/**
|
* Secure Hash Algorithm with 256-bit digest (SHA-256) implementation.
|
*
|
* See FIPS 180-2 for details.
|
*
|
* @author Dave Longley
|
*
|
* Copyright (c) 2010-2015 Digital Bazaar, Inc.
|
*/
|
var forge = require('./forge');
|
require('./md');
|
require('./util');
|
|
var sha256 = module.exports = forge.sha256 = forge.sha256 || {};
|
forge.md.sha256 = forge.md.algorithms.sha256 = sha256;
|
|
/**
|
* Creates a SHA-256 message digest object.
|
*
|
* @return a message digest object.
|
*/
|
sha256.create = function() {
|
// do initialization as necessary
|
if(!_initialized) {
|
_init();
|
}
|
|
// SHA-256 state contains eight 32-bit integers
|
var _state = null;
|
|
// input buffer
|
var _input = forge.util.createBuffer();
|
|
// used for word storage
|
var _w = new Array(64);
|
|
// message digest object
|
var md = {
|
algorithm: 'sha256',
|
blockLength: 64,
|
digestLength: 32,
|
// 56-bit length of message so far (does not including padding)
|
messageLength: 0,
|
// true message length
|
fullMessageLength: null,
|
// size of message length in bytes
|
messageLengthSize: 8
|
};
|
|
/**
|
* Starts the digest.
|
*
|
* @return this digest object.
|
*/
|
md.start = function() {
|
// up to 56-bit message length for convenience
|
md.messageLength = 0;
|
|
// full message length (set md.messageLength64 for backwards-compatibility)
|
md.fullMessageLength = md.messageLength64 = [];
|
var int32s = md.messageLengthSize / 4;
|
for(var i = 0; i < int32s; ++i) {
|
md.fullMessageLength.push(0);
|
}
|
_input = forge.util.createBuffer();
|
_state = {
|
h0: 0x6A09E667,
|
h1: 0xBB67AE85,
|
h2: 0x3C6EF372,
|
h3: 0xA54FF53A,
|
h4: 0x510E527F,
|
h5: 0x9B05688C,
|
h6: 0x1F83D9AB,
|
h7: 0x5BE0CD19
|
};
|
return md;
|
};
|
// start digest automatically for first time
|
md.start();
|
|
/**
|
* Updates the digest with the given message input. The given input can
|
* treated as raw input (no encoding will be applied) or an encoding of
|
* 'utf8' maybe given to encode the input using UTF-8.
|
*
|
* @param msg the message input to update with.
|
* @param encoding the encoding to use (default: 'raw', other: 'utf8').
|
*
|
* @return this digest object.
|
*/
|
md.update = function(msg, encoding) {
|
if(encoding === 'utf8') {
|
msg = forge.util.encodeUtf8(msg);
|
}
|
|
// update message length
|
var len = msg.length;
|
md.messageLength += len;
|
len = [(len / 0x100000000) >>> 0, len >>> 0];
|
for(var i = md.fullMessageLength.length - 1; i >= 0; --i) {
|
md.fullMessageLength[i] += len[1];
|
len[1] = len[0] + ((md.fullMessageLength[i] / 0x100000000) >>> 0);
|
md.fullMessageLength[i] = md.fullMessageLength[i] >>> 0;
|
len[0] = ((len[1] / 0x100000000) >>> 0);
|
}
|
|
// add bytes to input buffer
|
_input.putBytes(msg);
|
|
// process bytes
|
_update(_state, _w, _input);
|
|
// compact input buffer every 2K or if empty
|
if(_input.read > 2048 || _input.length() === 0) {
|
_input.compact();
|
}
|
|
return md;
|
};
|
|
/**
|
* Produces the digest.
|
*
|
* @return a byte buffer containing the digest value.
|
*/
|
md.digest = function() {
|
/* Note: Here we copy the remaining bytes in the input buffer and
|
add the appropriate SHA-256 padding. Then we do the final update
|
on a copy of the state so that if the user wants to get
|
intermediate digests they can do so. */
|
|
/* Determine the number of bytes that must be added to the message
|
to ensure its length is congruent to 448 mod 512. In other words,
|
the data to be digested must be a multiple of 512 bits (or 128 bytes).
|
This data includes the message, some padding, and the length of the
|
message. Since the length of the message will be encoded as 8 bytes (64
|
bits), that means that the last segment of the data must have 56 bytes
|
(448 bits) of message and padding. Therefore, the length of the message
|
plus the padding must be congruent to 448 mod 512 because
|
512 - 128 = 448.
|
|
In order to fill up the message length it must be filled with
|
padding that begins with 1 bit followed by all 0 bits. Padding
|
must *always* be present, so if the message length is already
|
congruent to 448 mod 512, then 512 padding bits must be added. */
|
|
var finalBlock = forge.util.createBuffer();
|
finalBlock.putBytes(_input.bytes());
|
|
// compute remaining size to be digested (include message length size)
|
var remaining = (
|
md.fullMessageLength[md.fullMessageLength.length - 1] +
|
md.messageLengthSize);
|
|
// add padding for overflow blockSize - overflow
|
// _padding starts with 1 byte with first bit is set (byte value 128), then
|
// there may be up to (blockSize - 1) other pad bytes
|
var overflow = remaining & (md.blockLength - 1);
|
finalBlock.putBytes(_padding.substr(0, md.blockLength - overflow));
|
|
// serialize message length in bits in big-endian order; since length
|
// is stored in bytes we multiply by 8 and add carry from next int
|
var next, carry;
|
var bits = md.fullMessageLength[0] * 8;
|
for(var i = 0; i < md.fullMessageLength.length - 1; ++i) {
|
next = md.fullMessageLength[i + 1] * 8;
|
carry = (next / 0x100000000) >>> 0;
|
bits += carry;
|
finalBlock.putInt32(bits >>> 0);
|
bits = next >>> 0;
|
}
|
finalBlock.putInt32(bits);
|
|
var s2 = {
|
h0: _state.h0,
|
h1: _state.h1,
|
h2: _state.h2,
|
h3: _state.h3,
|
h4: _state.h4,
|
h5: _state.h5,
|
h6: _state.h6,
|
h7: _state.h7
|
};
|
_update(s2, _w, finalBlock);
|
var rval = forge.util.createBuffer();
|
rval.putInt32(s2.h0);
|
rval.putInt32(s2.h1);
|
rval.putInt32(s2.h2);
|
rval.putInt32(s2.h3);
|
rval.putInt32(s2.h4);
|
rval.putInt32(s2.h5);
|
rval.putInt32(s2.h6);
|
rval.putInt32(s2.h7);
|
return rval;
|
};
|
|
return md;
|
};
|
|
// sha-256 padding bytes not initialized yet
|
var _padding = null;
|
var _initialized = false;
|
|
// table of constants
|
var _k = null;
|
|
/**
|
* Initializes the constant tables.
|
*/
|
function _init() {
|
// create padding
|
_padding = String.fromCharCode(128);
|
_padding += forge.util.fillString(String.fromCharCode(0x00), 64);
|
|
// create K table for SHA-256
|
_k = [
|
0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
|
0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
|
0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
|
0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
|
0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
|
0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
|
0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
|
0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
|
0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
|
0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
|
0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
|
0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
|
0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
|
0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
|
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
|
0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2];
|
|
// now initialized
|
_initialized = true;
|
}
|
|
/**
|
* Updates a SHA-256 state with the given byte buffer.
|
*
|
* @param s the SHA-256 state to update.
|
* @param w the array to use to store words.
|
* @param bytes the byte buffer to update with.
|
*/
|
function _update(s, w, bytes) {
|
// consume 512 bit (64 byte) chunks
|
var t1, t2, s0, s1, ch, maj, i, a, b, c, d, e, f, g, h;
|
var len = bytes.length();
|
while(len >= 64) {
|
// the w array will be populated with sixteen 32-bit big-endian words
|
// and then extended into 64 32-bit words according to SHA-256
|
for(i = 0; i < 16; ++i) {
|
w[i] = bytes.getInt32();
|
}
|
for(; i < 64; ++i) {
|
// XOR word 2 words ago rot right 17, rot right 19, shft right 10
|
t1 = w[i - 2];
|
t1 =
|
((t1 >>> 17) | (t1 << 15)) ^
|
((t1 >>> 19) | (t1 << 13)) ^
|
(t1 >>> 10);
|
// XOR word 15 words ago rot right 7, rot right 18, shft right 3
|
t2 = w[i - 15];
|
t2 =
|
((t2 >>> 7) | (t2 << 25)) ^
|
((t2 >>> 18) | (t2 << 14)) ^
|
(t2 >>> 3);
|
// sum(t1, word 7 ago, t2, word 16 ago) modulo 2^32
|
w[i] = (t1 + w[i - 7] + t2 + w[i - 16]) | 0;
|
}
|
|
// initialize hash value for this chunk
|
a = s.h0;
|
b = s.h1;
|
c = s.h2;
|
d = s.h3;
|
e = s.h4;
|
f = s.h5;
|
g = s.h6;
|
h = s.h7;
|
|
// round function
|
for(i = 0; i < 64; ++i) {
|
// Sum1(e)
|
s1 =
|
((e >>> 6) | (e << 26)) ^
|
((e >>> 11) | (e << 21)) ^
|
((e >>> 25) | (e << 7));
|
// Ch(e, f, g) (optimized the same way as SHA-1)
|
ch = g ^ (e & (f ^ g));
|
// Sum0(a)
|
s0 =
|
((a >>> 2) | (a << 30)) ^
|
((a >>> 13) | (a << 19)) ^
|
((a >>> 22) | (a << 10));
|
// Maj(a, b, c) (optimized the same way as SHA-1)
|
maj = (a & b) | (c & (a ^ b));
|
|
// main algorithm
|
t1 = h + s1 + ch + _k[i] + w[i];
|
t2 = s0 + maj;
|
h = g;
|
g = f;
|
f = e;
|
// `>>> 0` necessary to avoid iOS/Safari 10 optimization bug
|
// can't truncate with `| 0`
|
e = (d + t1) >>> 0;
|
d = c;
|
c = b;
|
b = a;
|
// `>>> 0` necessary to avoid iOS/Safari 10 optimization bug
|
// can't truncate with `| 0`
|
a = (t1 + t2) >>> 0;
|
}
|
|
// update hash state
|
s.h0 = (s.h0 + a) | 0;
|
s.h1 = (s.h1 + b) | 0;
|
s.h2 = (s.h2 + c) | 0;
|
s.h3 = (s.h3 + d) | 0;
|
s.h4 = (s.h4 + e) | 0;
|
s.h5 = (s.h5 + f) | 0;
|
s.h6 = (s.h6 + g) | 0;
|
s.h7 = (s.h7 + h) | 0;
|
len -= 64;
|
}
|
}
|
