ISO/IEC 11889-1:2009
(Main)Information technology — Trusted Platform Module — Part 1: Overview
Information technology — Trusted Platform Module — Part 1: Overview
ISO/IEC 11889 defines the Trusted Platform Module (TPM), a device that enables trust in computing platforms in general. ISO/IEC 11889-1:2009 is an overview of the TPM. It describes the TPM and how it fits into the trusted platform. ISO/IEC 11889-1:2009 describes trusted platform concepts such as the trust boundary, transitive trust, integrity measurement, and integrity reporting.
Technologies de l'information — Module de plate-forme de confiance — Partie 1: Aperçu général
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INTERNATIONAL ISO/IEC
STANDARD 11889-1
First edition
2009-05-15
Information technology — Trusted
Platform Module —
Part 1:
Overview
Technologies de l'information — Module de plate-forme de confiance —
Partie 1: Aperçu général
Reference number
ISO/IEC 11889-1:2009(E)
©
ISO/IEC 2009
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ISO/IEC 11889-1:2009(E)
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ISO/IEC 11889-1:2009(E)
Table of Contents
1. Scope 1
2. Abbreviated Terms 1
3. The Trusted Platform 4
3.1 Trusted Platform Building Block 4
3.2 The Trust Boundary 4
3.3 Transitive Trust 4
3.3.1 Basic Trusted Platform features 5
3.4 Integrity Measurement 6
3.5 Integrity Reporting 7
4. The TPM 7
4.1 Cryptographic Algorithms Required with TPM 7
4.1.1 Algorithm Assumptions 8
4.2 Operating Systems Supported by TPM 8
4.3 Protected Capabilities 8
4.4 Trusted Platform Module components 8
4.5 Naming Conventions 10
4.6 Privacy Considerations 11
4.7 TPM Operational States 12
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ISO/IEC 11889-1:2009(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with ISO and IEC, also
take part in the work. In the field of information technology, ISO and IEC have established a joint
technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives,
Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft
International Standards adopted by the joint technical committee are circulated to national bodies for
voting. Publication as an International Standard requires approval by at least 75 % of the national
bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights.
ISO/IEC 11889-1 was prepared by the Trusted Computing Group (TCG) and was adopted, under
the PAS procedure, by Joint Technical Committee ISO/IEC JTC 1, Information technology, in
parallel with its approval by national bodies of ISO and IEC.
ISO/IEC 11889 consists of the following parts, under the general title Information technology —
Trusted Platform Module:
⎯ Part 1: Overview
⎯ Part 2: Design principles
⎯ Part 3: Structures
⎯ Part 4: Commands
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ISO/IEC 11889-1:2009(E)
Introduction
Designers of secure distributed systems, when considering the exchange of information between
systems, must identify the endpoints of communication. The composition and makeup of the
endpoint is as important to the overall ability of the system to serve as an authentication and
attestation device of the system as is the communications protocol.
Endpoints are minimally comprised of asymmetric keys, key storage and processing that protects
protocol data items. Classic message exchange based on asymmetric cryptography suggests that
messages intended for one and only one individual can be encrypted using a public key.
Furthermore, the message can be protected from tampering by signing with the private key.
Keys are communication endpoints and improperly managed keys can result in loss of attestation
and authentication. Additionally, improperly configured endpoints may also result in loss of
attestation and authentication ability.
This is an informative background document and contains no specifications or normative
information. To find normative information and specifications about the TPM, refer to
ISO/IEC 11889-2 to ISO/IEC 11889-4.
A Trusted Platform Module (TPM) is an implementation of a defined set of capabilities that is
intended to provide authentication and attestation functionality for a computing device, and protect
information by controlling access to plain-text data.
A TPM is self-sufficient as a source of authentication and as a means of enhancing the protection of
information from certain physical attacks. A TPM requires the cooperation of a TCG “Trusted
Building Block” (outside the TPM, that is also part of the computing device) in order to provide
attestation and protect information from software attacks on the computing device.
Typical TPM implementations are affixed to the motherboard of a computing device.
A computing device that contains both a TPM and a Trusted Building Block is called a Trusted
Platform. Trusted Platforms offer improved, hardware-based security in numerous applications,
such as file and folder encryption, local password management, S-MIME e-mail, VPN and PKI
authentication and wireless authentication for 802.1x and LEAP.
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ISO/IEC 11889-1:2009(E)
Figure 1. TPM Documentation Roadmap
Start of informative comment
ISO/IEC 11889 is from the Trusted Computing Group (TCG) Trusted Platform Module (TPM)
specification 1.2 version 103. The part numbers for ISO/IEC 11889 and the TCG specification do
not match. The reason is the inclusion of the Overview document that is not a member of the TCG
part numbering. The mapping between the two is as follows:
ISO Reference TCG Reference
Part 1 Overview Not published
Part 2 Design Principles Part 1 Design Principles
Part 3 Structures Part 2 Structures
Part 4 Commands Part 3 Commands
End of informative comment
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INTERNATIONAL STANDARD ISO/IEC 11889-1:2009(E)
Information technology — Trusted Platform Module —
Part 1:
Overview
1. Scope
ISO/IEC 11889 defines the Trusted Platform Module (TPM), a device that enables trust in
computing platforms in general. ISO/IEC 11889 is broken into parts to make the role of each
document clear. Any version of the standard requires all parts to be a complete standard.
A TPM designer MUST be aware that for a complete definition of all requirements necessary to
build a TPM, the designer MUST use the appropriate platform specific specification for all TPM
requirements.
Part 1 provides an overview of the concepts behind the TPM and trusted platforms.
2. Abbreviated Terms
Abbreviation Description
AACP Asymmetric Authorization Change Protocol
ADCP Authorization Data Change Protocol
ADIP Authorization Data Insertion Protocol
AIK Attestation Identity Key
AMC Audit Monotonic Counter
APIP Time-Phased Implementation Plan
AuthData Authentication Data or Authorization Data, depending on the context
BCD Binary Coded Decimal
BIOS Basic Input/Output System
CA Certification of Authority
CDI Controlled Data Item
CMK Certifiable/Certified Migratable Keys
CRT Chinese Remainder Theorem
CRTM Core Root of Trust Measurement
CTR Counter-mode encryption
DAA Direct Autonomous Attestation
DIR Data Integrity Register
DOS Disk Operating System
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ISO/IEC 11889-1:2009(E)
Abbreviation Description
DSA Digital Signature Algorithm
DSAP Delegate-Specific Authorization Protocol
ECB Electronic Codebook Mode
EK Endorsement Key
ET ExecuteTransport or Entity Type
FIPS Federal Information Processing Standard
GPIO General Purpose I/O
HMAC Hash Message Authentication Code
HW Hardware Interface
IB Internal Base
I/O Input/Output
IV Initialization Vector
KH Key Handle
LEAP Lightweight Extensible Authentication Protocol for wireless computer networks
LK Loaded Key
LOM Limited Operation Mode
LPC Low Pin Count
LSB Least Significant Byte
MA Migration Authority/Authorization
MIDL Microsoft Interface Definition Language
MSA Migration Selection Authority
MSB Most Significant Byte
NV Non-volatile
NVRAM Non-Volatile Random Access Memory
OAEP Optimal Asymmetric Encryption Padding
OEM Original Equipment Manufacturer
OIAP Object-Independent Authorization Protocol
OID Object Identifier
OSAP Object-Specific Authorization Protocol
PCR Platform Configuration Register
PI Personal Information
PII Personally Identifiable Information
POST Power On Self Test
PRIVEK Private Endorsement Key
PRNG Pseudo Random Number Generator
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ISO/IEC 11889-1:2009(E)
Abbreviation Description
PSS Probabilistic Signature Scheme
PUBEK Public Endorsement Key
RNG Random Number Generator
RSA Algorithm for public-key cryptography. The letters R, S, and A represent the initials
of the first public describers of the algorithm.
RTM Release to Manufacturing/Ready to Market
RTR Root of Trust for Reporting
RTS Root of Trust for Storage
SHA Secure Hash Algorithm
SRK Storage Root Key
STF Self Test Failed
TA Time Authority
TBB Threading Building Blocks
TCG Trusted Computing Group
TCV Tick Count Value
TIR Tick Increment Rate
TIS TPM Interface Specification
TNC Trusted Network Connect
TOE Target of Evaluation
TOS Trusted Operating System
TPCA Trusted Platform Computing Alliance
TPM Trusted Platform Module
TPME Trusted Platform Module Entity
TSC Tick Stamp Counter
TSC_ TPM Software Connection, when used as a command prefix
TSN Tick Session Name
TSR Tick Stamp Reset
TSRB TickStampReset for blob
TSS TCG Software Stack
TTP Trusted Third Party/Time-Triggered Protocol
TS Tick Stamp
UTC Universal Time Clock
VPN Virtual Private Network
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ISO/IEC 11889-1:2009(E)
3. The Trusted Platform
Trust in the context of “Trusted Platforms” is the expectation that a device will behave in a particular
manner for a specific purpose.
In Trusted Platforms, Roots of Trust are components that must be trusted because misbehavior may
not be detected. A complete set of Roots of Trust has at least the minimum functionality necessary
to describe the platform characteristics that affect the trustworthiness of the platform.
There are commonly three Roots of Trust in a trusted platform; a root of trust for measurement
(RTM), root of trust for storage (RTS) and root of trust for reporting (RTR). The RTM is a computing
engine capable of making inherently reliable integrity measurements. Typically the normal platform
computing engine, controlled by the core root of trust for measurement (CRTM).
The CRTM is the instructions executed by the platform when it acts as the RTM. The RTM is also
the root of the chain of transitive trust. The RTS is a computing engine capable of maintaining an
accurate summary of values of integrity digests and the sequence of digests. The RTR is a
computing engine capable of reliably reporting information held by the RTS.
Each root is trusted to function correctly without external oversight. Trusting “roots of trust” may be
achieved through a variety of ways but is anticipated to include technical evaluation by competent
experts.
3.1 Trusted Platform Building Block
The Trusted Building Block (TBB) is the parts of the Roots of Trust that do not have shielded
locations. Normally these include just the instructions for the RTM and TPM initialization functions
(reset, etc.). Typically they are platform-specific.
One example of a TBB is the combination of the CRTM, connection of the CRTM storage to a
motherboard, the connection of the TPM to a motherboard, and mechanisms for determining
Physical Presence
The TBB is trusted, meaning it is expected to behave in a way that doesn’t compromise the goals of
trusted platforms.
3.2 The Trust Boundary
The combination of TBB and Roots of Trust form a trust boundary where measurement, storage and
reporting can be accomplished for a minimal configuration. More complex systems may require
measurements be taken by other (optional) ROM code besides the CRTM. For this to occur trust in
other ROM code must be established. This is done by measuring the ROM code prior to transferring
execution control. The TBB should be established such that devices containing other measurement
code do not inadvertently extend the TBB boundary where trustworthiness of the linkages has not
been previously established.
3.3 Transitive Trust
Transitive trust (also known as “Inductive Trust”), is a process where the Root of Trust gives a
trustworthy description of a second group of functions.
Based on this description, an interested entity can determine the trust it is to place in this second
group of functions. If the interested entity determines that the trust level of the second group of
functions is acceptable, the trust boundary is extended from the Root of Trust to include the second
group of functions.
In this case, the process can be iterated. The second group of functions can give a trustworthy
description of the third group of functions, etc. Transitive trust is used to provide a trustworthy
description of platform characteristics, and also to provide evidence that non-migratable keys are
non-migratable
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ISO/IEC 11889-1:2009(E)
3.3.1 Basic Trusted Platform features
A trusted platform should provide at least three basic features:
1. Protected storage
2. Integrity measurement
3. Integrity reporting
All three of these functions are related to attestation, which is the process of vouching for the
accuracy of information. All forms of attestation require reliable evidence of the attesting entity. This
can be provided by shipping TPMs with an embedded key called the Endorsement Key (EK). The
EK is used in a process for the issuance of credentials for another type of key, called an Attestation
Identity Key (AIK). A platform can attest to its description of platform characteristics that affect the
integrity (trustworthiness) of a platform.
External entities can attest to shielded locations, protected capabilities, and Roots of Trust.
Attestation can be understood in four dimensions: Attestation by the TPM, attestation to the
platform, attestation of the platform and authentication of the platform.
• Attestation by the TPM is an operation that provides proof of data known to the TPM. This
is done by digitally signing specific internal TPM data using an Attestation Identity Key (AIK).
The acceptance and validity of both the integrity measurements and the AIK itself are
determined by a verifier.
• Attestation t
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