328 lines
9.3 KiB
JavaScript
328 lines
9.3 KiB
JavaScript
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/**
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* Secure Hash Algorithm with 256-bit digest (SHA-256) implementation.
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*
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* See FIPS 180-2 for details.
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*
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* @author Dave Longley
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*
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* Copyright (c) 2010-2015 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 sha256 = module.exports = forge.sha256 = forge.sha256 || {};
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forge.md.sha256 = forge.md.algorithms.sha256 = sha256;
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/**
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* Creates a SHA-256 message digest object.
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*
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* @return a message digest object.
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*/
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sha256.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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// SHA-256 state contains eight 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(64);
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// message digest object
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var md = {
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algorithm: 'sha256',
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blockLength: 64,
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digestLength: 32,
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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: 0x6A09E667,
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h1: 0xBB67AE85,
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h2: 0x3C6EF372,
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h3: 0xA54FF53A,
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h4: 0x510E527F,
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h5: 0x9B05688C,
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h6: 0x1F83D9AB,
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h7: 0x5BE0CD19
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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 SHA-256 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 big-endian order; since length
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// is stored in bytes we multiply by 8 and add carry from next int
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var next, carry;
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var bits = md.fullMessageLength[0] * 8;
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for(var i = 0; i < md.fullMessageLength.length - 1; ++i) {
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next = md.fullMessageLength[i + 1] * 8;
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carry = (next / 0x100000000) >>> 0;
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bits += carry;
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finalBlock.putInt32(bits >>> 0);
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bits = next >>> 0;
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}
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finalBlock.putInt32(bits);
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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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h4: _state.h4,
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h5: _state.h5,
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h6: _state.h6,
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h7: _state.h7
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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.putInt32(s2.h0);
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rval.putInt32(s2.h1);
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rval.putInt32(s2.h2);
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rval.putInt32(s2.h3);
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rval.putInt32(s2.h4);
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rval.putInt32(s2.h5);
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rval.putInt32(s2.h6);
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rval.putInt32(s2.h7);
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return rval;
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};
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return md;
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};
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// sha-256 padding bytes not initialized yet
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var _padding = null;
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var _initialized = false;
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// table of constants
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var _k = null;
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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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// create K table for SHA-256
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_k = [
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0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
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0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
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0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
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0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
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0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
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0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
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0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
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0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
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0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
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0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
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0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
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0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
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0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
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0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
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0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
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0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2];
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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 a SHA-256 state with the given byte buffer.
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*
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* @param s the SHA-256 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 t1, t2, s0, s1, ch, maj, i, a, b, c, d, e, f, g, h;
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var len = bytes.length();
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while(len >= 64) {
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// the w array will be populated with sixteen 32-bit big-endian words
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// and then extended into 64 32-bit words according to SHA-256
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for(i = 0; i < 16; ++i) {
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w[i] = bytes.getInt32();
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}
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for(; i < 64; ++i) {
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// XOR word 2 words ago rot right 17, rot right 19, shft right 10
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t1 = w[i - 2];
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t1 =
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((t1 >>> 17) | (t1 << 15)) ^
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((t1 >>> 19) | (t1 << 13)) ^
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(t1 >>> 10);
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// XOR word 15 words ago rot right 7, rot right 18, shft right 3
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t2 = w[i - 15];
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t2 =
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((t2 >>> 7) | (t2 << 25)) ^
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((t2 >>> 18) | (t2 << 14)) ^
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(t2 >>> 3);
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// sum(t1, word 7 ago, t2, word 16 ago) modulo 2^32
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w[i] = (t1 + w[i - 7] + t2 + w[i - 16]) | 0;
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}
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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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e = s.h4;
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f = s.h5;
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g = s.h6;
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h = s.h7;
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// round function
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for(i = 0; i < 64; ++i) {
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// Sum1(e)
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s1 =
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((e >>> 6) | (e << 26)) ^
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((e >>> 11) | (e << 21)) ^
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((e >>> 25) | (e << 7));
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// Ch(e, f, g) (optimized the same way as SHA-1)
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ch = g ^ (e & (f ^ g));
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// Sum0(a)
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s0 =
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((a >>> 2) | (a << 30)) ^
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((a >>> 13) | (a << 19)) ^
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((a >>> 22) | (a << 10));
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// Maj(a, b, c) (optimized the same way as SHA-1)
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maj = (a & b) | (c & (a ^ b));
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// main algorithm
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t1 = h + s1 + ch + _k[i] + w[i];
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t2 = s0 + maj;
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h = g;
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g = f;
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f = e;
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// `>>> 0` necessary to avoid iOS/Safari 10 optimization bug
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// can't truncate with `| 0`
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e = (d + t1) >>> 0;
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d = c;
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c = b;
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b = a;
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// `>>> 0` necessary to avoid iOS/Safari 10 optimization bug
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// can't truncate with `| 0`
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a = (t1 + t2) >>> 0;
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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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s.h4 = (s.h4 + e) | 0;
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s.h5 = (s.h5 + f) | 0;
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s.h6 = (s.h6 + g) | 0;
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s.h7 = (s.h7 + h) | 0;
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len -= 64;
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}
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}
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