First attempt on a for loop

[Remi Lillelien]

Hello all,

I've been working on a paper and pen crypto application.
The time has come for the Keyword cipher, but I feel that my loops here are
clumsy and overly complex.
Can someone give som hints, tips or even solutions to how to optimise these
loops.
I'm still learning so I will work on getting better at choosing good
variable names/descriptors and commenting my code.

Here are the loops in question:

[...]
Function KeywordCipher(ByVal strPlainText As String, ByVal strSecretKey As
String) As String
Dim m As Integer
Dim n As Integer
Dim strCipherChar As Char
Dim p As Integer
Dim K As Integer
Dim C As Integer
Dim i As Integer
Dim j As Integer
Dim counter As Integer = 1
Dim strKeywordChar As Char
Dim strCipherText As String
For i = 1 To strPlainText.Length
strCipherChar = Mid(strPlainText, i, 1)

For n = 0 To chrKeySpace.GetUpperBound(0)
If strCipherChar = chrKeySpace(n) Then
C = CInt(n + 1)
Exit For
End If

Next
For j = counter To strSecretKey.Length
strKeywordChar = Mid(strSecretKey, j, 1)

For m = 0 To chrKeySpace.GetUpperBound(0)
If strKeywordChar = chrKeySpace(m) Then
K = CInt(m + 1)
Exit For
End If

Next

Exit For

Next

p = (C + K) Mod 29
strCipherText = strCipherText + chrKeySpace(CInt((p - 1) Mod29))

If counter < strSecretKey.Length Then
counter += 1
Else
counter = 1
End If
Next

Return (strCipherText)

End Function
[...]

Thank you so much for your time

Nazdarovje,

Remi

[yEaH rIgHt]

A StringBuilder object will speed things way up.

Change this:
Dim strCipherText As String

To this:
Dim strCipherText As New StringBuilder(64)

Hello all,

I've been working on a paper and pen crypto application.
The time has come for the Keyword cipher, but I feel that my loops here are
clumsy and overly complex.
Can someone give som hints, tips or even solutions to how to optimise these
loops.
I'm still learning so I will work on getting better at choosing good
variable names/descriptors and commenting my code.

Here are the loops in question:

[...]
Function KeywordCipher(ByVal strPlainText As String, ByVal strSecretKey As
String) As String
Dim m As Integer
Dim n As Integer
Dim strCipherChar As Char
Dim p As Integer
Dim K As Integer
Dim C As Integer
Dim i As Integer
Dim j As Integer
Dim counter As Integer = 1
Dim strKeywordChar As Char
Dim strCipherText As String
For i = 1 To strPlainText.Length
strCipherChar = Mid(strPlainText, i, 1)

For n = 0 To chrKeySpace.GetUpperBound(0)
If strCipherChar = chrKeySpace(n) Then
C = CInt(n + 1)
Exit For
End If

Next
For j = counter To strSecretKey.Length
strKeywordChar = Mid(strSecretKey, j, 1)

For m = 0 To chrKeySpace.GetUpperBound(0)
If strKeywordChar = chrKeySpace(m) Then
K = CInt(m + 1)
Exit For
End If

Next

Exit For

Next

p = (C + K) Mod 29
strCipherText = strCipherText + chrKeySpace(CInt((p - 1) Mod29))

If counter < strSecretKey.Length Then
counter += 1
Else
counter = 1
End If
Next

Return (strCipherText)

End Function
[...]

Thank you so much for your time

Nazdarovje,

Remi

[yEaH rIgHt]

A StringBuilder object will speed things way up.

Change this:
Dim strCipherText As String

To this:
Dim strCipherText As New StringBuilder(64)

Hello all,

I've been working on a paper and pen crypto application.
The time has come for the Keyword cipher, but I feel that my loops here are
clumsy and overly complex.
Can someone give som hints, tips or even solutions to how to optimise these
loops.
I'm still learning so I will work on getting better at choosing good
variable names/descriptors and commenting my code.

Here are the loops in question:

[...]
Function KeywordCipher(ByVal strPlainText As String, ByVal strSecretKey As
String) As String
Dim m As Integer
Dim n As Integer
Dim strCipherChar As Char
Dim p As Integer
Dim K As Integer
Dim C As Integer
Dim i As Integer
Dim j As Integer
Dim counter As Integer = 1
Dim strKeywordChar As Char
Dim strCipherText As String
For i = 1 To strPlainText.Length
strCipherChar = Mid(strPlainText, i, 1)

For n = 0 To chrKeySpace.GetUpperBound(0)
If strCipherChar = chrKeySpace(n) Then
C = CInt(n + 1)
Exit For
End If

Next
For j = counter To strSecretKey.Length
strKeywordChar = Mid(strSecretKey, j, 1)

For m = 0 To chrKeySpace.GetUpperBound(0)
If strKeywordChar = chrKeySpace(m) Then
K = CInt(m + 1)
Exit For
End If

Next

Exit For

Next

p = (C + K) Mod 29
strCipherText = strCipherText + chrKeySpace(CInt((p - 1) Mod29))

If counter < strSecretKey.Length Then
counter += 1
Else
counter = 1
End If
Next

Return (strCipherText)

End Function
[...]

Thank you so much for your time

Nazdarovje,

Remi

[Cor]

Hi Remi,

Making your own encoding classes is always clumsy and complex.
The biggest deal is that to be able to encode but than to decode.

However there are a lot of encoding classes on msdn.
Have a look for that, and start searching using the keyword "rijndael", that
is one of the classes, but it is a nice startpoint for the search

I hope this helps?

Cor

[Cor]

Hi Remi,

Making your own encoding classes is always clumsy and complex.
The biggest deal is that to be able to encode but than to decode.

However there are a lot of encoding classes on msdn.
Have a look for that, and start searching using the keyword "rijndael", that
is one of the classes, but it is a nice startpoint for the search

I hope this helps?

Cor