Hi,
I am attaching the code to encrypt a password & to decrypt the same....
Regards,
aruniima
____________________________________________________________________________
_____________________________________________
import java.util.*;
/*
*The encryption logic is also available in this class(commented) for
*reference and changes.
*/
public class Encryptor
{
private static char inc='0';
private static char dec='1';
public static String decryptPass(String pass) throws
IllegalArgumentException
{
char[] chars = pass.toCharArray();
if((chars.length-1)%2 != 0)
{
throw new
IllegalArgumentException("Incorrect password");
}
char[] result = new char[(chars.length-1)/2];
Character eo = new Character(chars[0]);
if(!Character.isDigit(chars[0]))
{
throw new
IllegalArgumentException("Incorrect password");
}
int evodd = Integer.parseInt(eo.toString());
Character thisChar;
for(int i=1; i<chars.length; i+=2)
{
char incdec = chars[i];
thisChar = new Character(chars[i+1]);
Character comparisonChar = null;
int val=0;
if( incdec!=inc && incdec!=dec )
{
throw new
IllegalArgumentException("Password format incorrect");
}
if(
!Character.isLetterOrDigit(chars[i+1]) )
{
throw new
IllegalArgumentException("The password can only contain letters and digits :
"+pass);
}
if( (i/2)%2 == evodd%2 )
{
if( incdec == inc )
result[(i-1)/2]
= (char)(chars[i+1] - 2);
else
result[(i-1)/2]
= (char)(chars[i+1] + 2);
}
else
{
if( incdec == inc )
result[(i-1)/2]
= (char)(chars[i+1] - 1);
else
result[(i-1)/2]
= (char)(chars[i+1] + 1);
}
}
return new String(result);
}//end of method decryptPass
/*
//Encyption logic:
//1. generate a random number between 0 and 9(inclusive)
//2. Set this to be the first character of the new string
//3. For every input character:
//3.a. Check if it is a digit, uppercase char or lowercase char
//3.b. Assign a comparisonChar based on this check
// '5' for digits
// 'M' for uppercase chars
// 'm' for lowercase chars
//3.c. Compare the input character with the appropriate
comparison char
//3.d. If it is less, set the next char in encrypted string to
'0' else set to '1'.
//3.e. If the index of this char mod 2 equals the random number
mod 2,
// increment the char by two if char added
was '0'.
// decrement the char by two if char added
was '1'.
// else
// increment the char by one if char added
was '0'.
// decrement the char by one if char added
was '1'.
//3.f. Add this modified char to the encrypted string.
*/
public static String encryptPass(String pass) throws
IllegalArgumentException
{
char[] chars = pass.toCharArray();
char[] result = new char[chars.length*2+1];
int evodd = (new Random()).nextInt(10);
result[0] =
Integer.toString(evodd).charAt(0);//(char)evodd;
Character thisChar;
for(int i=0; i<chars.length; i++)
{
thisChar = new Character(chars[i]);
Character comparisonChar = null;
if( Character.isDigit(chars[i]) )
{
comparisonChar = new
Character('5');
}//end of if( thisChar.isDigit() )
else if( Character.isLetter(chars[i]) &&
Character.isUpperCase(chars[i]) )
{
comparisonChar = new
Character('M');
}//end of if( thisChar.isDigit() )
else if( Character.isLetter(chars[i]) &&
Character.isLowerCase(chars[i]) )
{
comparisonChar = new
Character('m');
}//end of if( thisChar.isDigit() )
else
{
throw new
IllegalArgumentException("The password can only contain letters and digits :
"+pass);
}
if( i%2 == evodd%2 )
{
if(
thisChar.compareTo(comparisonChar) < 0 )
{
result[i*2+1] =
inc;
result[i*2+2] =
(char)(chars[i] + 2);
}
else
{
result[i*2+1] =
dec;
result[i*2+2] =
(char)(chars[i] - 2);
}
}
else
{
if(
thisChar.compareTo(comparisonChar) < 0 )
{
result[i*2+1] =
inc;
result[i*2+2] =
(char)(chars[i] + 1);
}
else
{
result[i*2+1] =
dec;
result[i*2+2] =
(char)(chars[i] - 1);
}
}
}
return new String(result);
}
/*
the password received & is checked with the one
stored in the database
The one in the database is encrypted.
Every encryption generates a different key for the
same letter hence
The method receives 2 arguments, one is simple
String from the user &
the other is a encrypted String stored in the
database
The encryption is done when storing the password in
the
database using the method "encryptPass(String)"
*/
public static boolean comparePass(String pswd, String dbpswd)
{
boolean flag = false;
try
{
String enpass = decryptPass(dbpswd);
if(enpass.equals(pswd))
{
flag = true;
}
else
{
flag = false;
}
}
catch(Exception e)
{
System.out.println(e);
}
finally
{
return flag;
}
}
____________________________________________________________________________
_____________________________________________
-----Original Message-----
From: srinivas tadikonda [mailto:[EMAIL PROTECTED]]
Sent: Thursday, July 04, 2002 2:08 PM
To: [EMAIL PROTECTED]
Subject: Password encryption
Hi,
How can I do password encryption and decryption. Please sned code for
encryption and decryption.
Regards
Srinivas
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