Re: [PHP] Mcrypt: Blowfish or Twofish or no fish? Part 2
On Wed, 22 May 2002, Jimmy Lantz wrote: > Thanx for the suggestions! > Someone mentioned that I could use MD5 and then encrypt the hash, > how would I ever decrypt that? Is'nt MD5 a 1-way thing only? > > Another question? > Should I go for bigger keylength or bigger blocksize or both? What makes > for the best encryption? Does it really make a difference? I'm not exactly crypto-literate, but the idea is to encrypt the thing so that it's not visible by Foo Bar even if he does break into your system. If someone is competent enough to break Mcrypt's 128/256bit cyphers, then it doesn't really matter if you use the "weak" or the "strong" ones. I've used 256bit Rijndael in CBC mode, but I wouldn't feel more/less safe if it was CFB or if it was 3DES. Just my 2c. --thalis > > / Jim > > (and before someone suggest that I read the book Applied cryptography it's > already orderd and on it's way :-) ) -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
RE: [PHP] Mcrypt: Blowfish or Twofish or no fish? Part 2
Jimmy, You could md5 something and send it encrypted and then verify the md5, something similar to sharing keys...md5 is similar to a key...i use it as something similar to kerberos... And yes, MD5 is a one-way hash...which comes in handy... Just remember that bigger is almost always better. I would suggest trying all three (blocksize, keylength, and both) and see which one works best for you. You should see how your system deals with it and then decide...I like to have bigger keylenghts personally... Thanks, Ray Hunter -Original Message- From: Jimmy Lantz [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 22, 2002 12:58 AM To: [EMAIL PROTECTED] Subject: [PHP] Mcrypt: Blowfish or Twofish or no fish? Part 2 Thanx for the suggestions! Someone mentioned that I could use MD5 and then encrypt the hash, how would I ever decrypt that? Is'nt MD5 a 1-way thing only? Another question? Should I go for bigger keylength or bigger blocksize or both? What makes for the best encryption? / Jim (and before someone suggest that I read the book Applied cryptography it's already orderd and on it's way :-) ) -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Mcrypt: Blowfish or Twofish or no fish? Part 2
Yes Jimmy, you are correct. MD5 is a one-way hash. Its used for getting a unique fingerprint of some data (like files / passwords etc) so that it can be compared with another MD5 hash. Thats the point of a hashing algorithm like MD5 and SHA1 - you should never need to decrypt the data. Refer to how Digital signatures and PKI works - they use MD5 hashes. The next question - A bigger keylength means stronger encryption - but it also means more CPU cycles. A bigger blocksize means that bigger chunks of data are encrypted at a time. Its always a balance that needs to be found over here - you cant use a keylength that is 2048 bits - it will give u the strongest encryption, but it will also take a lot of time. Tx, Vinod. On Wed, 22 May 2002 Jimmy Lantz wrote : >Thanx for the suggestions! >Someone mentioned that I could use MD5 and then encrypt the >hash, >how would I ever decrypt that? Is'nt MD5 a 1-way thing only? > >Another question? >Should I go for bigger keylength or bigger blocksize or both? >What makes for the best encryption? > >/ Jim > >(and before someone suggest that I read the book Applied >cryptography it's already orderd and on it's way :-) ) > > >-- PHP General Mailing List (http://www.php.net/) >To unsubscribe, visit: http://www.php.net/unsub.php > _ Click below to visit monsterindia.com and review jobs in India or Abroad http://monsterindia.rediff.com/jobs -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
