterBuffer).digest();
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const offset = hmac[hmac.length - 1] & 0x0f;
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const binary = ((hmac[offset] & 0x7f) << 24) | ((hmac[offset + 1] & 0xff) << 16) | ((hmac[offset + 2] & 0xff) << 8) | (hmac[offset + 3] & 0xff);
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return String(binary % 10 ** digits).padStart(digits, "0");
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}
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export function totpAt(base32Secret, forTime = Date.now(), step = 30, digits = 6) {
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const counter = Math.floor(forTime / 1000 / step);
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return hotp(base32Decode(base32Secret), counter, digits);
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}
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// Accepts a code from the current step or one step on either side, to tolerate normal clock drift.
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export function verifyTotp(base32Secret, code, { step = 30, digits = 6, window = 1, forTime = Date.now() } = {}) {
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const candidate = String(code || "").trim().replace(/\s+/g, "");
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if (!/^\d{6,8}$/.test(candidate)) return false;
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const secretBuffer = base32Decode(base32Secret);
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const baseCounter = Math.floor(forTime / 1000 / step);
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for (let offset = -window; offset <= window; offset++) {
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const expected = hotp(secretBuffer, baseCounter + offset, digits);
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if (crypto.timingSafeEqual(Buffer.from(expected), Buffer.from(candidate.padStart(digits, "0")))) return true;
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}
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return false;
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}
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export function otpauthUri({ secret, username, issuer = "Site Gateway" }) {
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const label = `${encodeURIComponent(issuer)}:${encodeURIComponent(username)}`;
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return `otpauth://totp/${label}?secret=${secret}&issuer=${encodeURIComponent(issuer)}&algorithm=SHA1&digits=6&period=30`;
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}
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export function generateRecoveryCodes(count = 10) {
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const codes = [];
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for (let i = 0; i < count; i++) {
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const raw = crypto.randomBytes(5).toString("hex").toUpperCase(); // 10 hex chars
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codes.push(`${raw.slice(0, 5)}-${raw.slice(5, 10)}`);
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}
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return codes;
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}
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