Got this from Mordy Ovits <[EMAIL PROTECTED]> Is the following of more than trivial value? It does seem to use L integers... #!/usr/bin/python from sys import*;from string import*;a=argv;[s,p,q]=filter(lambda x:x[:1]!= '-',a);d='-d'in a;e,n=atol(p,16),atol(q,16);l=(len(q)+1)/2;o,inb=l-d,l-1+d while s:s=stdin.read(inb);s and map(stdout.write,map(lambda i,b=pow(reduce( lambda x,y:(x<<8L)+y,map(ord,s)),e,n):chr(b>>8*i&255),range(o-1,-1,-1))) Invoked as: echo 'Top secret message.' | rsa.py 10001 1967cb529 >ciphertext cat ciphertext | rsa.py -d ac363601 1967cb529 * rsa.py (4 lines): Performs RSA public key encryption/decryption. It requires two arguments, and can accept a single option: '-d' for decryption (the default action is encryption). The first argument must be the required exponent, expressed in hexadecimal, and the second is the modulus, also in hex. You still have to choose the correct exponent, whether the '-d' option is present or not; '-d' simply changes the number of bytes read at a single time. As an example: Let us assume the modulus is 6819722537, the encryption exponent is 65537, and the decryption exponent is 2889233921. Then, after converting the numbers to hex, we can encrypt and then decrypt by the following commands: