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/*
* File: SHA256Hash.java
* Authors: Kevin R. Dixon
* Company: Sandia National Laboratories
* Project: Cognitive Foundry
*
* Copyright Feb 7, 2011, Sandia Corporation.
* Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
* license for use of this work by or on behalf of the U.S. Government.
* Export of this program may require a license from the United States
* Government. See CopyrightHistory.txt for complete details.
*
*/
package gov.sandia.cognition.hash;
import gov.sandia.cognition.annotation.PublicationReference;
import gov.sandia.cognition.annotation.PublicationType;
import gov.sandia.cognition.util.ObjectUtil;
import java.util.Arrays;
/**
* The SHA-2, 256-bit (32 byte) hash function.
* @author Kevin R. Dixon
* @since 3.4.2
*/
@PublicationReference(
author="Wikipedia",
title="SHA-2",
type=PublicationType.WebPage,
year=2011,
url="http://en.wikipedia.org/wiki/SHA-2"
)
public class SHA256Hash
extends AbstractHashFunction
{
/**
* Length of the hash is 256 bits (32 bytes), {@value}.
*/
public static final int LENGTH = 32;
/**
* Length of the hash block is 512 bits (64 bytes), {@value}.
*/
public static final int BLOCK_SIZE = 64;
/**
* Default seed
*/
protected static final byte[] DEFAULT_SEED = {
(byte)0x6a, (byte)0x09, (byte)0xe6, (byte)0x67,
(byte)0xbb, (byte)0x67, (byte)0xae, (byte)0x85,
(byte)0x3c, (byte)0x6e, (byte)0xf3, (byte)0x72,
(byte)0xa5, (byte)0x4f, (byte)0xf5, (byte)0x3a,
(byte)0x51, (byte)0x0e, (byte)0x52, (byte)0x7f,
(byte)0x9b, (byte)0x05, (byte)0x68, (byte)0x8c,
(byte)0x1f, (byte)0x83, (byte)0xd9, (byte)0xab,
(byte)0x5b, (byte)0xe0, (byte)0xcd, (byte)0x19
};
/**
* Round constants
*/
private static final int 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
};
/**
* Default constructor
*/
public SHA256Hash()
{
super();
}
@Override
public SHA256Hash clone()
{
return (SHA256Hash) super.clone();
}
@Override
public int length()
{
return LENGTH;
}
@Override
public void evaluateInto(
byte[] input,
byte[] output,
byte[] seed)
{
if( seed.length != LENGTH )
{
throw new IllegalArgumentException(
"Expected seed to be of length " + LENGTH );
}
hash( input, output, seed );
}
/**
* SHA-2 256-bit hash function
* @param input
* Input to hash
* @return
* Output to store the hash
*/
public static byte[] hash(
byte[] input )
{
byte[] output = new byte[ LENGTH ];
hash( input, output );
return output;
}
/**
* SHA-2 256-bit hash function
* @param input
* Input to hash
* @param output
* Output to store the hash
*/
public static void hash(
byte[] input,
byte[] output )
{
hash( input, output, DEFAULT_SEED );
}
/**
* SHA-2 256-bit hash function
* @param input
* Input to hash
* @param output
* Output to store the hash
* @param seed
* Seed values
*/
public static void hash(
byte[] input,
byte[] output,
byte[] seed )
{
if( output.length != LENGTH )
{
throw new IllegalArgumentException(
"Expected output to be of length " + LENGTH );
}
if( seed.length != LENGTH )
{
throw new IllegalArgumentException(
"Expected seed to be of length: " + LENGTH );
}
if( input == null )
{
Arrays.fill(output, (byte) 0 );
return;
}
// The way padMessage works, paddedLength will be an even multiple
// of 64-bytes (512-bits)
final byte[] paddedInput = padMessage(input);
final int paddedLength = paddedInput.length;
final int numBlocks = paddedLength / BLOCK_SIZE;
// The "h" variables store the hash
int h0 = HashFunctionUtil.toInteger( seed, 0*4 );
int h1 = HashFunctionUtil.toInteger( seed, 1*4 );
int h2 = HashFunctionUtil.toInteger( seed, 2*4 );
int h3 = HashFunctionUtil.toInteger( seed, 3*4 );
int h4 = HashFunctionUtil.toInteger( seed, 4*4 );
int h5 = HashFunctionUtil.toInteger( seed, 5*4 );
int h6 = HashFunctionUtil.toInteger( seed, 6*4 );
int h7 = HashFunctionUtil.toInteger( seed, 7*4 );
final int[] w = new int[ BLOCK_SIZE ];
final int wlength = w.length;
int index = 0;
for( int block = 0; block < numBlocks; block++ )
{
// Convert this 64-byte (512-bit) block into 16 4-byte (32-bit) ints
for( int i = 0; i < 16; i++ )
{
w[i] = ((paddedInput[index++] & 0xff) << 24)
| ((paddedInput[index++] & 0xff) << 16)
| ((paddedInput[index++] & 0xff) << 8)
| ((paddedInput[index++] & 0xff) );
}
// This spawns words 16..63 in the block
for( int i = 16; i < wlength; i++ )
{
final int wim15 = w[i-15];
final int wim2 = w[i-2];
final int s0 = Integer.rotateRight(wim15, 7) ^ Integer.rotateRight(wim15,18) ^ (wim15 >>> 3);
final int s1 = Integer.rotateRight(wim2, 17) ^ Integer.rotateRight(wim2, 19) ^ (wim2 >>> 10);
w[i] = w[i-16] + s0 + w[i-7] + s1;
}
int a = h0;
int b = h1;
int c = h2;
int d = h3;
int e = h4;
int f = h5;
int g = h6;
int h = h7;
// Run 64 rounds of the SHA2 loop for this block
for( int round = 0; round < 64; round++ )
{
int s0 = Integer.rotateRight(a,2) ^ Integer.rotateRight(a,13) ^ Integer.rotateRight(a,22);
int maj = (a & b) ^ (a & c) ^ (b & c);
int t2 = s0 + maj;
int s1 = Integer.rotateRight(e,6) ^ Integer.rotateRight(e,11) ^ Integer.rotateRight(e,25);
int ch = (e & f) ^ ((~e) & g);
int t1 = h + s1 + ch + K[round] + w[round];
h = g;
g = f;
f = e;
e = d + t1;
d = c;
c = b;
b = a;
a = t1 + t2;
}
h0 += a;
h1 += b;
h2 += c;
h3 += d;
h4 += e;
h5 += f;
h6 += g;
h7 += h;
}
byte[] word = new byte[ 4 ];
HashFunctionUtil.toByteArray(h0, word );
System.arraycopy(word, 0, output, 0, word.length);
HashFunctionUtil.toByteArray(h1, word );
System.arraycopy(word, 0, output, 1*4, word.length);
HashFunctionUtil.toByteArray(h2, word );
System.arraycopy(word, 0, output, 2*4, word.length);
HashFunctionUtil.toByteArray(h3, word );
System.arraycopy(word, 0, output, 3*4, word.length);
HashFunctionUtil.toByteArray(h4, word );
System.arraycopy(word, 0, output, 4*4, word.length);
HashFunctionUtil.toByteArray(h5, word );
System.arraycopy(word, 0, output, 5*4, word.length);
HashFunctionUtil.toByteArray(h6, word );
System.arraycopy(word, 0, output, 6*4, word.length);
HashFunctionUtil.toByteArray(h7, word );
System.arraycopy(word, 0, output, 7*4, word.length);
}
/**
* Pads the given input message with the padding specified by the SHA-2
* standard
* @param input
* Input message to pad, unchanged.
* @return
* Padded input message, length will be an integer multiple of 64 bytes.
*/
private static byte[] padMessage(
byte[] input )
{
final int inputLength = input.length;
final int remainderLength = inputLength % BLOCK_SIZE;
// We have to append a '1' to the message, then "bunch of zeros",
// finally the original message length as a 64-bit (8-byte) big endian
// number. But the "bunch of zeros" is the number needed to make this
// an even 64-bit length...
// Confusing, eh?
int tailLength;
if( (BLOCK_SIZE - remainderLength) >= 9 )
{
tailLength = BLOCK_SIZE - remainderLength;
}
else
{
tailLength = 2*BLOCK_SIZE - remainderLength;
}
byte[] tail = new byte[ tailLength ];
// This will append a '1' to the end of the message
tail[0] = (byte) 0x80;
// This will shove the length in bits as a big-endian 64-bit number
// at the end of the block.
// Magically, the rest of the pad will be zeros.
final long lengthInBits = inputLength * 8;
tail[tailLength-9+1] = (byte)(lengthInBits >>> 56);
tail[tailLength-9+2] = (byte)(lengthInBits >>> 48);
tail[tailLength-9+3] = (byte)(lengthInBits >>> 40);
tail[tailLength-9+4] = (byte)(lengthInBits >>> 32);
tail[tailLength-9+5] = (byte)(lengthInBits >>> 24);
tail[tailLength-9+6] = (byte)(lengthInBits >>> 16);
tail[tailLength-9+7] = (byte)(lengthInBits >>> 8);
tail[tailLength-9+8] = (byte)(lengthInBits);
// Concatenate the original message with the tail block (or blocks)
byte[] paddedMessage = new byte[ inputLength + tailLength ];
System.arraycopy(input, 0, paddedMessage, 0, inputLength);
System.arraycopy(tail, 0, paddedMessage, inputLength, tailLength);
return paddedMessage;
}
@Override
public byte[] getDefaultSeed()
{
return ObjectUtil.deepCopy(DEFAULT_SEED);
}
}
