Doh.
Thanks
Pete
[email protected] wrote: -----
To: [email protected]
From: "Dr. Stephen Henson"
Sent by: [email protected]
Date: 07/12/2014 10:16PM
Subject: Re: Re : Re: [openssl.org #3442] [patch] AES XTS: supporting custom iv from openssl enc command
From: "Dr. Stephen Henson"
Sent by: [email protected]
Date: 07/12/2014 10:16PM
Subject: Re: Re : Re: [openssl.org #3442] [patch] AES XTS: supporting custom iv from openssl enc command
On Sat, Jul 12, 2014, Peter Waltenberg wrote:
> Or extend EVP_CIPHER_CTX_ctrl() to handle things like changing IV's ? Modes
> like XTS may gain a lot from that, you could use EVP_CIPHER_CTX_copy() to
> avoid repeated key expansion costs, change the IV with EVP_CIPHER_CTX_ctrl()
> and do the next block.
There is already a method to change IVs without expnanding the key again which
should work for XTS (looking at code, not tried it explicitly). You set all
parameters to EVP_EcnryptInit_ex et al to NULL apart from the context and IV.
Subsequenty calls to EVP_EncryptUpdate etc should then use the new IV.
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]
> Or extend EVP_CIPHER_CTX_ctrl() to handle things like changing IV's ? Modes
> like XTS may gain a lot from that, you could use EVP_CIPHER_CTX_copy() to
> avoid repeated key expansion costs, change the IV with EVP_CIPHER_CTX_ctrl()
> and do the next block.
There is already a method to change IVs without expnanding the key again which
should work for XTS (looking at code, not tried it explicitly). You set all
parameters to EVP_EcnryptInit_ex et al to NULL apart from the context and IV.
Subsequenty calls to EVP_EncryptUpdate etc should then use the new IV.
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]
