On Mon, May 13, 2013, Greg Bryant (grbryant) wrote: > If you encrypt the 32KB block with multiple calls to EVP_CipherUpdate (for > example 4KB at a time), you'll see this effect. Each call to > EVP_CipherUpdate restarts the tweak. I posted a question as whether that's a > bug or a feature a few weeks ago but didn't get any conclusive responses. > AES XTS is the only mode with this issue. Other modes preserve the chaining > across calls to EVP_CipherUpdate. >
That's a feature of how XTS mode is implemented. The normal use for XTS is hard disk encryption in sector size chunks where all the data is available in memory at once. CCM mode doesn't chain either but for different reasons. What you're seeing is that the way the cipher works isn't compatible with the cipher BIO which the enc command uses. We should really disable those modes which don't work properly with enc: that would be GCM, CCM and XTS at present. Steve. -- Dr Stephen N. Henson. OpenSSL project core developer. Commercial tech support now available see: http://www.openssl.org ______________________________________________________________________ OpenSSL Project http://www.openssl.org Development Mailing List [email protected] Automated List Manager [email protected]
