/**
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* Message Digest Algorithm 5 with 128-bit digest (MD5) implementation.
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*
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* @author Dave Longley
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*
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* Copyright (c) 2010-2014 Digital Bazaar, Inc.
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*/
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var forge = require('./forge');
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require('./md');
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require('./util');
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var md5 = module.exports = forge.md5 = forge.md5 || {};
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forge.md.md5 = forge.md.algorithms.md5 = md5;
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/**
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* Creates an MD5 message digest object.
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*
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* @return a message digest object.
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*/
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md5.create = function() {
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// do initialization as necessary
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if(!_initialized) {
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_init();
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}
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// MD5 state contains four 32-bit integers
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var _state = null;
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// input buffer
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var _input = forge.util.createBuffer();
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// used for word storage
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var _w = new Array(16);
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// message digest object
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var md = {
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algorithm: 'md5',
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blockLength: 64,
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digestLength: 16,
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// 56-bit length of message so far (does not including padding)
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messageLength: 0,
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// true message length
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fullMessageLength: null,
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// size of message length in bytes
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messageLengthSize: 8
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};
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/**
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* Starts the digest.
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*
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* @return this digest object.
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*/
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md.start = function() {
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// up to 56-bit message length for convenience
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md.messageLength = 0;
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// full message length (set md.messageLength64 for backwards-compatibility)
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md.fullMessageLength = md.messageLength64 = [];
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var int32s = md.messageLengthSize / 4;
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for(var i = 0; i < int32s; ++i) {
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md.fullMessageLength.push(0);
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}
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_input = forge.util.createBuffer();
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_state = {
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h0: 0x67452301,
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h1: 0xEFCDAB89,
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h2: 0x98BADCFE,
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h3: 0x10325476
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};
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return md;
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};
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// start digest automatically for first time
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md.start();
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/**
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* Updates the digest with the given message input. The given input can
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* treated as raw input (no encoding will be applied) or an encoding of
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* 'utf8' maybe given to encode the input using UTF-8.
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*
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* @param msg the message input to update with.
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* @param encoding the encoding to use (default: 'raw', other: 'utf8').
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*
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* @return this digest object.
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*/
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md.update = function(msg, encoding) {
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if(encoding === 'utf8') {
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msg = forge.util.encodeUtf8(msg);
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}
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// update message length
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var len = msg.length;
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md.messageLength += len;
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len = [(len / 0x100000000) >>> 0, len >>> 0];
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for(var i = md.fullMessageLength.length - 1; i >= 0; --i) {
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md.fullMessageLength[i] += len[1];
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len[1] = len[0] + ((md.fullMessageLength[i] / 0x100000000) >>> 0);
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md.fullMessageLength[i] = md.fullMessageLength[i] >>> 0;
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len[0] = (len[1] / 0x100000000) >>> 0;
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}
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// add bytes to input buffer
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_input.putBytes(msg);
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// process bytes
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_update(_state, _w, _input);
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// compact input buffer every 2K or if empty
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if(_input.read > 2048 || _input.length() === 0) {
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_input.compact();
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}
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return md;
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};
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/**
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* Produces the digest.
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*
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* @return a byte buffer containing the digest value.
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*/
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md.digest = function() {
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/* Note: Here we copy the remaining bytes in the input buffer and
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add the appropriate MD5 padding. Then we do the final update
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on a copy of the state so that if the user wants to get
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intermediate digests they can do so. */
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/* Determine the number of bytes that must be added to the message
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to ensure its length is congruent to 448 mod 512. In other words,
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the data to be digested must be a multiple of 512 bits (or 128 bytes).
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This data includes the message, some padding, and the length of the
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message. Since the length of the message will be encoded as 8 bytes (64
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bits), that means that the last segment of the data must have 56 bytes
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(448 bits) of message and padding. Therefore, the length of the message
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plus the padding must be congruent to 448 mod 512 because
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512 - 128 = 448.
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In order to fill up the message length it must be filled with
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padding that begins with 1 bit followed by all 0 bits. Padding
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must *always* be present, so if the message length is already
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congruent to 448 mod 512, then 512 padding bits must be added. */
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var finalBlock = forge.util.createBuffer();
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finalBlock.putBytes(_input.bytes());
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// compute remaining size to be digested (include message length size)
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var remaining = (
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md.fullMessageLength[md.fullMessageLength.length - 1] +
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md.messageLengthSize);
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// add padding for overflow blockSize - overflow
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// _padding starts with 1 byte with first bit is set (byte value 128), then
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// there may be up to (blockSize - 1) other pad bytes
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var overflow = remaining & (md.blockLength - 1);
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finalBlock.putBytes(_padding.substr(0, md.blockLength - overflow));
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// serialize message length in bits in little-endian order; since length
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// is stored in bytes we multiply by 8 and add carry
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var bits, carry = 0;
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for(var i = md.fullMessageLength.length - 1; i >= 0; --i) {
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bits = md.fullMessageLength[i] * 8 + carry;
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carry = (bits / 0x100000000) >>> 0;
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finalBlock.putInt32Le(bits >>> 0);
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}
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var s2 = {
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h0: _state.h0,
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h1: _state.h1,
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h2: _state.h2,
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h3: _state.h3
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};
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_update(s2, _w, finalBlock);
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var rval = forge.util.createBuffer();
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rval.putInt32Le(s2.h0);
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rval.putInt32Le(s2.h1);
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rval.putInt32Le(s2.h2);
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rval.putInt32Le(s2.h3);
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return rval;
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};
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return md;
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};
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// padding, constant tables for calculating md5
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var _padding = null;
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var _g = null;
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var _r = null;
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var _k = null;
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var _initialized = false;
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/**
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* Initializes the constant tables.
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*/
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function _init() {
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// create padding
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_padding = String.fromCharCode(128);
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_padding += forge.util.fillString(String.fromCharCode(0x00), 64);
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// g values
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_g = [
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
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1, 6, 11, 0, 5, 10, 15, 4, 9, 14, 3, 8, 13, 2, 7, 12,
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5, 8, 11, 14, 1, 4, 7, 10, 13, 0, 3, 6, 9, 12, 15, 2,
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0, 7, 14, 5, 12, 3, 10, 1, 8, 15, 6, 13, 4, 11, 2, 9];
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// rounds table
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_r = [
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7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
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5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20,
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4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
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6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21];
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// get the result of abs(sin(i + 1)) as a 32-bit integer
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_k = new Array(64);
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for(var i = 0; i < 64; ++i) {
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_k[i] = Math.floor(Math.abs(Math.sin(i + 1)) * 0x100000000);
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}
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// now initialized
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_initialized = true;
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}
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/**
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* Updates an MD5 state with the given byte buffer.
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*
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* @param s the MD5 state to update.
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* @param w the array to use to store words.
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* @param bytes the byte buffer to update with.
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*/
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function _update(s, w, bytes) {
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// consume 512 bit (64 byte) chunks
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var t, a, b, c, d, f, r, i;
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var len = bytes.length();
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while(len >= 64) {
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// initialize hash value for this chunk
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a = s.h0;
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b = s.h1;
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c = s.h2;
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d = s.h3;
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// round 1
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for(i = 0; i < 16; ++i) {
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w[i] = bytes.getInt32Le();
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f = d ^ (b & (c ^ d));
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t = (a + f + _k[i] + w[i]);
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r = _r[i];
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a = d;
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d = c;
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c = b;
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b += (t << r) | (t >>> (32 - r));
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}
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// round 2
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for(; i < 32; ++i) {
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f = c ^ (d & (b ^ c));
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t = (a + f + _k[i] + w[_g[i]]);
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r = _r[i];
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a = d;
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d = c;
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c = b;
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b += (t << r) | (t >>> (32 - r));
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}
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// round 3
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for(; i < 48; ++i) {
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f = b ^ c ^ d;
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t = (a + f + _k[i] + w[_g[i]]);
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r = _r[i];
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a = d;
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d = c;
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c = b;
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b += (t << r) | (t >>> (32 - r));
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}
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// round 4
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for(; i < 64; ++i) {
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f = c ^ (b | ~d);
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t = (a + f + _k[i] + w[_g[i]]);
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r = _r[i];
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a = d;
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d = c;
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c = b;
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b += (t << r) | (t >>> (32 - r));
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}
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// update hash state
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s.h0 = (s.h0 + a) | 0;
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s.h1 = (s.h1 + b) | 0;
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s.h2 = (s.h2 + c) | 0;
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s.h3 = (s.h3 + d) | 0;
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len -= 64;
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}
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}
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