Re: [PATCH 2/6] integrity: IMA as an integrity service provider

[Mimi Zohar <zohar@linux.vnet.ibm.com>]

On Fri, 2009-01-30 at 11:07 +1100, James Morris wrote:
> On Thu, 29 Jan 2009, Mimi Zohar wrote:
> 
> > +++ b/security/integrity/ima/Kconfig
> > @@ -0,0 +1,49 @@
> > +# IBM Integrity Measurement Architecture
> > +#
> > +config IMA
> > +	bool "Integrity Measurement Architecture(IMA)"
> > +	depends on ACPI
> > +	select SECURITYFS
> > +	select CRYPTO
> > +	select CRYPTO_HMAC
> > +	select CRYPTO_MD5
> > +	select CRYPTO_SHA1
> > +	select TCG_TPM
> > +	select TCG_TIS
> > +	help
> > +	  The Trusted Computing Group(TCG) runtime Integrity
> > +	  Measurement Architecture(IMA) maintains a list of hash
> > +	  values of executables and other sensitive system files,
> > +	  as they are read or executed. If an attacker manages
> > +	  to change the contents of an important system file
> > +	  being measured, we can tell.
> 
> Out of interest, do you know if the TCG has analyzed their use of SHA-1 
> in light of various attacks on the algorithm over the last few years?
> 
> The IETF has published analysis and recommendations relating to the use of 
> SHA-1 (and other cryptographic hashes) with IP protocols:
> 
> http://www.ietf.org/rfc/rfc4894.txt
> http://www.ietf.org/rfc/rfc4270.txt
> 
> It would be useful to know if similar analysis has been performed for TPM.
> 
> 
> - James

Sorry, the TCG does not have a postion paper on this.  We do not see
the current SHA-1 collision weakness being applicable to how the TPM
is currently being used by IMA.  If, however, it does becomes an issue,
we could replace the SHA-1 template measurement with SHA-256.

Mimi