mirror of
https://github.com/seiichiro0185/sailotp.git
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91 lines
3.3 KiB
JavaScript
91 lines
3.3 KiB
JavaScript
/*
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* Copyright (c) 2013, Stefan Brand <seiichiro@seiichiro0185.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice, this
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* list of conditions and the following disclaimer in the documentation and/or other
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* materials provided with the distribution.
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*
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* 3. The names of the contributors may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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.import "./sha.js" as SHA
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// *** Helper Functions *** //
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// Decimal to HEX
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function dec2hex(s) { return (s < 15.5 ? '0' : '') + Math.round(s).toString(16); }
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// HEX to Decimal
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function hex2dec(s) { return parseInt(s, 16); }
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// Convert Base32-secret to HEX Value
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function base32tohex(base32) {
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var base32chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
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var bits = "";
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var hex = "";
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for (var i = 0; i < base32.length; i++) {
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var val = base32chars.indexOf(base32.charAt(i).toUpperCase());
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bits += leftpad(val.toString(2), 5, '0');
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}
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for (var i = 0; i+4 <= bits.length; i+=4) {
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var chunk = bits.substr(i, 4);
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hex = hex + parseInt(chunk, 2).toString(16) ;
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}
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return hex;
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}
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// Pad Strings to given length
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function leftpad(str, len, pad) {
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if (len + 1 >= str.length) {
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str = Array(len + 1 - str.length).join(pad) + str;
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}
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return str;
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}
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// *** Main Function *** //
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// Calculate an OTP-Value from the given secret
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// Parameter is the secret key in Base32-notation
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function calcOTP(secret) {
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// Convert the key to HEX
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var key = base32tohex(secret);
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// Get current Time in UNIX Timestamp format (Seconds since 01.01.1970 00:00 UTC)
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var epoch = Math.round(new Date().getTime() / 1000.0);
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// Get last full 30 / 60 Seconds and convert to HEX
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var time = leftpad(dec2hex(Math.floor(epoch / 30)), 16, '0');
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// Calculate the SHA-1 HMAC Value from time and key
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var hmacObj = new SHA.jsSHA(time, 'HEX');
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var hmac = hmacObj.getHMAC(key, 'HEX', 'SHA-1', "HEX");
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// Finally convert the HMAC-Value to the corresponding 6-digit token
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var offset = hex2dec(hmac.substring(hmac.length - 1));
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var otp = (hex2dec(hmac.substr(offset * 2, 8)) & hex2dec('7fffffff')) + '';
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otp = (otp).substr(otp.length - 6, 6);
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// return the calculated token
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return otp;
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}
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