用vb实现DES加解密算法(三)--解密

用vb实现DES加解密算法(三)--解密(31)         S(5) = S6(CodeS6(5) + CodeS6(0) * 2, CodeS6(4) + CodeS6(3) * 2 + CodeS6(2) * 4 + CodeS6(1) * 8)
        S(6) = S7(CodeS7(5) + CodeS7(0) * 2, CodeS7(4) + CodeS7(3) * 2 + CodeS7(2) * 4 + CodeS7(1) * 8)
        S(7) = S8(CodeS8(5) + CodeS8(0) * 2, CodeS8(4) + CodeS8(3) * 2 + CodeS8(2) * 4 + CodeS8(1) * 8)
   
    'S盒运算32位结果
    For i = 0 To 7
        RetS(i * 4 + 0) = (S(i) And &H8) \ &H8
        RetS(i * 4 + 1) = (S(i) And &H4) \ &H4
        RetS(i * 4 + 2) = (S(i) And &H2) \ &H2
        RetS(i * 4 + 3) = (S(i) And &H1) \ &H1
    Next
   
   
    For i = 0 To 31
        'P变换
        CodeP(i) = RetS(P(i))
       
        '产生L12,R12
        R12(i) = L11(i) Xor CodeP(i)
        L12(i) = R11(i)
    Next
   
    '进行第13次迭代
    For i = 0 To 47
        CodeE(i) = R12(E(i))                 '经过E变换扩充，由32位变为48位
        CodeE(i) = CodeE(i) Xor K4(i)        '与K4按位作不进位加法运算
    Next
   
    '分8组
    For i = 0 To 5
        CodeS1(i) = CodeE(i)
        CodeS2(i) = CodeE(i + 6)