Thanks for the info Alan. I am going to get a book. What I am referring to, and need a fast implementation of, is this: a.. Find P and Q, two large (e.g., 1024-bit) prime numbers. a.. Choose E such that E is greater than 1, E is less than PQ, and E and (P-1)(Q-1) are relatively prime, which means they have no prime factors in common. E does not have to be prime, but it must be odd. (P-1)(Q-1) can't be prime because it's an even number. a.. Compute D such that (DE - 1) is evenly divisible by (P-1)(Q-1). Mathematicians write this as DE = 1 (mod (P-1)(Q-1)), and they call D the multiplicative inverse of E. This is easy to do -- simply find an integer X which causes D = (X(P-1)(Q-1) + 1)/E to be an integer, then use that value of D. a.. The encryption function is C = (T^E) mod PQ, where C is the ciphertext (a positive integer), T is the plaintext (a positive integer), and ^ indicates exponentiation. The message being encrypted, T, must be less than the modulus, PQ. a.. The decryption function is T = (C^D) mod PQ, where C is the ciphertext (a positive integer), T is the plaintext (a positive integer), and ^ indicates exponentiation. I need a fast implementation of that. ----- Original Message ----- From: "Alan Wolfe" <atrix2@xxxxxxx> To: <gameprogrammer@xxxxxxxxxxxxx> Sent: Tuesday, July 20, 2004 8:32 PM Subject: [gameprogrammer] Re: Fast, easy to use RSA generator > Hey Kevin, > > Seriously, you should get applied cryptography and read it, a really great > book that will teach you alot about cryptography. > > From the author's analasis, he shows that algorithms that rely on wierd > mathematical properties always seem to get cracked or always have a weak > chink in their armor that lets people crack em faster than brute forcing > them. > > The reliable algorithms are all "simple", IE they rely on things like xor, > addition, subtraction and bit rotation, not big complex equations that > mathemeticians like to poke at for fun. > > RSA Data Security, Inc. has made LOTS of encryption algorithms and are > pretty venerable in the encryption world it seems. I'm assuming this is the > company you are talking about when you say RSA but maybe you mean something > else. > > RSA's best publicly known algorithm as of when this book was made (late 90s) > is RC5. > > They actualy have a bounty out to where whoever breaks a message they > encrypted in RC5 will get something like 1 million dollars. > > If youve ever seen those programs that run in the background to analyze SETI > data, they have a similar thing set up for breaking this RC5 message, where > you join a "group" and if your group cracks the message you split the money. > > So far, the prize remains unclaimed (: > > RC5 is not useable w/o a license though, and a very hefty fee. (this is all > to the best of my knowledge of course, this information could be outdated, > or changed by now) > > RC4 however is the next best thing. > > according to the book... > > "RSADSI claims that the algorithm is immune to differential and linear > cryptanalysis, doesnt seem to have any small cycles, and is highly > non-linear. (There are no public cryptanaltic results. RC4 can be in about > 2 & 1700 (256!*256^2) possible states: an enormous number.) .... The > algorithm is simple enough that most programmers can quickly code it from > memory." > > RC4 is public domain. The name is trademarked so if you code it you have > to call it somethign else, but the process itself is no longer protected as > a trade secret so it's all yours to use. > > Best of all, RC4 uses nothing but addition,subtraction and xor so it is > probably genuinely very secure. I found some code on the net, i havent > tested it but it looks good, hope it suits your needs (: > > http://www.cr0.net:8040/code/crypto/rc4/ --------------------- To unsubscribe go to http://gameprogrammer.com/mailinglist.html