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17

Generally one has to know what TPMs and TXT and all these technologies are aimed to protect from, because there are misunderstandings. TPMs, generally, enable 5 distinct processes, and only those: Integrity measurement – computation of a cryptographic hash of a platform component Authenticated boot – a process by which a platform's state (the sum of its ...


13

You don't. Some vendors do indeed ship backdoors with their products, and many computers come with "crapware" pre-installed as a source of revenue for the manufacturers. Even apps that don't contain a backdoor can cause other damage (e.g. Browser toolbars that track browsing). Same concerns apply with hardware, especially in networking equipment. What you ...


10

HTTPS (i.e. SSL/TLS) encrypts all HTTP communication including the entire URL. HTTPS does not protect the domain name as this is sent to the DNS in the clear, but it does protect the rest of the URL. Other apps don't have access to your app's SSL/TLS encrypted traffic including URLs. So as long as the SSL/TLS connection is setup securely an attacker won't be ...


7

The Storage Root Key (SRK) is used to wrap TPM protected keys which can be stored outside the TPM. That data stored outside the TPM can be decrypted by passing it back through the TPM again for a decryption operation. Keys wrapped by the SRK can themselves be used to wrap other keys, too. This method of wrapping can be used to create a key hierarchy of ...


7

Theoretically, to ascertain what a chip does, you break it apart and reverse-engineer it. In practice, this will be nigh impossible to do. Actually, even for software, for which you have the actual source code, you cannot guarantee that the code really always does what you believe it does (otherwise we would be able to produce bug-free code). This is not a ...


6

All the relevant tools are available for Linux, likely even more than elsewhere. Much the open source spirit, you have to build everything yourself. A free version of MS Bitlocker is suggested if you google "IBM blueprint eCryptFS TPM". Trousers also supports a PKCS#11 interface that allows integration with, e.g., Firefox. With Linux IMA, you get a nice ...


6

Matthew Garrett has some nice blog posts on UEFI Secure Boot. Concerning your question he writes: Anyone can pay $99 and get their binaries signed. So why won't malware authors just do that? For starters, you'll need to provide some form of plausible ID for Verisign to authenticate you and hand over access. So, sure, you provide some sort of fake ID. ...


6

You don't. Most of the alleged backdoors have been software problems (Google for _NSAKEY, or Digital Encryption Standard and NSA interference, or Huawei and back doors), but a hardware backdoor isn't out of the question. The issue of concealing "intellectual property" or other concerns in proprietary software or hardware make this problem worse. If all ...


6

Try tpm-luks [1], which is a script that will assist in storing a new secret both in the TPM's NVRAM and a LUKS key slot. This should do the trick: $ tpm-luks -c -d <device> You can find your LUKS device with: # blkid -t TYPE=crypto_LUKS I released tpm-luks very recently, so its only available in git ATM. [1] ...


6

When a TPM provides a remote attestation, several components are involved: the TPM as a tamper-resistant device containing a root of trust; the TPM as a device to measure the software running on the main processor and produce an attestation; software to connect to the TPM and retrieve the attestation and transmit it (this software is merely relaying a ...


6

Trusted Execution Technology is coupled with a collection of security features available on the modern Intel chipset. The Trusted Platform Module (TPM) and other DRM like features are also in this bundle. The reasoning behind this is because of abstraction, which is more commonly attributed to a software architecture. The commonality behind all of these ...


6

There's basically two way of doing this; SRTM (Static Root of Trust for Measurements) and DRTM (Dynamic Root of Trust for Measurements). SRTM takes place at system boot. The first thing booting up - normally the BIOS boot block - which is the Core Root of Trust for Measurements (CRTM) - will measure the BIOS and send the value (hash) to the TPM (within ...


5

The TPM doesn't stop the boot. The boot will still continue, but the PCRs will have a different value in them than they used to (since now the BIOS is different than it was before). As a result, the system will be unable to unseal the sealed data. Of course, if the bootloader or kernel is unable to unseal the sealed partition, depending on how it is ...


5

From Joanna Rutkowska's blog: (and I admit I'm skating at the edge of my understanding here...) When you load a hypervisor using TXT, the SENTER instruction would first apply the VT-d protections around the hypervsior image, then do the measurements, and only then load it, with VT-d protections still in-place. And her more complete explanation: ...


5

A well designed TPM should be pretty resilient to tampering, but a truly determined attacker could try doing something like dissolving the casing and reading information directly off the chip. It's a pain staking and highly technical process, so probably isn't a likely case in most situations, but if the value of the material is known to be high enough, it ...


5

Disclaimer: I'm not a TPM expert - most of this has come from a half hour's worth of research. I've managed to cobble together a reasonable understanding of the process and details from the TCG TPM spec, the TPM API documentation on MSDN, and various papers on the subject. The SRK is an RSA key pair (of at least 2048-bit size) that is used as the root for ...


5

The TCG Trusted Computing concept devices the BIOS into two parts. The initial BIOS is assumed to be secure and will initialize the TPM. This so-called CRTM will then measure the remaining BIOS components and log their values in the TPM. From the spec it appears that CMOS data is part of that measurement and is stored to PCR1. But since a changed BIOS ...


5

The TPM main specification is meant to be platform-independent. That is why no details about what is actually measured during startup are contained, because obviously the components differ from platform to platform. If you are interested in what is measured during the boot of a PC, you should take a look at section 1.3 (Overview of Measurement Process) of ...


4

Real security enhancements are created if you are buying for a commercial or governmental enterprise but at a cost related to supportability. For the majority of home users who want nothing more than a Microsoft desktop and never modify their purchased system it will also provided added security. For the home user that wants to dual boot (a very small ...


4

From what I know, nothing prevent this in practice, but the code was not written yet. You can take a look however on http://publib.boulder.ibm.com/infocenter/lnxinfo/v3r0m0/index.jsp?topic=%2Fliaai%2Fecrypts%2Fliaaiecryptfs.htm The idea is use tpm_sealdata to encrypt a file, and then this can be unlocked only if the boot was not fiddled with. You may ...


4

Yes. You can see both functions as being really two separate things, i.e., DRTM (Dynamic Root of Trust for Measurement) is just another way to extend PCR values (17-22) (like SRTM) while Remote Attestation will take whatever PCR you which to use (much like the SEAL operation). There’s no dependency or real link between those functionalities. If you want ...


4

Many TPMs will allow a backup to be stored of the key either prior to loading it on to the TPM or via some kind of export. As long as you have the key, you can reload it on a new TPM if the TPM fries. I actually had this exact thing happen with an IBM ThinkPad with an early TPM where the TPM circuit fried and I had to replace the system board. I was ...


4

I did a talk at Blackhat a few years ago (actually 10 now) that revisited Trusting Trust: http://www.blackhat.com/presentations/bh-usa-04/bh-us-04-maynor.pdf I followed up with an article written for Linux Journal in 2005: http://www.linuxjournal.com/article/7839 I've been researching this topic for almost 15 years now and I can tell you the takeaway from ...


4

With version 1.2, that would be the concept of Locality which is implemented in hardware. In reality, the communication is not authenticated and 1.2 is -theoretically- still vulnerable to version 1.1 reset attack but it as never been proven (the window of attack is way much smaller). One important thing to consider: not all TPMs are made equal and you get ...


4

It's complicated. Both are Root of Trust for Measurements meaning they can be used to measure the running environment. The main problem with SRTM is that you need to keep measurements of the entire platform boot sequence (BIOS config, 3rd party boot rom (e.g. network cards), etc) and this includes a LOT of code. Any change to any of this requires new ...


3

Does "dynamic chain of trust" support remote attestation? When a dynamic launch is used on an area of memory, specific PCR indexes in the TPM are used to used to record the state of that software. If these PCR indexes are included in the attestation request by the challenger, then that software would be attested to in the response. These PCR indexes are ...


3

Because it needs isolation to make sure the measurements cannot be manipulated (TOCTOU style of attacks) by anything (e.g. DMA-enabled device). If you like, you can see this as a firewall for I/O and interrupt - obviously, it's not but you get the picture. VT-d is simply Intel’s term to describe their IOMMU. AMD call it AMD-Vi. The role of this unit is to ...


3

--- this is comment, not an answer --- http://www.intel.com/design/mobile/platform/downloads/Trusted_Platform_Module_White_Paper.pdf BIOS Code The TCPA specifies the measurement of integrity of BIOS code at system startup. In order to accomplish such integrity measurement and reporting, the system BIOS has to be enhanced with integrity measurement ...


3

You are mixing up two technologies here it seems. First, there is UEFI and its Secure Boot feature. Secure Boot can be used to assure that your boot loader and your OS kernel are not tampered with. In order to do so, your boot loader and kernel need to be signed digitally and your UEFI configuration must contain the certificates/signatures needed to verify ...



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