Announcement - rsyncrypto 0.02 released

Shachar Shemesh rsync at
Sun Feb 6 11:32:47 GMT 2005

Hi all,

I'm sorry if this is off topic here. I'll send this one anyways, but do 
let me know if you are interested in related project's release 
announcements so that I don't spam this list unnecessarily in the future.

rsyncrypto is a utility that encrypts file in a rsync friendly way. 
Small changes to the plain text file will result in small changes to the 
cypher text file. The encryption takes place as a preprocessing step to 
rsyncing the content, and is performed entirely on one side of the 
connection. The other side need not have any method to decrypt the files 
at all.

The encryption used is AES with any block size (256 bits by default), 
and the file key is encrypted using RSA. The encrypting machine need not 
have the RSA private key in order to prepare the files for rsyncing 
(encryption). It can also perform decryption without the private key, 
assuming meta-information (stored in a different file) is not lost. If 
this meta-information file is lost, it can be recovered with the use of 
the RSA private key.

rsyncrypto uses the same basic method used in gzip's "rsyncable" patch 
to restart blocks from the original IV, thus localizing plain text 
changes in the cypher text.

Version 0.02 is still marked "alpha", though it has passed regression 
tests, and is fairly reliable in decrypting and encrypting the files.

rsyncrypto is written in C++, and is available under the GPL. Please 
feel free to visit the project's summary page at

Thanks, and sorry about the noise,


Shachar Shemesh
Lingnu Open Source Consulting ltd.

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