CODEWITHSUNDEEP
vb.net
Alfredo Secusana
Alfredo Secusana

Reputation: 5

Code Returns Unicode characters How to Convert to ASCII

Imports Microsoft.VisualBasic

Public Class VigenereCipher

    Public Shared Function Encrypt(ByVal cipherTxt As String, ByVal key As String)
        Dim encryptedText As String = ""
        For i As Integer = 1 To cipherTxt.Length
            Dim temp As Integer = Asc(GetChar(cipherTxt, i)) _
                                  + Asc(GetChar(key, i Mod key.Length + 1))
            encryptedText += Chr(temp)
        Next
        Return encryptedText
    End Function

    Public Shared Function Decrypt(ByVal cipherTxt As String, ByVal key As String)
        Dim decryptedText As String = ""
        For i As Integer = 1 To cipherTxt.Length
            Dim temp As Integer = Asc(GetChar(cipherTxt, i)) _
                                  - Asc(GetChar(key, i Mod key.Length + 1))
            decryptedText += Chr(temp)
        Next
        Return decryptedText
    End Function

End Class

I would want the program to return regular characters because it outputs unicode characters.

Upvotes: 0

Views: 12790

Answers (2)

user3962541
user3962541

Reputation:

The code works fine, since i got the same plain text after decryption : I execute the encryption code with input Encrypt="abcdef" and key=""hxc" it produces the output for temp as follows

when 

i=1  temp= 217 'Ù
i=2  temp= 197 'Å
i=3  temp= 203 'Ë
i=4  temp= 220 'Ò
i=5  temp= 200 'Ò
i=6  temp= 206 'Î

from further checking i got the conclusion that your algorithm will produce a value higher than 150 for most of the inputs. The reference says that, The extended ASCII codes (character code 128-255) There are several different variations of the 8-bit ASCII table. The table below is according to ISO 8859-1, also called ISO Latin-1. Codes 129-159 contain the Microsoft® Windows Latin-1 extended characters.

Comclusion: The problem for producing Unicode characters is that the algorithm you ware choosing will produce a value greater than 127 for temp.

Upvotes: 0

User999999
User999999

Reputation: 2520

Straight from MSDN: You should use the Encoding.Convert Method

Example code (from MSDN):

Public Function UnicodeToAscii( Byval unicodeString as String) As String 


  Dim ascii As Encoding = Encoding.ASCII
  Dim unicode As Encoding = Encoding.Unicode
  ' Convert the string into a byte array. 
  Dim unicodeBytes As Byte() = unicode.GetBytes(unicodeString)

  ' Perform the conversion from one encoding to the other. 
  Dim asciiBytes As Byte() = Encoding.Convert(unicode, ascii, unicodeBytes)

  ' Convert the new byte array into a char array and then into a string. 
  Dim asciiChars(ascii.GetCharCount(asciiBytes, 0, asciiBytes.Length)-1) As Char
  ascii.GetChars(asciiBytes, 0, asciiBytes.Length, asciiChars, 0)
  Dim asciiString As New String(asciiChars)
  Return asciiString
End Function

Upvotes: 3

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