Convert a VB6 program into Java
Hello everyone,
I have this small VB6 function needed to be converted properly into Java
This is the VB6 function
Public Function Crypt(ByVal Text As String) As String
Dim X As Integer
For X = 1 To Len(Text)
Crypt = Crypt & Chr(Asc(Mid$(Text, Len(Text) - X + 1, 1)) Xor &HA5)
Next X
End Function
It is just a function to invert and encrypt a string. And if you run Crypt(Crypt("10108"), it will give you "10108" back (because of the Xor operator)
My java equivalent is
publicstatic String crypt(String input)
{
int i = 0;
int len = input.length();
int a5 = 0xa5;// variable used in original VB code for encoding
String cryptOutput =new String("");
for (i = 0; i < input.length(); i++)
{
cryptOutput = cryptOutput + ((char)(((byte) input.charAt(len - i - 1)) ^ ((byte)a5)));
}
return cryptOutput;
}
My java function also work in a sense that crypt(crypt("10108") also gives back "10108", but the my crypt("10108") output is different from the VB6 code Crypt("10108"). And it is important for them to be the same... I've been trying without success in finding out why...
Could someone point out to my why there is a difference? Thank you in advance :)
Could someone
[1859 byte] By [
BuggyVBa] at [2007-11-27 6:08:17]
Does this work for you?
public static String crypt(String input)
{
StringBuffer buf = new StringBuffer();
int len = input.length();
int mask = 0xa5; // variable used in original VB code for encoding
for (int i = 0; i < len; i++)
{
buf.append((char) (input.charAt(len - i - 1) ^ mask));
}
return buf.toString();
}
Thanks for the reply quitte. But no, it still the same :(.... crypt("10108") in java returns different result to Crypt("10108") in VB6. Does it work for you?
And I'm having even stranger problem:
Say
Dim text As String
Text = Chr(253) & Chr(253) & Chr(1) & Chr(2) & Chr(Len("10108") / 256) & Chr(Len("10108") Mod 256) & "10108" & Chr(254) & Chr(254)
is different my java equivalent on printed on screen
String msg = new String("");
msg = msg + ((char)253) + ((char)253) + ((char)packetType) + ((char)packetSubType) + ((char)(packet.length() / 256)) + ((char)(packet.length() % 256)) + packet + ((char)254) + ((char)254);
The VB printout only contains 3 characters (even though there is a ...& "10108" & ....
part). Java printout is longer and I can see part of the original message.
I dont know what is going on here... Never that good with bits and bytes :(
> Does it work for you?
Yes, if I got your algorithm right:
public class Xxx {
public static void main(String[] args) {
String org = args[0];
String enc = crypt(org);
print(org);
print(enc);
}
private static void print(String str) {
System.out.println("");
for (int i = 0, len = str.length();i < len;i++) {
System.out.println(((int) str.charAt(i)) + ":" + Integer.toBinaryString(str.charAt(i)));
}
System.out.println("");
}
public static String crypt(String input)
{
StringBuffer buf = new StringBuffer();
int len = input.length();
int mask = 0x00a5;
for (int i = 0; i < len; i++)
{
buf.append((char) (input.charAt(len - i - 1) ^ mask));
}
return buf.toString();
}
}
Test run:
java Xxx hurz
Result:
104:1101000
117:1110101
114:1110010
122:1111010
223:11011111
215:11010111
208:11010000
205:11001101
What's the output of your VB code?
Probably you shouldn't cast to byte, but do this instead:cryptOutput = cryptOutput + (char) (input.charAt(len - i - 1) ^ a5);
This will likely not behave like the original with non-ASCII characters such as € or ?because Chr and Asc use one of the
Windows-character encodings, but the output should still be the same for ASCII characters.
Edit: ugh long lines
