用vb实现DES加解密算法(三)--解密

'sCode 待解密字串

'sKey 密钥字串

Public Sub DES_Decode(ByRef sCode() As Byte, ByVal sKey As String, ByRef bReturn() As Byte)

Attribute DES_Decode.VB_Description = "解密 sCode:密文16进制串 sKey:密钥文本,前8位有效 bReturn:明文16进制串"

Dim LenTimes As Integer '明文

Dim tempKey() As Byte '存放密钥

Dim BinKey(63) As Byte '64位二进制原始密钥

Dim KeyPC_1(55) As Byte '存放56位密钥

Dim tempCode(7) As Byte '存放8位原始密文

Dim tempReturn(7) As Byte '存放8位明文

Dim BinCode(63) As Byte '存放64位明文

Dim CodeIP(63) As Byte '存放IP置换结果

Dim CodeE(47) As Byte 'E膨胀结果

Dim CodeP(31) As Byte 'P变换结果

Dim RetS(47) As Byte 'S盒运算32位结果

Dim S(7) As Byte 'S盒运算8个结果

Dim CodeS1(5) As Byte: Dim CodeS2(5) As Byte: Dim CodeS3(5) As Byte: Dim CodeS4(5) As Byte

Dim CodeS5(5) As Byte: Dim CodeS6(5) As Byte: Dim CodeS7(5) As Byte: Dim CodeS8(5) As Byte

Dim L0(31) As Byte: Dim R0(31) As Byte

Dim L1(31) As Byte: Dim R1(31) As Byte

Dim L2(31) As Byte: Dim R2(31) As Byte

Dim L3(31) As Byte: Dim R3(31) As Byte

Dim L4(31) As Byte: Dim R4(31) As Byte

Dim L5(31) As Byte: Dim R5(31) As Byte

Dim L6(31) As Byte: Dim R6(31) As Byte

Dim L7(31) As Byte: Dim R7(31) As Byte

Dim L8(31) As Byte: Dim R8(31) As Byte

Dim L9(31) As Byte: Dim R9(31) As Byte

Dim L10(31) As Byte: Dim R10(31) As Byte

Dim L11(31) As Byte: Dim R11(31) As Byte

Dim L12(31) As Byte: Dim R12(31) As Byte

Dim L13(31) As Byte: Dim R13(31) As Byte

Dim L14(31) As Byte: Dim R14(31) As Byte

Dim L15(31) As Byte: Dim R15(31) As Byte

Dim L16(31) As Byte: Dim R16(31) As Byte

Dim C0(27) As Byte: Dim D0(27) As Byte '16个密钥

Dim C1(27) As Byte: Dim D1(27) As Byte

Dim C2(27) As Byte: Dim D2(27) As Byte:

Dim C3(27) As Byte: Dim D3(27) As Byte:

Dim C4(27) As Byte: Dim D4(27) As Byte:

Dim C5(27) As Byte: Dim D5(27) As Byte:

Dim C6(27) As Byte: Dim D6(27) As Byte:

Dim C7(27) As Byte: Dim D7(27) As Byte:

Dim C8(27) As Byte: Dim D8(27) As Byte:

Dim C9(27) As Byte: Dim D9(27) As Byte:

Dim C10(27) As Byte: Dim D10(27) As Byte:

Dim C11(27) As Byte: Dim D11(27) As Byte:

Dim C12(27) As Byte: Dim D12(27) As Byte:

Dim C13(27) As Byte: Dim D13(27) As Byte:

Dim C14(27) As Byte: Dim D14(27) As Byte:

Dim C15(27) As Byte: Dim D15(27) As Byte:

Dim C16(27) As Byte: Dim D16(27) As Byte:

Dim C_D(55) As Byte 'Cn,Dn合并后的存放处

Dim K1(47) As Byte: Dim K2(47) As Byte: Dim K3(47) As Byte: Dim K4(47) As Byte:

Dim K5(47) As Byte: Dim K6(47) As Byte: Dim K7(47) As Byte: Dim K8(47) As Byte:

Dim K9(47) As Byte: Dim K10(47) As Byte: Dim K11(47) As Byte: Dim K12(47) As Byte:

Dim K13(47) As Byte: Dim K14(47) As Byte: Dim K15(47) As Byte: Dim K16(47) As Byte:

Dim i As Integer

Dim j As Integer

'取密钥的前8字节

tempKey = StrConv(sKey, vbFromUnicode)

ReDim Preserve tempKey(7)

For i = 0 To 7

BinKey(i * 8 + 0) = (tempKey(i) And &H80) \ &H80

BinKey(i * 8 + 1) = (tempKey(i) And &H40) \ &H40

BinKey(i * 8 + 2) = (tempKey(i) And &H20) \ &H20

BinKey(i * 8 + 3) = (tempKey(i) And &H10) \ &H10

BinKey(i * 8 + 4) = (tempKey(i) And &H8) \ &H8

BinKey(i * 8 + 5) = (tempKey(i) And &H4) \ &H4

BinKey(i * 8 + 6) = (tempKey(i) And &H2) \ &H2

BinKey(i * 8 + 7) = (tempKey(i) And &H1) \ &H1

'PC_1转换

For i = 0 To 55

KeyPC_1(i) = BinKey(PC_1(i))

'生成C0,D0

For i = 0 To 27

C0(i) = KeyPC_1(i)

D0(i) = KeyPC_1(i + 28)

'***************************************************K1

'生成C1,D1

For i = 0 To 26

C1(i) = C0(i + Lsi(1))

D1(i) = D0(i + Lsi(1))

C1(27) = C0(0)

D1(27) = D0(0)

'组合C1,D1成C_D

For i = 0 To 27

C_D(i) = C1(i)

C_D(i + 28) = D1(i)

'PC_2转换,生成K1

For i = 0 To 47

K1(i) = C_D(PC_2(i))

'***************************************************K2

'生成C2,D2

For i = 0 To 26

C2(i) = C1(i + Lsi(2))

D2(i) = D1(i + Lsi(2))

C2(27) = C1(0)

D2(27) = D1(0)

'组合C2,D2成C_D

For i = 0 To 27

C_D(i) = C2(i)

C_D(i + 28) = D2(i)

'PC_2转换,生成K2

For i = 0 To 47

K2(i) = C_D(PC_2(i))

'***************************************************K3

'生成C3,D3

For i = 0 To 25

C3(i) = C2(i + Lsi(3))

D3(i) = D2(i + Lsi(3))

C3(26) = C2(0)

D3(26) = D2(0)

C3(27) = C2(1)

D3(27) = D2(1)

'组合C3,D3成C_D

For i = 0 To 27

C_D(i) = C3(i)

C_D(i + 28) = D3(i)

'PC_2转换,生成K3

For i = 0 To 47

K3(i) = C_D(PC_2(i))

'***************************************************K4

'生成C4,D4

For i = 0 To 25

C4(i) = C3(i + Lsi(4))

D4(i) = D3(i + Lsi(4))

C4(26) = C3(0)

D4(26) = D3(0)

C4(27) = C3(1)

D4(27) = D3(1)

'组合C4,D4成C_D

For i = 0 To 27

C_D(i) = C4(i)

C_D(i + 28) = D4(i)

'PC_2转换,生成K4

For i = 0 To 47

K4(i) = C_D(PC_2(i))

'***************************************************K5

'生成C5,D5

For i = 0 To 25

C5(i) = C4(i + Lsi(5))

D5(i) = D4(i + Lsi(5))

C5(26) = C4(0)

D5(26) = D4(0)

C5(27) = C4(1)

D5(27) = D4(1)

'组合C5,D5成C_D

For i = 0 To 27

C_D(i) = C5(i)

C_D(i + 28) = D5(i)

'PC_2转换,生成K5

For i = 0 To 47

K5(i) = C_D(PC_2(i))

'***************************************************K6

'生成C6,D6

For i = 0 To 25

C6(i) = C5(i + Lsi(6))

D6(i) = D5(i + Lsi(6))

C6(26) = C5(0)

D6(26) = D5(0)

C6(27) = C5(1)

D6(27) = D5(1)

'组合C6,D6成C_D

For i = 0 To 27

C_D(i) = C6(i)

C_D(i + 28) = D6(i)

'PC_2转换,生成K6

For i = 0 To 47

K6(i) = C_D(PC_2(i))

'***************************************************K7

'生成C7,D7

For i = 0 To 25

C7(i) = C6(i + Lsi(7))

D7(i) = D6(i + Lsi(7))

C7(26) = C6(0)

D7(26) = D6(0)

C7(27) = C6(1)

D7(27) = D6(1)

'组合C7,D7成C_D

For i = 0 To 27

C_D(i) = C7(i)

C_D(i + 28) = D7(i)

'PC_2转换,生成K7

For i = 0 To 47

K7(i) = C_D(PC_2(i))

'***************************************************K8

'生成C8,D8

For i = 0 To 25

C8(i) = C7(i + Lsi(8))

D8(i) = D7(i + Lsi(8))

C8(26) = C7(0)

D8(26) = D7(0)

C8(27) = C7(1)

D8(27) = D7(1)

'组合C8,D8成C_D

For i = 0 To 27

C_D(i) = C8(i)

C_D(i + 28) = D8(i)

'PC_2转换,生成K8

For i = 0 To 47

K8(i) = C_D(PC_2(i))

'***************************************************K9

'生成C9,D9

For i = 0 To 26

C9(i) = C8(i + Lsi(9))

D9(i) = D8(i + Lsi(9))

C9(27) = C8(0)

D9(27) = D8(0)

'组合C9,D9成C_D

For i = 0 To 27

C_D(i) = C9(i)

C_D(i + 28) = D9(i)

'PC_2转换,生成K9

For i = 0 To 47

K9(i) = C_D(PC_2(i))

'***************************************************K10

'生成C10,D10

For i = 0 To 25

C10(i) = C9(i + Lsi(10))

D10(i) = D9(i + Lsi(10))

C10(26) = C9(0)

D10(26) = D9(0)

C10(27) = C9(1)

D10(27) = D9(1)

'组合C10,D10成C_D

For i = 0 To 27

C_D(i) = C10(i)

C_D(i + 28) = D10(i)

'PC_2转换,生成K10

For i = 0 To 47

K10(i) = C_D(PC_2(i))

'***************************************************K11

'生成C11,D11

For i = 0 To 25

C11(i) = C10(i + Lsi(11))

D11(i) = D10(i + Lsi(11))

C11(26) = C10(0)

D11(26) = D10(0)

C11(27) = C10(1)

D11(27) = D10(1)

'组合C11,D11成C_D

For i = 0 To 27

C_D(i) = C11(i)

C_D(i + 28) = D11(i)

'PC_2转换,生成K11

For i = 0 To 47

K11(i) = C_D(PC_2(i))

'***************************************************K12

'生成C12,D12

For i = 0 To 25

C12(i) = C11(i + Lsi(12))

D12(i) = D11(i + Lsi(12))

C12(26) = C11(0)

D12(26) = D11(0)

C12(27) = C11(1)

D12(27) = D11(1)

'组合C12,D12成C_D

For i = 0 To 27

C_D(i) = C12(i)

C_D(i + 28) = D12(i)

'PC_2转换,生成K12

For i = 0 To 47

K12(i) = C_D(PC_2(i))

'***************************************************K13

'生成C13,D13

For i = 0 To 25

C13(i) = C12(i + Lsi(13))

D13(i) = D12(i + Lsi(13))

C13(26) = C12(0)

D13(26) = D12(0)

C13(27) = C12(1)

D13(27) = D12(1)

'组合C13,D13成C_D

For i = 0 To 27

C_D(i) = C13(i)

C_D(i + 28) = D13(i)

'PC_2转换,生成K13

For i = 0 To 47

K13(i) = C_D(PC_2(i))

'***************************************************K14

'生成C14,D14

For i = 0 To 25

C14(i) = C13(i + Lsi(14))

D14(i) = D13(i + Lsi(14))

C14(26) = C13(0)

D14(26) = D13(0)

C14(27) = C13(1)

D14(27) = D13(1)

'组合C14,D14成C_D

For i = 0 To 27

C_D(i) = C14(i)

C_D(i + 28) = D14(i)

'PC_2转换,生成K14

For i = 0 To 47

K14(i) = C_D(PC_2(i))

'***************************************************K15

'生成C15,D15

For i = 0 To 25

C15(i) = C14(i + Lsi(15))

D15(i) = D14(i + Lsi(15))

C15(26) = C14(0)

D15(26) = D14(0)

C15(27) = C14(1)

D15(27) = D14(1)

'组合C15,D15成C_D

For i = 0 To 27

C_D(i) = C15(i)

C_D(i + 28) = D15(i)

'PC_2转换,生成K15

For i = 0 To 47

K15(i) = C_D(PC_2(i))

'***************************************************K16

'生成C16,D16

For i = 0 To 26

C16(i) = C15(i + Lsi(16))

D16(i) = D15(i + Lsi(16))

C16(27) = C15(0)

D16(27) = D15(0)

'组合C16,D16成C_D

For i = 0 To 27

C_D(i) = C16(i)

C_D(i + 28) = D16(i)

'PC_2转换,生成K16

For i = 0 To 47

K16(i) = C_D(PC_2(i))

'**************************************************************************************

'加密过程

'将明文位数扩展为8的倍数

If (UBound(sCode) + 1) Mod 8 > 0 Then ReDim Preserve sCode(((UBound(sCode) + 1) \ 8 + 1) * 8 - 1)

'定义返回密文长度

ReDim bReturn(UBound(sCode))

For j = 0 To UBound(sCode) Step 8

CopyMemory tempCode(0), sCode(j), 8

For i = 0 To 7

BinCode(i * 8 + 0) = (tempCode(i) And &H80) \ &H80

BinCode(i * 8 + 1) = (tempCode(i) And &H40) \ &H40

BinCode(i * 8 + 2) = (tempCode(i) And &H20) \ &H20

BinCode(i * 8 + 3) = (tempCode(i) And &H10) \ &H10

BinCode(i * 8 + 4) = (tempCode(i) And &H8) \ &H8

BinCode(i * 8 + 5) = (tempCode(i) And &H4) \ &H4

BinCode(i * 8 + 6) = (tempCode(i) And &H2) \ &H2

BinCode(i * 8 + 7) = (tempCode(i) And &H1) \ &H1

'IP置换

For i = 0 To 63

CodeIP(i) = BinCode(IP(i))

'分段

For i = 0 To 31

R0(i) = CodeIP(i)

L0(i) = CodeIP(i + 32)

'进行第一次迭代

For i = 0 To 47

CodeE(i) = R0(E(i)) '经过E变换扩充，由32位变为48位

CodeE(i) = CodeE(i) Xor K16(i) '与K16按位作不进位加法运算

'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)

'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

For i = 0 To 31

'P变换

CodeP(i) = RetS(P(i))

'产生L1,R1

R1(i) = L0(i) Xor CodeP(i)

L1(i) = R0(i)

'进行第二次迭代

For i = 0 To 47

CodeE(i) = R1(E(i)) '经过E变换扩充，由32位变为48位

CodeE(i) = CodeE(i) Xor K15(i) '与K15按位作不进位加法运算