MD5算法的实现以及分析，主循环有四轮（MD4只有三轮），每轮循环都很相似。第一轮进行16次操作。每次操作对a、b、c和d中的其中三个作一次非线性函数运算，然后将所得结果加上第四个变量，文本的一个子分组和一个常数。再将所得结果向右环移一个不定的数，并加上a、b、c或d中之一。最后用该结果取代a、b、c或d中之一。-MD5 algorithm implementation and analysis, the main loop there are four rounds (MD4 only three), each round of circulation are very similar. The first round of the 16 operations. Each operation on a, b, c and d for the first time in three of the nonlinear function operation, then the result plus a fourth variable, the text of a sub-group, and a constant. The results then move to the right of a variable number of rings, plus a, b, c or d in one. Finally, the results of replacing a, b, c or d in one.