Write an encrypted and decrypted class with ASP

Using ASP to write a simple encryption and decryption class, in this class simple implementation of a cryptographic and decryption. The purpose is to share with you. The cracking of this class is very simple. Just look at my notes and see what's going on. The next time you write a Java encryption and decryption class.

Class Base64class

REM Const

Dim sbase_64_characters Conversion Code

Dim lenstring Calculates the length of a string

Dim icount Counter

Dim returnvalue Return Value

Dim Tempchar Cached Characters

Dim tempstring Cache String

Dim paramstring Parameter String

Dim Temhex Cache Cache Hex

Dim Templow Cache Low

Dim Temphigh Cache High

Dim mod3string

Dim mod4string

Dim tempbinary

Dim Tempbyteone

Dim tempbytetwo

Dim tempbytethree

Dim tempbytefour

Dim Tempsavebitsone

Dim tempsavebitstwo

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Begin Initialization Class

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Private Sub Class_Initialize ()

Sbase_64_characters=abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz09+/endsub

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End Initialization class

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Begin destroying class

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Private Sub Class_Terminate ()

Sbase_64_characters= End Sub

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End Destroy class

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Begin BASE64 encoding an ANSI-encoded string

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Public Function Encode (paramstring)

tempstring=

Returnvalue=

Lenstring=len (paramstring)

If Lenstring<1 Then

Encode=returnvalue

Else

Mod3string=lenstring MoD 3

The number of complements is for easy calculation.

If Mod3string>0 Then

Lenstring=lenstring+3-mod3string

Lenstring=lenstring-3

Begin

For Icount=1 to lenstring step 3

Tempbinary = Mid (paramstring, icount, 3)

Response.Write Tempbinary

Tempbyteone= ASC (Mid (tempbinary, 1, 1)): Tempsavebitsone=tempbyteone and 3

Tempbytetwo = ASC (Mid (Tempbinary, 2, 1)): Tempsavebitstwo=tempbytetwo and 15

Tempchar = ASC (Mid (Tempbinary, 3, 1))

Tempbyteone = Mid (Sbase_64_characters, (Tempbyteone and 252) 4) + 1, 1)

Tempbytetwo = Mid (Sbase_64_characters, (tempbytetwo) Or (Tempsavebitsone *) and &AMP;HFF) + 1, 1)

Tempbytethree = Mid (Sbase_64_characters, (Tempchar) Or (Tempsavebitstwo * 4) and &AMP;HFF) + 1, 1)

Tempbytefour = Mid (Sbase_64_characters, (Tempchar and 63) +1,1)

tempstring = tempbyteone & tempbytetwo &tempByteThree& tempbytefour Returnvalue=returnvalue & Tempstringnext

End

The last few remaining characters to begin processing

If Mod3string>0 Then

Tempbinary = Mid (paramstring, icount, mod3string)

If Mod3string=1 Then

tempstring = tempbinary & Chr ($) & Chr ($) &AMP;CHR (64) complement digits with @ number

else tempstring = tempbinary & Chr ($) &AMP;CHR (64) complement digits with @ number

End If

Returnvalue=returnvalue & TempString

End If

End processing the last remaining few characters

Encode=returnvalue End If End function

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End BASE64 encoding an ANSI-encoded string

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End converts the BASE64 encoded string to an ANSI-encoded string

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Public Function Decode (paramstring)

tempstring=

Returnvalue=

Lenstring=len (paramstring)

If Lenstring<1 Then

Decode=returnvalue

Else

Mod4string=lenstring MoD 4

If mod4string >0 then string length should be a multiple of 4

Decode=returnvalue

Else begin to judge is not the @ number

If Mid (paramstring, lenString-1, 1) = @ Then

mod4string=2

End If

If Mid (paramstring, lenString-2, 1) = @ Then

Mod4string=1

End If

End judgment is not the @ number

If Mod4string>0 Then

Lenstring=lenstring-4

Begin

For Icount=1 to lenstring step 4

tempstring = Mid (paramstring, icount, 4)

Tempbyteone = InStr (Sbase_64_characters, Mid (tempstring, 1, 1))-1

Tempbytetwo = InStr (Sbase_64_characters, Mid (tempstring, 2, 1))-1

Tempbytethree = InStr (Sbase_64_characters, Mid (tempstring, 3,1))-1

Tempbytefour = InStr (Sbase_64_characters, Mid (tempstring, 4, 1))-1

Tempbyteone = Chr ((tempbytetwo) Or (Tempbyteone *4) and &hff) Tempbytetwo = & Chr (((Tempbytethree and 6 0) 4) Or (Tempbytetwo *) and &AMP;HFF)

Tempbytethree = Chr ((Tempbytethree and 3) *) and &AMP;HFF) Or (Tempbytefour and 63))

Tempstring=tempbyteone & Tempbytetwo & Tempbytethree

Returnvalue=returnvalue & TempString

Next

End

Processing the last remaining few characters

If mod4string > 0 Then

Tempstring=center (center (paramstring,4), mod4string)

returnvalue = returnvalue & tempstring

End If

Decode=returnvalue

End If

End If

End Function

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End converts the BASE64 encoded string to an ANSI-encoded string

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Author: CSDN Pxjianke