From: Julian <julian.paceross@gm...>  20080625 07:38:46

Thanks Shachar. 2008/6/24 Shachar Shemesh <shachar@...>: > Hi all, > > Version 1.11 of your favorite rsync friendly encryption program (it is, > isn't it?) has just been released. Many many many new stuff, addressing > almost all of the open issues recently raised. > > Compilation should now just work for cygwin, and as far as I can tell, > for Mac OS X (not sure about that, though). I can't tell if the run time > problem has been resolved or not, as it does not happen on my systems. > > Error messages have been greatly improved. If a file cannot be opened, > rsyncrypto will report which file that was. Also, in case of an error, > only the errored file will be aborted, and rsyncrypto will continue its > operation. It will print an additional error report at the end of the > entire encryption process. > > Also, I have finally fixed the oldest bug of them all. The one that > tripped Frederico. If an attempt is made to decrypt a file with no valid > symmetric key, it will be reported as an error and processing will > continue, rather than issue a segmentation fault. > > Please bear in mind that I am not 100% sure that my code for detecting > whether the private key is available is correct. Technical details > further on, but in for those not interested in the details, please check > this with your system, and make sure cold decryption works for you. > > As usual, share and enjoy. > Shachar > > Technical stuff: > RSA works by taking a modulo based power. So if the message is "m", the > encrypted message C will be M^e mod n. e is a fairly standard number > (typically, either 3 or 2^16+1 = 65537). "n" is the "public key", and is > devised by generating two prime numbers, called "p" and "q", where > n=p*q. "p" and "q" are the private key. > > What some people do not know is that you don't actually need p and q in > order to perform a decryption. p and q are not, theoretically, used > directly. Instead, a number, d, is derived from p and q. The decryption > process can be described as M = C^d mod n. This means you need d and n > in order to decrypt, but you don't need p and q. > > Typically, p and q are being stored, for no other reason than to save on > processing. In practice, openssl will typically calculate M1 = C^d mod p > and M2 = C^D mod q, and then combine M1 and M2 into M using the Chinese > remainder theorem. For that reason, an OpenSSL private key will, > typically, have p and q, and these are the numbers that I check exist or > not to find out whether I have the private key. > > Like I said before, the private key can be used even without p and q. If > that is the case, rsyncrypto may incorrectly deduce that the private key > is not present, and fail the decryption despite all data being > available. This is what I want you all to test for me  that you can > perform cold (i.e.  without the symmetric keys) decryption with your > private key. > > Thanks > > >  > Check out the new SourceForge.net Marketplace. > It's the best place to buy or sell services for > just about anything Open Source. > http://sourceforge.net/services/buy/index.php > _______________________________________________ > Rsyncryptodevel mailing list > Rsyncryptodevel@... > https://lists.sourceforge.net/lists/listinfo/rsyncryptodevel > 