函数H是逐位奇偶操作符。假设Mj表示消息的第j个子分组(从0到15),常数ti是4294967296*abs( sin(i) )的整数部分,i 取值从1到64,单位是弧度。(4294967296=2)现定义:FF(a ,b ,c ,d ,Mj ,s ,ti ) 操作为 a = b + ( (a + F(b,c,d) + Mj + ti) << s)GG(a ,b ,c ,d ,Mj ,s ,ti ) 操作为 a = b + ( (a + G(b,c,d) + Mj + ti) << s)HH(a ,b ,c ,d ,Mj ,s ,ti) 操作为 a = b + ( (a + H(b,c,d) + Mj + ti) << s)II(a ,b ,c ,d ,Mj ,s ,ti) 操作为 a = b + ( (a + I(b,c,d) + Mj + ti) << s)注意:“<<”表示循环左移位,不是左移位。这四轮(共64步)是:第一轮FF(a ,b ,c ,d ,M0 ,7 ,0xd76aa478 )FF(d ,a ,b ,c ,M1 ,12 ,0xe8c7b756 )FF(c ,d ,a ,b ,M2 ,17 ,0x242070db )FF(b ,c ,d ,a ,M3 ,22 ,0xc1bdceee )FF(a ,b ,c ,d ,M4 ,7 ,0xf57c0faf )FF(d ,a ,b ,c ,M5 ,12 ,0x4787c62a )FF(c ,d ,a ,b ,M6 ,17 ,0xa8304613 )FF(b ,c ,d ,a ,M7 ,22 ,0xfd469501)FF(a ,b ,c ,d ,M8 ,7 ,0x698098d8 )FF(d ,a ,b ,c ,M9 ,12 ,0x8b44f7af )FF(c ,d ,a ,b ,M10 ,17 ,0xffff5bb1 )FF(b ,c ,d ,a ,M11 ,22 ,0x895cd7be )FF(a ,b ,c ,d ,M12 ,7 ,0x6b901122 )FF(d ,a ,b ,c ,M13 ,12 ,0xfd987193 )FF(c ,d ,a ,b ,M14 ,17 ,0xa679438e )FF(b ,c ,d ,a ,M15 ,22 ,0x49b40821 )第二轮GG(a ,b ,c ,d ,M1 ,5 ,0xf61e2562 )GG(d ,a ,b ,c ,M6 ,9 ,0xc040b340 )GG(c ,d ,a ,b ,M11 ,14 ,0x265e5a51 )GG(b ,c ,d ,a ,M0 ,20 ,0xe9b6c7aa )GG(a ,b ,c ,d ,M5 ,5 ,0xd62f105d )GG(d ,a ,b ,c ,M10 ,9 ,0x02441453 )GG(c ,d ,a ,b ,M15 ,14 ,0xd8a1e681 )GG(b ,c ,d ,a ,M4 ,20 ,0xe7d3fbc8 )GG(a ,b ,c ,d ,M9 ,5 ,0x21e1cde6 )GG(d ,a ,b ,c ,M14 ,9 ,0xc33707d6 )GG(c ,d ,a ,b ,M3 ,14 ,0xf4d50d87 )GG(b ,c ,d ,a ,M8 ,20 ,0x455a14ed )GG(a ,b ,c ,d ,M13 ,5 ,0xa9e3e905 )GG(d ,a ,b ,c ,M2 ,9 ,0xfcefa3f8 )GG(c ,d ,a ,b ,M7 ,14 ,0x676f02d9 )GG(b ,c ,d ,a ,M12 ,20 ,0x8d2a4c8a )第三轮HH(a ,b ,c ,d ,M5 ,4 ,0xfffa3942 )HH(d ,a ,b ,c ,M8 ,11 ,0x8771f681 )HH(c ,d ,a ,b ,M11 ,16 ,0x6d9d6122 )HH(b ,c ,d ,a ,M14 ,23 ,0xfde5380c )HH(a ,b ,c ,d ,M1 ,4 ,0xa4beea44 )HH(d ,a ,b ,c ,M4 ,11 ,0x4bdecfa9 )HH(c ,d ,a ,b ,M7 ,16 ,0xf6bb4b60 )HH(b ,c ,d ,a ,M10 ,23 ,0xbebfbc70 )HH(a ,b ,c ,d ,M13 ,4 ,0x289b7ec6 )HH(d ,a ,b ,c ,M0 ,11 ,0xeaa127fa )HH(c ,d ,a ,b ,M3 ,16 ,0xd4ef3085 )HH(b ,c ,d ,a ,M6 ,23 ,0x04881d05 )HH(a ,b ,c ,d ,M9 ,4 ,0xd9d4d039 )HH(d ,a ,b ,c ,M12 ,11 ,0xe6db99e5 )HH(c ,d ,a ,b ,M15 ,16 ,0x1fa27cf8 )HH(b ,c ,d ,a ,M2 ,23 ,0xc4ac5665 )第四轮II(a ,b ,c ,d ,M0 ,6 ,0xf4292244 )II(d ,a ,b ,c ,M7 ,10 ,0x432aff97 )II(c ,d ,a ,b ,M14 ,15 ,0xab9423a7 )II(b ,c ,d ,a ,M5 ,21 ,0xfc93a039 )II(a ,b ,c ,d ,M12 ,6 ,0x655b59c3 )II(d ,a ,b ,c ,M3 ,10 ,0x8f0ccc92 )II(c ,d ,a ,b ,M10 ,15 ,0xffeff47d )II(b ,c ,d ,a ,M1 ,21 ,0x85845dd1 )II(a ,b ,c ,d ,M8 ,6 ,0x6fa87e4f )II(d ,a ,b ,c ,M15 ,10 ,0xfe2ce6e0 )II(c ,d ,a ,b ,M6 ,15 ,0xa3014314 )II(b ,c ,d ,a ,M13 ,21 ,0x4e0811a1 )II(a ,b ,c ,d ,M4 ,6 ,0xf7537e82 )II(d ,a ,b ,c ,M11 ,10 ,0xbd3af235 )II(c ,d ,a ,b ,M2 ,15 ,0x2ad7d2bb )II(b ,c ,d ,a ,M9 ,21 ,0xeb86d391 )