Category

Development Platform
Home > SourceCode/Document > Crypt_Decrypt algrithms > CA program > View Code
CDigest.java
Package: security.rar　[view]
Upload User: lior1029
Upload Date: 2013-05-07
Package Size: 209k
Code Size: 2k
Category:

CA program

Development Platform:

Java

CDigest.java：Code Content
  1. package org.infosecurity.cryptography;
  2. import org.infosecurity.cryptography.*;
  3. /**
  4.  * <p>Title: 摘要算法的抽象类 </p>
  5.  * <p>Description: 摘要算法的抽象类 </p>
  6.  * <p>Copyright: Copyright (c) 2003</p>
  7.  * <p>Company:bouncycastle org </p>
  8.  */
  9. public abstract class CDigest
  10.     implements IDigest
  11. {
  12.     private byte[]  xBuf;
  13.     private int     xBufOff;
  15.     private long    byteCount;
  16.     // 1.构造
  17. protected CDigest()
  18. {
  19. xBuf = new byte[4];
  20. xBufOff = 0;
  21. }
  22. protected CDigest(CDigest t)
  23. {
  24.         xBuf = new byte[t.xBuf.length];
  25. System.arraycopy(t.xBuf, 0, xBuf, 0, t.xBuf.length);
  27. xBufOff = t.xBufOff;
  28. byteCount = t.byteCount;
  29. }
  31.     // 2.输入一个字节的数据
  33.     public void update(
  34.         byte in)
  35.     {
  36.         xBuf[xBufOff++] = in;
  37.         // 填充满一个4个字节了
  38.         if (xBufOff == xBuf.length)
  39.         {
  40.             processWord(xBuf, 0);
  41.             xBufOff = 0;
  42.         }
  44.         byteCount++;
  45.     }
  47.     public void update(
  48.         byte[]  in,
  49.         int     inOff,
  50.         int     len)
  51.     {
  52.         //
  53.         // fill the current word
  54.         //
  55.         while ((xBufOff != 0) && (len > 0))
  56.         {
  57.             update(in[inOff]);
  59.             inOff++;
  60.             len--;
  61.         }
  63.         //
  64.         // process whole words.
  65.         //
  66.         while (len > xBuf.length)
  67.         {
  68.             processWord(in, inOff);
  70.             inOff += xBuf.length;
  71.             len -= xBuf.length;
  72.             byteCount += xBuf.length;
  73.         }
  75.         //
  76.         // load in the remainder.
  77.         //
  78.         while (len > 0)
  79.         {
  80.             update(in[inOff]);
  82.             inOff++;
  83.             len--;
  84.         }
  85.     }
  86.     // 3.完成
  87.     public void finish()
  88.     {
  89.         // 每一个字节是8位
  91.         long    bitLength = (byteCount << 3);
  93.         //
  94.         // 附加填充比特一个1，多个0，直到len mod 512 = 448
  95.         //1000,0000B=128
  96.         update((byte)128);
  98.         while (xBufOff != 0)
  99.         {
  100.             update((byte)0);
  101.         }
  102.         // 最后填充8字节(64bit)的长度信息
  103.         processLength(bitLength);
  104.         // 处理最后一块
  105.         processBlock();
  106.     }
  108.     public void reset()
  109.     {
  110.         byteCount = 0;
  112.         xBufOff = 0;
  113. for ( int i = 0; i < xBuf.length; i++ ) {
  114. xBuf[i] = 0;
  115. }
  116.     }
  118.     protected abstract void processWord(byte[] in, int inOff);
  120.     protected abstract void processLength(long bitLength);
  122.     protected abstract void processBlock();
  123. }