, Trusted Platform Module
(TPM) is both the name of a published specification
detailing a secure cryptoprocessor
that can store cryptographic keys
that protect information, as well as the general name of implementations of that specification, often called the "TPM chip" or "TPM Security Device" (as designated in certain Dell
BIOS settings). Calling TPM a "chip
" however is a bit of a misnomer since it's a specification for the software written to firmware
on chips as opposed to a physical object on a circuit board. It was dubbed the "Fritz chip" by professor Ross Anderson
, Security Engineering Professor at the University of Cambridge Computer Laboratory
, in reference to the former United States Senator Ernest "Fritz" Hollings
, who according to Anderson "worked tirelessly in Congress to make TC
a mandatory part of all consumer electronics. The TPM specification is the work of the Trusted Computing Group
. The current version of the TPM specification is 1.2 Revision 103, published on July 9 2007
The Trusted Platform Module offers facilities for the secure generation of cryptographic keys
, and limitation of their use, in addition to a hardware
pseudo-random number generator
. It also includes capabilities such as remote attestation
and sealed storage
. "Remote attestation" creates a nearly unforgeable hash key
summary of the hardware and software configuration. The extent of the summary of the software is decided by the program encrypting the data . This allows a third party to verify that the software has not been changed. "Sealing" encrypts data in such a way that it may be decrypted only if the TPM releases the associated decryption key, which it only does for software that can provide the same password that was supplied when software "ownership" of the TPM was initially configured. "Binding" encrypts data using the TPM endorsement key
, a unique RSA
key burned into the chip during its production, or another trusted key descended from it.
A Trusted Platform Module can be used to authenticate hardware devices. Since each TPM chip has a unique and secret RSA key burned in as it is produced, it is capable of performing platform authentication. For example, it can be used to verify that a system seeking access is the expected system.
Generally, pushing the security down to the hardware level in conjunction with software provides more protection than a software-only solution that is more easily compromised by an attacker. However even where a TPM is used, the key is still vulnerable while a software application that has obtained it from the TPM is using it to perform encryption/decryption operations, as has been illustrated in the case of a cold boot attack.
Full disk encryption
applications, such as the BitLocker Drive Encryption
feature of Microsoft
's Windows Vista
and Windows Server 2008 operating systems
, can use this technology to protect the keys used to encrypt the computer's operating system volume
and provide integrity authentication
for a trusted boot pathway (i.e. BIOS
, boot sector
, etc.) A number of third party full disk encryption products also support the TPM chip.
Almost any encryption-enabled application can in theory make use of a TPM, including:
These potential other uses have given rise to privacy concerns. Consequently, to address these concerns, the TPM chip cannot be enabled via software alone - a "physical presence request" operation is required, whereby a human sitting at the computer must acknowledge the request to activate the device via a prompt at BIOS level. Furthermore, each application that uses the TPM must register a unique passphrase when it takes ownership of the TPM in order to prevent other applications from also making unauthorized use of the TPM while it's enabled. Future operating systems are expected to have increased TPM support for additional cryptographic features.
Starting in 2006, many new laptop computers have been sold with a Trusted Platform Module chip built-in. In the future, this concept could be co-located on an existing motherboard
chip in computers, or any other device where a TPM's facilities could be employed, such as a cell phone. Intel
is planning to integrate the TPM capabilities into the southbridge chipset
Trusted Platform Module microcontrollers are currently produced by:
TPM Implementation Brand Names
As a specification that manufacturers follow, (vs a product) manufacturers have their own proprietary implementations that meet the TPM standard.