Perfectly clear ! Thanks a lot!
Victor Duchovni wrote: > > On Sun, Dec 21, 2008 at 12:54:44PM -0800, BiGNoRm6969 wrote: > >> >> Using the SHA256 on private key was an idea to easily generate symmetric >> key >> without needs to protect the key itself (generated on the fly from the a >> protected private key for decryption and encryption). >> >> I did not made any decision about my design but I was exploring this >> possibility. All your comments points to the same direction so I will >> explore other alternatives. I am still new in security and I am not sure >> if >> I understand why this way is vulnerable to replay attack. >> >> Does OpenSSL include tools/function to generate symmetric keys ? Other >> suggestions ? > > You are still contemplating designing your own protocol. Purge this idea > from your mind. > > For "store and forward" encrypted messages) use S/MIME or CMS. > > For secure transport use TLS. > > If you want encrypted media, (key stored on storage device, or entered > when needed, protects content of device B) use symmetric crypto with > keys derived from the secret seed (no need for public/private keys, > they add no value) via a secure key derivation function. PBKDF2 from > PKCS#5 version 2.1 is a good choice. In OpenSSL it is called: > > PKCS5_PBKDF2_HMAC_SHA1() > > sadly no documentation is available, so you have to read the source > and/or find examples of its use in existing code. For block devices, > with random I/O there is typically no room for a MAC or IV, so you > use an implicit IV derived from the block number, and accept the > fact that integrity cannot be guaranteed at the block level. Some > "modes" have better error propagation than CBC for this application, > consider one of the newer modes for disk encryption. > > If your problem does not fit any of the above, it would be wise to > describe it. > > -- > Viktor. > ______________________________________________________________________ > OpenSSL Project http://www.openssl.org > User Support Mailing List openssl-users@openssl.org > Automated List Manager majord...@openssl.org > > -- View this message in context: http://www.nabble.com/Question-about-SHA256-on-a-RSA*-key-tp21093222p21129357.html Sent from the OpenSSL - User mailing list archive at Nabble.com. ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager majord...@openssl.org
