User Entered Key

Question

I have used 'DES' to encrypt a file which is viewed through a java program.
If the user wants to read the file they must enter the key to access it it, this all works fine, however I have found that single characters can be changed in the encryption key and it will still be parsed as valid, I believe this is because of Parity bits in the encryption. What is the best way of forcing the user to enter the 'exact' key in order for a successfull match to be made?
Many Thanks,
Craig

Answer 1

The key is generated and the file encrypted using the following keygen, this is then presented to the user which he has to type in when he wants to open the file, is this incorrect?
// Create Key
KeyGenerator keyGen = KeyGenerator.getInstance("DES");
SecretKey key = keyGen.generateKey();
// Prepare Output file
ByteArrayOutputStream tempOut = new ByteArrayOutputStream();
exportXML(tempOut, cookieList);
ByteArrayInputStream tempIn = new ByteArrayInputStream(tempOut.toByteArray());
tempOut.close();
//initialise the cipher
Cipher.getInstance("DES").init(Cipher.ENCRYPT_MODE, key );
// create CipherOutputStream
CipherOutputStream costm = new CipherOutputStream(tempOut, Cipher.getInstance("DES"));
// encrypt data
byte[] b = new byte[8];
int i = istm.read(b);
while (i != -1)
costm.write(b, 0, i);
i = istm.read(b);
costm.close();
// Present key to user
String strRet = "";
if ( key != null )
strRet = toHexString( key.getEncoded() );
System.out.println(strRet);
     * Build a hexadecimal representation of the key
     private static String toHexString( byte[] block )
          StringBuffer buf = new StringBuffer();
          int len = block.length;
for (int i = 0; i < len; i++)
               byte2hex(block, buf);
return buf.toString();
     * Transform a byte into a 2 char hex representation
     private static void byte2hex( byte b, StringBuffer buf )
          char[] hexChars = { '0', '1', '2', '3', '4', '5', '6', '7', '8',
'9', 'A', 'B', 'C', 'D', 'E', 'F' };
int high = ((b & 0xf0) >> 4);
int low = (b & 0x0f);
buf.append(hexChars[high]);
buf.append(hexChars[low]);