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用vb实现DES加解密算法(三)--解密 |
热 ★★★★ |
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用vb实现DES加解密算法(三)--解密 |
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作者：闵涛 文章来源：闵涛的学习笔记 点击数：3941 更新时间：2009/4/23 18:59:36  |
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8(i) = R7(i)
Next
''''进行第9次迭代
For i = 0 To 47
CodeE(i) = R8(E(i)) ''''经过E变换扩充，由32位变为48位
CodeE(i) = CodeE(i) Xor K8(i) ''''与K8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)
CodeS3(i) = CodeE(i + 12)
CodeS4(i) = CodeE(i + 18)
CodeS5(i) = CodeE(i + 24)
CodeS6(i) = CodeE(i + 30)
CodeS7(i) = CodeE(i + 36)
CodeS8(i) = CodeE(i + 42)
Next
''''S盒运算，得到8个数
S(0) = S1(CodeS1(5) + CodeS1(0) * 2, CodeS1(4) + CodeS1(3) * 2 + CodeS1(2) * 4 + CodeS1(1) * 8)
S(1) = S2(CodeS2(5) + CodeS2(0) * 2, CodeS2(4) + CodeS2(3) * 2 + CodeS2(2) * 4 + CodeS2(1) * 8)
S(2) = S3(CodeS3(5) + CodeS3(0) * 2, CodeS3(4) + CodeS3(3) * 2 + CodeS3(2) * 4 + CodeS3(1) * 8)
S(3) = S4(CodeS4(5) + CodeS4(0) * 2, CodeS4(4) + CodeS4(3) * 2 + CodeS4(2) * 4 + CodeS4(1) * 8)
S(4) = S5(CodeS5(5) + CodeS5(0) * 2, CodeS5(4) + CodeS5(3) * 2 + CodeS5(2) * 4 + CodeS5(1) * 8)
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L9,R9
R9(i) = L8(i) Xor CodeP(i)
L9(i) = R8(i)
Next
''''进行第10次迭代
For i = 0 To 47
CodeE(i) = R9(E(i)) ''''经过E变换扩充，由32位变为48位
CodeE(i) = CodeE(i) Xor K7(i) ''''与K7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)
CodeS3(i) = CodeE(i + 12)
CodeS4(i) = CodeE(i + 18)
CodeS5(i) = CodeE(i + 24)
CodeS6(i) = CodeE(i + 30)
CodeS7(i) = CodeE(i + 36)
CodeS8(i) = CodeE(i + 42)
Next
''''S盒运算，得到8个数
S(0) = S1(CodeS1(5) + CodeS1(0) * 2, CodeS1(4) + CodeS1(3) * 2 + CodeS1(2) * 4 + CodeS1(1) * 8)
S(1) = S2(CodeS2(5) + CodeS2(0) * 2, CodeS2(4) + CodeS2(3) * 2 + CodeS2(2) * 4 + CodeS2(1) * 8)
S(2) = S3(CodeS3(5) + CodeS3(0) * 2, CodeS3(4) + CodeS3(3) * 2 + CodeS3(2) * 4 + CodeS3(1) * 8)
S(3) = S4(CodeS4(5) + CodeS4(0) * 2, CodeS4(4) + CodeS4(3) * 2 + CodeS4(2) * 4 + CodeS4(1) * 8)
S(4) = S5(CodeS5(5) + CodeS5(0) * 2, CodeS5(4) + CodeS5(3) * 2 + CodeS5(2) * 4 + CodeS5(1) * 8)
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L10,R10
R10(i) = L9(i) Xor CodeP(i)
L10(i) = R9(i)
Next
''''进行第11次迭代
For i = 0 To 47
CodeE(i) = R10(E(i)) ''''经过E变换扩充，由32位变为48位
CodeE(i) = CodeE(i) Xor K6(i) ''''与K6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)
CodeS3(i) = CodeE(i + 12)
CodeS4(i) = CodeE(i + 18)
CodeS5(i) = CodeE(i + 24)
CodeS6(i) = CodeE(i + 30)
CodeS7(i) = CodeE(i + 36)
CodeS8(i) = CodeE(i + 42)
Next
''''S盒运算，得到8个数
S(0) = S1(CodeS1(5) + CodeS1(0) * 2, CodeS1(4) + CodeS1(3) * 2 + CodeS1(2) * 4 + CodeS1(1) * 8)
S(1) = S2(CodeS2(5) + CodeS2(0) * 2, CodeS2(4) + CodeS2(3) * 2 + CodeS2(2) * 4 + CodeS2(1) * 8)
S(2) = S3(CodeS3(5) + CodeS3(0) * 2, CodeS3(4) + CodeS3(3) * 2 + CodeS3(2) * 4 + CodeS3(1) * 8)
S(3) = S4(CodeS4(5) + CodeS4(0) * 2, CodeS4(4) + CodeS4(3) * 2 + CodeS4(2) * 4 + CodeS4(1) * 8)
S(4) = S5(CodeS5(5) + CodeS5(0) * 2, CodeS5(4) + CodeS5(3) * 2 + CodeS5(2) * 4 + CodeS5(1) * 8)
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L11,R11
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