Dim Key As Long
Packet = txtSend.Text
PacketLength = Len(txtSend.Text)
key = &H82381AC + PacketLength * "17"
For ix = 1 To PacketLength - 1
OneCharacter = Mid$(Packet, ix, 1)
NewCharacter = Asc(OneCharacter) Xor key And &H1F
key = key * "13" Xor &H43B
Next ix
The loop will run about 3 times then overflow. I guess no matter what u do xor will result in Byte,Integer or Long. CDec(Key) will not work I need a way to bypass this so i can Xor large numbers.
You can only XOR integer numbers, not strings. If you want to encrypt a string using XOR, do so by applying XOR character by character to the character codes
Public Function Encrypt(ByVal s As String) As String
Const key As String = "r5^245ADh3%^ywftGY53Gsdr245^Tsfdgw45^fGqw4%6243TefgH563&ot7y"
Dim i As Integer
For i = 1 To Len(s)
Mid(s, i, 1) = Chr(Asc(Mid(s, i, 1)) Xor Asc(Mid(key, i, 1)))
Next i
Return s
End Function
Related
I have a set which has an unknown number of objects. I want to associate a label to each one of these objects. Instead of labeling each object with a number I want to label them with letters.
For example the first object would be labeled A the second B and so on.
When I get to Z, the next object would be labeled AA
AZ? then BA, BB, BC.
ZZ? then AAA, AAB, AAC and so on.
I'm working using Mapbasic (similar to VBA), but I can't seem to wrap my head around a dynamic solution. My solution assumes that there will be a max number of objects that the set may or may not exceed.
label = pos1 & pos2
Once pos2 reaches ASCII "Z" then pos1 will be "A" and pos2 will be "A". However, if there is another object after "ZZ" this will fail.
How do I overcome this static solution?
Basically what I needed was a Base 26 Counter. The function takes a parameter like "A" or "AAA" and determines the next letter in the sequence.
Function IncrementAlpha(ByVal alpha As String) As String
Dim N As Integer
Dim num As Integer
Dim str As String
Do While Len(alpha)
num = num * 26 + (Asc(alpha) - Asc("A") + 1)
alpha = Mid$(alpha, 2,1)
Loop
N = num + 1
Do While N > 0
str = Chr$(Asc("A") + (N - 1) Mod 26) & str
N = (N - 1) \ 26
Loop
IncrementAlpha = str
End Function
If we need to convert numbers to a "letter format" where:
1 = A
26 = Z
27 = AA
702 = ZZ
703 = AAA etc
...and it needs to be in Excel VBA, then we're in luck. Excel's columns are "numbered" the same way!
Function numToLetters(num As Integer) As String
numToLetters = Split(Cells(1, num).Address(, 0), "$")(0)
End Function
Pass this function a number between 1 and 16384 and it will return a string between A and XFD.
Edit:
I guess I misread; you're not using Excel. If you're using VBA you should still be able to do this will the help of an reference to an Excel Object Library.
This should get you going in terms of the logic. Haven't tested it completely, but you should be able to work from here.
Public Function GenerateLabel(ByVal Number As Long) As String
Const TOKENS As String = "ZABCDEFGHIJKLMNOPQRSTUVWXY"
Dim i As Long
Dim j As Long
Dim Prev As String
j = 1
Prev = ""
Do While Number > 0
i = (Number Mod 26) + 1
GenerateLabel = Prev & Mid(TOKENS, i, 1)
Number = Number - 26
If j > 0 Then Prev = Mid(TOKENS, j + 1, 1)
j = j + Abs(Number Mod 26 = 0)
Loop
End Function
I'm am using the code example below to represent an integer as an alphabetic string
Private Function GetExcelColumnName(columnNumber As Integer) As String
Dim dividend As Integer = columnNumber
Dim columnName As String = String.Empty
Dim modulo As Integer
While dividend > 0
modulo = (dividend - 1) Mod 26
columnName = Convert.ToChar(65 + modulo).ToString() & columnName
dividend = CInt((dividend - modulo) / 26)
End While
Return columnName
End Function
I found the above example here:
Converting Numbers to Excel Letter Column vb.net
How do I get the reverse, for example:
123 = DS -- Reverse -- DS = 123
35623789 = BYXUWS -- Reverse -- BYXUWS = 35623789
Is it possible to get the number from the alphabetic string without importing Excel?
I found an answer from another post. This function below will work to get the reverse
Public Function GetCol(c As String) As Long
Dim i As Long, t As Long
c = UCase(c)
For i = Len(c) To 1 Step -1
t = t + ((Asc(Mid(c, i, 1)) - 64) * (26 ^ (Len(c) - i)))
Next i
GetCol = t
End Function
For a project I am developing I need to use some kind of encryption algorithm to encrypt some sensitive data, where each user has a unique hex key.
Basically I have to encrypt a string and write it to a file to import to a Access database (we are not authorised to use other RDBMS as the company policies don't allow it).
So while researching what algorithms to use, I've came across this awesome sample of an XOR algorithm from VBA Express, but there are some limitations with this particular algorithm (please correct me if I'm wrong) :
For certain combinations of string vs key, a overflow happens;
Excel uses a "different" ASCII code table which causes some entropy as well (can't use the first 32 codes because they refer to special characters);
I want to avoid special characters (line feeds, carriage returns) because I want to write to a file and if they exist I can't read the file as the splits will go bad.
With this being said, I can't maintain a 1 to 1 relationship of encoding and decoding.
So should I use another encryption system or are there changes should I do to fix this bad encryption?
Should I use another reading/writing file system other than line by line?
The code to generate the keys to test
Private Sub getDictionaryValues()
Dim atc As String
Dim wsheet As Worksheet
Dim wstmp As Worksheet
Dim rng As Range
Dim k As Long, j As Long
Dim arrrr(1 To 223) As String
Dim arc()
On Error Resume Next
j = 2
Set wsheet = ThisWorkbook.Worksheets("Sheet4")
arc = Array("0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F")
For i = 33 To 255
arrrr(i - 32) = Chr(i)
Next i
For k = LBound(arc) To UBound(arc)
For i = LBound(arrrr) To UBound(arrrr)
atc = XorC(arrrr(i), arc(k))
wsheet.Range(Cells(j, 1), Cells(j, 1)) = arc(k)
wsheet.Range(Cells(j, 2), Cells(j, 2)) = i + 32
wsheet.Range(Cells(j, 3), Cells(j, 3)) = arrrr(i)
wsheet.Range(Cells(j, 4), Cells(j, 4)) = Right(atc, Len(atc) - 3)
wsheet.Cells(j, 5) = XorC(atc, arc(k))
'wsheet.Cells(j, 6) = getUnicode(arrrr(i), arc(k))
j = j + 1
Next i
atc = vbNullString
Next k
End Sub
My version of the Xor algorithm
Function XorC(ByVal sData As String, ByVal sKey As String) As String
Dim l As Long, i As Long, byIn() As Byte, byOut() As Byte, byKey() As Byte
Dim bEncOrDec As Boolean
Dim addVal
If Len(sData) = 0 Or Len(sKey) = 0 Then XorC = "Invalid argument(s) used": Exit Function
If Left$(sData, 3) = "xxx" Then
bEncOrDec = False 'decryption
sData = Mid$(sData, 4)
Else
bEncOrDec = True 'encryption
End If
byIn = sData
byOut = sData
byKey = sKey
If bEncOrDec = True Then
addVal = 32
Else
addVal = 1 * -32
End If
l = LBound(byKey)
For i = LBound(byIn) To UBound(byIn) - 1 Step 2
If (((byIn(i) + Not bEncOrDec) Xor byKey(l)) + addVal) > 255 Then
byOut(i) = (((byIn(i) + Not bEncOrDec) Xor byKey(l)) + addVal) Mod 255 + addVal
Else
'If bEncOrDec Then
If ((byIn(i) + Not bEncOrDec) Xor byKey(l)) - addVal < 32 Then byOut(i) = ((byIn(i) + Not bEncOrDec) Xor byKey(l)) + addVal
If ((byIn(i) + Not bEncOrDec) Xor byKey(l)) - addVal > 255 Then byOut(i) = ((byIn(i) + Not bEncOrDec) Xor byKey(l)) - addVal
If ((byIn(i) + Not bEncOrDec) Xor byKey(l)) > 32 And (byIn(i) + Not bEncOrDec) Xor byKey(l) < 256 Then byOut(i) = ((byIn(i) + Not bEncOrDec) Xor byKey(l))
End If
l = l + 2
If l > UBound(byKey) Then l = LBound(byKey)
Next i
XorC = byOut
If bEncOrDec Then XorC = "xxx" & XorC 'add "xxx" onto encrypted text
End Function
I have read through the answers here https://stackoverflow.com/a/14332574/44080
I've also tried to produce equivalent VB.net code:
Option Strict ON
Public Function ParseHex(hexString As String) As Byte()
If (hexString.Length And 1) <> 0 Then
Throw New ArgumentException("Input must have even number of characters")
End If
Dim length As Integer = hexString.Length \ 2
Dim ret(length - 1) As Byte
Dim i As Integer = 0
Dim j As Integer = 0
Do While i < length
Dim high As Integer = ParseNybble(hexString.Chars(j))
j += 1
Dim low As Integer = ParseNybble(hexString.Chars(j))
j += 1
ret(i) = CByte((high << 4) Or low)
i += 1
Loop
Return ret
End Function
Private Function ParseNybble(c As Char) As Integer
If c >= "0"C AndAlso c <= "9"C Then
Return c - "0"C
End If
c = ChrW(c And Not &H20)
If c >= "A"C AndAlso c <= "F"C Then
Return c - ("A"C - 10)
End If
Throw New ArgumentException("Invalid nybble: " & c)
End Function
Can we remove the compile errors in ParseNybble without introducing data conversions?
Return c - "0"c Operator '-' is not defined for types 'Char' and 'Char'
c = ChrW(c And Not &H20) Operator 'And' is not defined for types 'Char' and 'Integer'
As it stands, no.
However, you could change ParseNybble to take an integer and pass AscW(hexString.Chars(j)) to it, so that the data conversion takes place outside of ParseNybble.
This solution is much much faster than all the alternative i have tried. And it avoids any ParseNybble lookup.
Function hex2byte(s As String) As Byte()
Dim l = s.Length \ 2
Dim hi, lo As Integer
Dim b(l - 1) As Byte
For i = 0 To l - 1
hi = AscW(s(i + i))
lo = AscW(s(i + i + 1))
hi = (hi And 15) + ((hi And 64) >> 6) * 9
lo = (lo And 15) + ((lo And 64) >> 6) * 9
b(i) = CByte((hi << 4) Or lo)
Next
Return b
End Function
I am banging my head against the wall for a while now trying different techniques.
None of them are working well.
I have two strings.
I need to compare them and get an exact percentage of match,
ie. "four score and seven years ago" TO "for scor and sevn yeres ago"
Well, I first started by comparing every word to every word, tracking every hit, and percentage = count \ numOfWords. Nope, didn't take into account misspelled words.
("four" <> "for" even though it is close)
Then I started by trying to compare every char in each char, incrementing the string char if not a match (to count for misspellings). But, I would get false hits because the first string could have every char in the second but not in the exact order of the second. ("stuff avail" <> "stu vail" (but it would come back as such, low percentage, but a hit. 9 \ 11 = 81%))
SO, I then tried comparing PAIRS of chars in each string. If string1[i] = string2[k] AND string1[i+1] = string2[k+1], increment the count, and increment the "k" when it doesn't match (to track mispellings. "for" and "four" should come back with a 75% hit.) That doesn't seem to work either. It is getting closer, but even with an exact match it is only returns 94%. And then it really gets screwed up when something is really misspelled. (Code at the bottom)
Any ideas or directions to go?
Code
count = 0
j = 0
k = 0
While j < strTempName.Length - 2 And k < strTempFile.Length - 2
' To ignore non letters or digits '
If Not strTempName(j).IsLetter(strTempName(j)) Then
j += 1
End If
' To ignore non letters or digits '
If Not strTempFile(k).IsLetter(strTempFile(k)) Then
k += 1
End If
' compare pair of chars '
While (strTempName(j) <> strTempFile(k) And _
strTempName(j + 1) <> strTempFile(k + 1) And _
k < strTempFile.Length - 2)
k += 1
End While
count += 1
j += 1
k += 1
End While
perc = count / (strTempName.Length - 1)
Edit: I have been doing some research and I think I initially found the code from here and translated it to vbnet years ago. It uses the Levenshtein string matching algorithm.
Here is the code I use for that, hope it helps:
Sub Main()
Dim string1 As String = "four score and seven years ago"
Dim string2 As String = "for scor and sevn yeres ago"
Dim similarity As Single =
GetSimilarity(string1, string2)
' RESULT : 0.8
End Sub
Public Function GetSimilarity(string1 As String, string2 As String) As Single
Dim dis As Single = ComputeDistance(string1, string2)
Dim maxLen As Single = string1.Length
If maxLen < string2.Length Then
maxLen = string2.Length
End If
If maxLen = 0.0F Then
Return 1.0F
Else
Return 1.0F - dis / maxLen
End If
End Function
Private Function ComputeDistance(s As String, t As String) As Integer
Dim n As Integer = s.Length
Dim m As Integer = t.Length
Dim distance As Integer(,) = New Integer(n, m) {}
' matrix
Dim cost As Integer = 0
If n = 0 Then
Return m
End If
If m = 0 Then
Return n
End If
'init1
Dim i As Integer = 0
While i <= n
distance(i, 0) = System.Math.Max(System.Threading.Interlocked.Increment(i), i - 1)
End While
Dim j As Integer = 0
While j <= m
distance(0, j) = System.Math.Max(System.Threading.Interlocked.Increment(j), j - 1)
End While
'find min distance
For i = 1 To n
For j = 1 To m
cost = (If(t.Substring(j - 1, 1) = s.Substring(i - 1, 1), 0, 1))
distance(i, j) = Math.Min(distance(i - 1, j) + 1, Math.Min(distance(i, j - 1) + 1, distance(i - 1, j - 1) + cost))
Next
Next
Return distance(n, m)
End Function
Did not work for me unless one (or both) of following are done:
1) use option compare statement "Option Compare Text" before any Import declarations and before Class definition (i.e. the very, very first line)
2) convert both strings to lowercase using .tolower
Xavier's code must be correct to:
While i <= n
distance(i, 0) = System.Math.Min(System.Threading.Interlocked.Increment(i), i - 1)
End While
Dim j As Integer = 0
While j <= m
distance(0, j) = System.Math.Min(System.Threading.Interlocked.Increment(j), j - 1)
End While