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102 lines
2.3 KiB
JavaScript
102 lines
2.3 KiB
JavaScript
/*
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* A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined
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* in FIPS PUB 180-1
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* Version 2.1a Copyright Paul Johnston 2000 - 2002.
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* Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
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* Distributed under the BSD License
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* See http://pajhome.org.uk/crypt/md5 for details.
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*/
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var helpers = require('./helpers');
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/*
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* Calculate the SHA-1 of an array of big-endian words, and a bit length
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*/
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function core_sha1(x, len)
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{
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/* append padding */
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x[len >> 5] |= 0x80 << (24 - len % 32);
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x[((len + 64 >> 9) << 4) + 15] = len;
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var w = Array(80);
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var a = 1732584193;
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var b = -271733879;
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var c = -1732584194;
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var d = 271733878;
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var e = -1009589776;
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for(var i = 0; i < x.length; i += 16)
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{
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var olda = a;
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var oldb = b;
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var oldc = c;
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var oldd = d;
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var olde = e;
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for(var j = 0; j < 80; j++)
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{
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if(j < 16) w[j] = x[i + j];
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else w[j] = rol(w[j-3] ^ w[j-8] ^ w[j-14] ^ w[j-16], 1);
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var t = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)),
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safe_add(safe_add(e, w[j]), sha1_kt(j)));
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e = d;
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d = c;
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c = rol(b, 30);
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b = a;
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a = t;
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}
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a = safe_add(a, olda);
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b = safe_add(b, oldb);
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c = safe_add(c, oldc);
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d = safe_add(d, oldd);
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e = safe_add(e, olde);
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}
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return Array(a, b, c, d, e);
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}
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/*
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* Perform the appropriate triplet combination function for the current
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* iteration
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*/
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function sha1_ft(t, b, c, d)
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{
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if(t < 20) return (b & c) | ((~b) & d);
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if(t < 40) return b ^ c ^ d;
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if(t < 60) return (b & c) | (b & d) | (c & d);
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return b ^ c ^ d;
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}
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/*
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* Determine the appropriate additive constant for the current iteration
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*/
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function sha1_kt(t)
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{
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return (t < 20) ? 1518500249 : (t < 40) ? 1859775393 :
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(t < 60) ? -1894007588 : -899497514;
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}
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/*
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* Add integers, wrapping at 2^32. This uses 16-bit operations internally
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* to work around bugs in some JS interpreters.
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*/
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function safe_add(x, y)
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{
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var lsw = (x & 0xFFFF) + (y & 0xFFFF);
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var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
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return (msw << 16) | (lsw & 0xFFFF);
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}
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/*
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* Bitwise rotate a 32-bit number to the left.
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*/
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function rol(num, cnt)
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{
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return (num << cnt) | (num >>> (32 - cnt));
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}
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module.exports = function sha1(buf) {
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return helpers.hash(buf, core_sha1, 20, true);
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};
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