43 lines
1.3 KiB
JavaScript
43 lines
1.3 KiB
JavaScript
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/* https://github.com/turistu/totp-in-javascript/blob/main/totp.js */
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async function otp_totp(key, secs = 30, digits = 6) {
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return otp_hotp(otp_unbase32(key), otp_pack64bu(Date.now() / 1000 / secs), digits);
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}
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async function otp_hotp(key, counter, digits) {
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let y = self.crypto.subtle;
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if (!y) throw Error("no self.crypto.subtle object available");
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let k = await y.importKey("raw", key, { name: "HMAC", hash: "SHA-1" }, false, ["sign"]);
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return otp_hotp_truncate(await y.sign("HMAC", k, counter), digits);
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}
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function otp_hotp_truncate(buf, digits) {
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let a = new Uint8Array(buf),
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i = a[19] & 0xf;
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return otp_fmt(
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10,
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digits,
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(((a[i] & 0x7f) << 24) | (a[i + 1] << 16) | (a[i + 2] << 8) | a[i + 3]) % 10 ** digits,
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);
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}
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function otp_fmt(base, width, num) {
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return num.toString(base).padStart(width, "0");
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}
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function otp_unbase32(s) {
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let t = (s.toLowerCase().match(/\S/g) || [])
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.map((c) => {
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let i = "abcdefghijklmnopqrstuvwxyz234567".indexOf(c);
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if (i < 0) throw Error(`bad char '${c}' in key`);
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return otp_fmt(2, 5, i);
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})
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.join("");
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if (t.length < 8) throw Error("key too short");
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return new Uint8Array(t.match(/.{8}/g).map((d) => parseInt(d, 2)));
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}
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function otp_pack64bu(v) {
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let b = new ArrayBuffer(8),
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d = new DataView(b);
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d.setUint32(0, v / 2 ** 32);
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d.setUint32(4, v);
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return b;
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}
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