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SHA1Digest.javaAPI DocAndroid 1.5 API7000Wed May 06 22:41:06 BST 2009org.bouncycastle.crypto.digests

SHA1Digest

public class SHA1Digest extends GeneralDigest
implementation of SHA-1 as outlined in "Handbook of Applied Cryptography", pages 346 - 349. It is interesting to ponder why the, apart from the extra IV, the other difference here from MD5 is the "endienness" of the word processing!

(Omit source code)

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[]
X
private int
xOff
private static final int
Y1
private static final int
Y2
private static final int
Y3
private static final int
Y4
Constructors Summary
public SHA1Digest()
Standard constructor


           
     
    
        reset();
    
public SHA1Digest(SHA1Digest 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;

        System.arraycopy(t.X, 0, X, 0, t.X.length);
        xOff = t.xOff;
    
Methods Summary
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);

        reset();

        return DIGEST_LENGTH;
    
private intf(int u, int v, int w)

   
      
            
            
            
    
        return ((u & v) | ((~u) & w));
    
private intg(int u, int v, int w)

        return ((u & v) | (u & w) | (v & w));
    
public java.lang.StringgetAlgorithmName()

        return "SHA-1";
    
public intgetDigestSize()

        return DIGEST_LENGTH;
    
private inth(int u, int v, int w)

        return (u ^ v ^ w);
    
protected voidprocessBlock()

        //
        // expand 16 word block into 80 word block.
        //
        for (int i = 16; i < 80; i++)
        {
            int t = X[i - 3] ^ X[i - 8] ^ X[i - 14] ^ X[i - 16];
            X[i] = t << 1 | t >>> 31;
        }

        //
        // set up working variables.
        //
        int     A = H1;
        int     B = H2;
        int     C = H3;
        int     D = H4;
        int     E = H5;

        //
        // round 1
        //
        int idx = 0;
        
        for (int j = 0; j < 4; j++)
        {
            // E = rotateLeft(A, 5) + f(B, C, D) + E + X[idx++] + Y1
            // B = rotateLeft(B, 30)
            E += (A << 5 | A >>> 27) + f(B, C, D) + X[idx++] + Y1;
            B = B << 30 | B >>> 2;
        
            D += (E << 5 | E >>> 27) + f(A, B, C) + X[idx++] + Y1;
            A = A << 30 | A >>> 2;
       
            C += (D << 5 | D >>> 27) + f(E, A, B) + X[idx++] + Y1;
            E = E << 30 | E >>> 2;
       
            B += (C << 5 | C >>> 27) + f(D, E, A) + X[idx++] + Y1;
            D = D << 30 | D >>> 2;

            A += (B << 5 | B >>> 27) + f(C, D, E) + X[idx++] + Y1;
            C = C << 30 | C >>> 2;
        }
        
        //
        // round 2
        //
        for (int j = 0; j < 4; j++)
        {
            // E = rotateLeft(A, 5) + h(B, C, D) + E + X[idx++] + Y2
            // B = rotateLeft(B, 30)
            E += (A << 5 | A >>> 27) + h(B, C, D) + X[idx++] + Y2;
            B = B << 30 | B >>> 2;   
            
            D += (E << 5 | E >>> 27) + h(A, B, C) + X[idx++] + Y2;
            A = A << 30 | A >>> 2;
            
            C += (D << 5 | D >>> 27) + h(E, A, B) + X[idx++] + Y2;
            E = E << 30 | E >>> 2;
            
            B += (C << 5 | C >>> 27) + h(D, E, A) + X[idx++] + Y2;
            D = D << 30 | D >>> 2;

            A += (B << 5 | B >>> 27) + h(C, D, E) + X[idx++] + Y2;
            C = C << 30 | C >>> 2;
        }
        
        //
        // round 3
        //
        for (int j = 0; j < 4; j++)
        {
            // E = rotateLeft(A, 5) + g(B, C, D) + E + X[idx++] + Y3
            // B = rotateLeft(B, 30)
            E += (A << 5 | A >>> 27) + g(B, C, D) + X[idx++] + Y3;
            B = B << 30 | B >>> 2;
            
            D += (E << 5 | E >>> 27) + g(A, B, C) + X[idx++] + Y3;
            A = A << 30 | A >>> 2;
            
            C += (D << 5 | D >>> 27) + g(E, A, B) + X[idx++] + Y3;
            E = E << 30 | E >>> 2;
            
            B += (C << 5 | C >>> 27) + g(D, E, A) + X[idx++] + Y3;
            D = D << 30 | D >>> 2;

            A += (B << 5 | B >>> 27) + g(C, D, E) + X[idx++] + Y3;
            C = C << 30 | C >>> 2;
        }

        //
        // round 4
        //
        for (int j = 0; j <= 3; j++)
        {
            // E = rotateLeft(A, 5) + h(B, C, D) + E + X[idx++] + Y4
            // B = rotateLeft(B, 30)
            E += (A << 5 | A >>> 27) + h(B, C, D) + X[idx++] + Y4;
            B = B << 30 | B >>> 2;
            
            D += (E << 5 | E >>> 27) + h(A, B, C) + X[idx++] + Y4;
            A = A << 30 | A >>> 2;
            
            C += (D << 5 | D >>> 27) + h(E, A, B) + X[idx++] + Y4;
            E = E << 30 | E >>> 2;
            
            B += (C << 5 | C >>> 27) + h(D, E, A) + X[idx++] + Y4;
            D = D << 30 | D >>> 2;

            A += (B << 5 | B >>> 27) + h(C, D, E) + X[idx++] + Y4;
            C = C << 30 | C >>> 2;
        }


        H1 += A;
        H2 += B;
        H3 += C;
        H4 += D;
        H5 += E;

        //
        // reset start of the 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();

        H1 = 0x67452301;
        H2 = 0xefcdab89;
        H3 = 0x98badcfe;
        H4 = 0x10325476;
        H5 = 0xc3d2e1f0;

        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++] = (byte)(word >>> 16);
        out[outOff++] = (byte)(word >>> 8);
        out[outOff++] = (byte)word;