FileDocCategorySizeDatePackage
SHA256Digest.javaAPI DocAndroid 1.5 API7048Wed May 06 22:41:06 BST 2009org.bouncycastle.crypto.digests

SHA256Digest

public class SHA256Digest extends org.bouncycastle.crypto.digests.GeneralDigest
FIPS 180-2 implementation of SHA-256. 
block word digest
SHA-1 512 32 160
SHA-256 512 32 256
SHA-384 1024 64 384
SHA-512 1024 64 512

Fields Summary
private static final int
DIGEST_LENGTH
private int
H1
private int
H2
private int
H3
private int
H4
private int
H5
private int
H6
private int
H7
private int
H8
private int[]
X
private int
xOff
static final int[]
K
Constructors Summary
public SHA256Digest()
Standard constructor


           
     
    
        reset();
public SHA256Digest(SHA256Digest t)
Copy constructor. This will copy the state of the provided message digest.

        super(t);

        H1 = t.H1;
        H2 = t.H2;
        H3 = t.H3;
        H4 = t.H4;
        H5 = t.H5;
        H6 = t.H6;
        H7 = t.H7;
        H8 = t.H8;

        System.arraycopy(t.X, 0, X, 0, t.X.length);
        xOff = t.xOff;
Methods Summary
private intCh(int x, int y, int z)

        return (x & y) ^ ((~x) & z);
private intMaj(int x, int y, int z)

        return (x & y) ^ (x & z) ^ (y & z);
private intSum0(int x)

        return ((x >>> 2) | (x << 30)) ^ ((x >>> 13) | (x << 19)) ^ ((x >>> 22) | (x << 10));
private intSum1(int x)

        return ((x >>> 6) | (x << 26)) ^ ((x >>> 11) | (x << 21)) ^ ((x >>> 25) | (x << 7));
private intTheta0(int x)

        return ((x >>> 7) | (x << 25)) ^ ((x >>> 18) | (x << 14)) ^ (x >>> 3);
private intTheta1(int x)

        return ((x >>> 17) | (x << 15)) ^ ((x >>> 19) | (x << 13)) ^ (x >>> 10);
public intdoFinal(byte[] out, int outOff)

        finish();

        unpackWord(H1, out, outOff);
        unpackWord(H2, out, outOff + 4);
        unpackWord(H3, out, outOff + 8);
        unpackWord(H4, out, outOff + 12);
        unpackWord(H5, out, outOff + 16);
        unpackWord(H6, out, outOff + 20);
        unpackWord(H7, out, outOff + 24);
        unpackWord(H8, out, outOff + 28);

        reset();

        return DIGEST_LENGTH;
public java.lang.StringgetAlgorithmName()

        return "SHA-256";
public intgetDigestSize()

        return DIGEST_LENGTH;
protected voidprocessBlock()

        //
        // expand 16 word block into 64 word blocks.
        //
        for (int t = 16; t <= 63; t++)
        {
            X[t] = Theta1(X[t - 2]) + X[t - 7] + Theta0(X[t - 15]) + X[t - 16];
        }

        //
        // set up working variables.
        //
        int     a = H1;
        int     b = H2;
        int     c = H3;
        int     d = H4;
        int     e = H5;
        int     f = H6;
        int     g = H7;
        int     h = H8;

        int t = 0;     
        for(int i = 0; i < 8; i ++)
        {
            // t = 8 * i
            h += Sum1(e) + Ch(e, f, g) + K[t] + X[t++];
            d += h;
            h += Sum0(a) + Maj(a, b, c);

            // t = 8 * i + 1
            g += Sum1(d) + Ch(d, e, f) + K[t] + X[t++];
            c += g;
            g += Sum0(h) + Maj(h, a, b);

            // t = 8 * i + 2
            f += Sum1(c) + Ch(c, d, e) + K[t] + X[t++];
            b += f;
            f += Sum0(g) + Maj(g, h, a);

            // t = 8 * i + 3
            e += Sum1(b) + Ch(b, c, d) + K[t] + X[t++];
            a += e;
            e += Sum0(f) + Maj(f, g, h);

            // t = 8 * i + 4
            d += Sum1(a) + Ch(a, b, c) + K[t] + X[t++];
            h += d;
            d += Sum0(e) + Maj(e, f, g);

            // t = 8 * i + 5
            c += Sum1(h) + Ch(h, a, b) + K[t] + X[t++];
            g += c;
            c += Sum0(d) + Maj(d, e, f);

            // t = 8 * i + 6
            b += Sum1(g) + Ch(g, h, a) + K[t] + X[t++];
            f += b;
            b += Sum0(c) + Maj(c, d, e);

            // t = 8 * i + 7
            a += Sum1(f) + Ch(f, g, h) + K[t] + X[t++];
            e += a;
            a += Sum0(b) + Maj(b, c, d);
        }

        H1 += a;
        H2 += b;
        H3 += c;
        H4 += d;
        H5 += e;
        H6 += f;
        H7 += g;
        H8 += h;

        //
        // reset the offset and clean out the word buffer.
        //
        xOff = 0;
        for (int i = 0; i < 16; i++)
        {
            X[i] = 0;
        }
protected voidprocessLength(long bitLength)

        if (xOff > 14)
        {
            processBlock();
        }

        X[14] = (int)(bitLength >>> 32);
        X[15] = (int)(bitLength & 0xffffffff);
protected voidprocessWord(byte[] in, int inOff)

        X[xOff++] = ((in[inOff] & 0xff) << 24) | ((in[inOff + 1] & 0xff) << 16)
                    | ((in[inOff + 2] & 0xff) << 8) | ((in[inOff + 3] & 0xff)); 

        if (xOff == 16)
        {
            processBlock();
        }
public voidreset()
reset the chaining variables

        super.reset();

        /* SHA-256 initial hash value
         * The first 32 bits of the fractional parts of the square roots
         * of the first eight prime numbers
         */

        H1 = 0x6a09e667;
        H2 = 0xbb67ae85;
        H3 = 0x3c6ef372;
        H4 = 0xa54ff53a;
        H5 = 0x510e527f;
        H6 = 0x9b05688c;
        H7 = 0x1f83d9ab;
        H8 = 0x5be0cd19;

        xOff = 0;
        for (int i = 0; i != X.length; i++)
        {
            X[i] = 0;
        }
private voidunpackWord(int word, byte[] out, int outOff)

        out[outOff]     = (byte)(word >>> 24);
        out[outOff + 1] = (byte)(word >>> 16);
        out[outOff + 2] = (byte)(word >>> 8);
        out[outOff + 3] = (byte)word;