package com.security;

import org.bouncycastle.util.encoders.Hex;


public class SM3Digest{
	/** SM3值的长度 */
    private static final int BYTE_LENGTH = 32;

    /** SM3分组长度 */
    private static final int BLOCK_LENGTH = 64;

    /** 缓冲区长度 */
    private static final int BUFFER_LENGTH = BLOCK_LENGTH * 1;

    /** 缓冲区 */
    private byte[] xBuf = new byte[BUFFER_LENGTH];

    /** 缓冲区偏移量 */
    private int xBufOff;

    /** 初始向量 */
    private byte[] V = SM3.iv.clone();

    private int cntBlock = 0;

    public SM3Digest() {
    }

    public SM3Digest(SM3Digest t){
        System.arraycopy(t.xBuf, 0, this.xBuf, 0, t.xBuf.length);
        this.xBufOff = t.xBufOff;
        System.arraycopy(t.V, 0, this.V, 0, t.V.length);
    }

    /**
     * SM3结果输出
     *
     * @param out 保存SM3结构的缓冲区
     * @param outOff 缓冲区偏移量
     * @return
     */
    public int doFinal(byte[] out, int outOff){
        byte[] tmp = doFinal();
        System.arraycopy(tmp, 0, out, 0, tmp.length);
        return BYTE_LENGTH;
    }

    public void reset(){
        xBufOff = 0;
        cntBlock = 0;
        V = SM3.iv.clone();
    }

    /**
     * 明文输入
     *
     * @param in
     *            明文输入缓冲区
     * @param inOff
     *            缓冲区偏移量
     * @param len
     *            明文长度
     */
    public void update(byte[] in, int inOff, int len){
        int partLen = BUFFER_LENGTH - xBufOff;
        int inputLen = len;
        int dPos = inOff;
        if (partLen < inputLen){
            System.arraycopy(in, dPos, xBuf, xBufOff, partLen);
            inputLen -= partLen;
            dPos += partLen;
            doUpdate();
            while (inputLen > BUFFER_LENGTH){
                System.arraycopy(in, dPos, xBuf, 0, BUFFER_LENGTH);
                inputLen -= BUFFER_LENGTH;
                dPos += BUFFER_LENGTH;
                doUpdate();
            }
        }

        System.arraycopy(in, dPos, xBuf, xBufOff, inputLen);
        xBufOff += inputLen;
    }

    private void doUpdate(){
        byte[] B = new byte[BLOCK_LENGTH];
        for (int i = 0; i < BUFFER_LENGTH; i += BLOCK_LENGTH){
            System.arraycopy(xBuf, i, B, 0, B.length);
            doHash(B);
        }
        xBufOff = 0;
    }

    private void doHash(byte[] B){
        byte[] tmp = SM3.CF(V, B);
        System.arraycopy(tmp, 0, V, 0, V.length);
        cntBlock++;
    }

    private byte[] doFinal(){
        byte[] B = new byte[BLOCK_LENGTH];
        byte[] buffer = new byte[xBufOff];
        System.arraycopy(xBuf, 0, buffer, 0, buffer.length);
        byte[] tmp = SM3.padding(buffer, cntBlock);
        for (int i = 0; i < tmp.length; i += BLOCK_LENGTH)
        {
            System.arraycopy(tmp, i, B, 0, B.length);
            doHash(B);
        }
        return V;
    }

    public void update(byte in){
        byte[] buffer = new byte[] { in };
        update(buffer, 0, 1);
    }

    public int getDigestSize(){
        return BYTE_LENGTH;
    }
	
	
}
