Now maybe I have this all wrong, but it is my understanding that a known plaintext attack is when the cracker knows part of the plaintext of an encrypted file. Then he/she uses that and runs the inverse of the algorithm to calculate the key. Whether or not I am right about what known plaintext means, isn't the entirely possible on all of the symmetric algorithms out there? If I grab a file that I know is, say, a standard credit card transaction form, and I know what the first 256 bytes are because they are always the same, shouldn I always be able to find the entire key that corresponds with those 256 bytes? (assuming the key is 2048 bits or less) And then with that key decrypt the whole file? Maybe I am missing something but it seems that all the symmetric algorithms are vulnerable to this, and I thought of a fix, but it involves having two keys (or one thats twice as big) -- thecrow@iconn.net "It can't rain all the time" RSA ENCRYPTION IN 3 LINES OF PERL --------------------------------------------------------- #!/bin/perl -sp0777i<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<j]dsj $/=unpack('H*',$_);$_=`echo 16dio\U$k"SK$/SM$n\EsN0p[lN*1 lK[d2%Sa2/d0$^Ixp"|dc`;s/\W//g;$_=pack('H*',/((..)*)$/)