RFC 5934
Trust Anchor Management Protocol (TAMP)
4. Trust Anchor Management Protocol Messages
TAMP makes use of signed and unsigned messages. The CMS is used in both cases. An object identifier is assigned to each TAMP message type, and this object identifier is used as a content type in the CMS. TAMP specifies eleven message types. The following provides the content type identifier for each TAMP message type, and it indicates whether a digital signature is required. If the following indicates that the TAMP message MUST be signed, then implementations MUST reject a message of that type that is not signed. o The TAMP Status Query message MUST be signed. It uses the following object identifier: { id-tamp 1 }. o The TAMP Status Response message SHOULD be signed. It uses the following object identifier: { id-tamp 2 }. o The Trust Anchor Update message MUST be signed. It uses the following object identifier: { id-tamp 3 }. o The Trust Anchor Update Confirm message SHOULD be signed. It uses the following object identifier: { id-tamp 4 }. o The Apex Trust Anchor Update message MUST be signed. It uses the following object identifier: { id-tamp 5 }.
o The Apex Trust Anchor Update Confirm message SHOULD be signed. It
uses the following object identifier: { id-tamp 6 }.
o The Community Update message MUST be signed. It uses the
following object identifier: { id-tamp 7 }.
o The Community Update Confirm message SHOULD be signed. It uses
the following object identifier: { id-tamp 8 }.
o The Sequence Number Adjust MUST be signed. It uses the following
object identifier: { id-tamp 10 }.
o The Sequence Number Adjust Confirm message SHOULD be signed. It
uses the following object identifier: { id-tamp 11 }.
o The TAMP Error message SHOULD be signed. It uses the following
object identifier: { id-tamp 9 }.
Trust anchor managers generate TAMP Status Query, Trust Anchor
Update, Apex Trust Anchor Update, Community Update, and Sequence
Number Adjust messages. Trust anchor stores generate TAMP Status
Response, Trust Anchor Update Confirm, Apex Trust Anchor Update
Confirm, Community Update Confirm, Sequence Number Adjust Confirm,
and TAMP Error messages.
Support for Trust Anchor Update messages is REQUIRED. Support for
all other message formats is RECOMMENDED. Implementations that
support the HTTP binding described in Appendix C MUST additionally
support Trust Anchor Update Confirm and TAMP Error messages and MAY
support 0 or more of the following pairs of messages: TAMP Status
Query and TAMP Status Query Response; Apex Trust Anchor Update and
Apex Trust Anchor Update Confirm; Community Update and Community
Update Confirm; Sequence Number Adjust and Sequence Number Adjust
Confirm. Implementations that operate in a disconnected manner MUST
NOT assume a response will be received from each consumer of a TAMP
message.
A typical interaction between a trust anchor manager and a trust
anchor store will follow the message flow shown in Figure 1. Figure
1 does not illustrate a flow where an error occurs.
+---------+ +----------+ | | Trust Anchor Status Query | | | |------------------------------->| | | | | | | | Trust Anchor Status Response | | | Trust |<-------------------------------| Trust | | Anchor | | Anchor | | Manager | Trust Anchor Update | Store | | |------------------------------->| | | | | | | | Trust Anchor Update Confirm | | | |<-------------------------------| | | | | | +---------+ +----------+ Figure 1. Typical TAMP Message Flow Each TAMP query and update message includes an indication of the type of response that is desired. The response can either be terse or verbose. All trust anchor stores MUST support both the terse and verbose responses and SHOULD generate a response of the type indicated in the corresponding request. TAMP response processors MUST support processing of both terse and verbose responses. Trust anchor stores SHOULD be able to process and properly act upon the valid payload of the TAMP Status Query message, the Trust Anchor Update message, the Apex Trust Anchor Update message, and the Sequence Number Adjust message. TAMP implementations MAY also process and act upon the valid payload of the Community Update message. TAMP implementations SHOULD support generation of the TAMP Status Response message, the Trust Anchor Update Confirm message, the Apex Trust Anchor Update Confirm message, the Sequence Number Adjust Confirm message, and the TAMP Error message. If a TAMP implementation supports the Community Update message, then generation of Community Update Confirm messages SHOULD also be supported.4.1. TAMP Status Query
The TAMP Status Query message is used to request information about the trust anchors that are currently installed in a trust anchor store, and for the list of communities to which the store belongs. The TAMP Status Query message MUST be signed. For the query message to be valid, the trust anchor store MUST be an intended recipient of the query; the sequence number checking described in Section 6 MUST be successful when the TAMP message signer is a trust anchor; and the digital signature MUST be validated by the apex trust anchor
operational public key, an authorized management trust anchor, or via
an authorized X.509 certification path originating with such a trust
anchor.
If the digital signature on the TAMP Status Query message is valid,
sequence number checking is successful, the signer is authorized, and
the trust anchor store is an intended recipient of the TAMP message,
then a TAMP Status Response message SHOULD be returned. If a TAMP
Status Response message is not returned, then a TAMP Error message
SHOULD be returned.
The TAMP Status Query content type has the following syntax:
CONTENT-TYPE ::= TYPE-IDENTIFIER
tamp-status-query CONTENT-TYPE ::=
{ TAMPStatusQuery IDENTIFIED BY id-ct-TAMP-statusQuery }
id-ct-TAMP-statusQuery OBJECT IDENTIFIER ::= { id-tamp 1 }
TAMPStatusQuery ::= SEQUENCE {
Version [0] TAMPVersion DEFAULT v2,
terse [1] TerseOrVerbose DEFAULT verbose,
query TAMPMsgRef }
TAMPVersion ::= INTEGER { v1(1), v2(2) }
TerseOrVerbose ::= ENUMERATED { terse(1), verbose(2) }
TAMPMsgRef ::= SEQUENCE {
target TargetIdentifier,
seqNum SeqNumber }
SeqNumber ::= INTEGER (0..9223372036854775807)
TargetIdentifier ::= CHOICE {
hwModules [1] HardwareModuleIdentifierList,
communities [2] CommunityIdentifierList,
allModules [3] NULL,
uri [4] IA5String,
otherName [5] AnotherName }
HardwareModuleIdentifierList ::= SEQUENCE SIZE (1..MAX) OF
HardwareModules
HardwareModules ::= SEQUENCE {
hwType OBJECT IDENTIFIER,
hwSerialEntries SEQUENCE SIZE (1..MAX) OF HardwareSerialEntry }
HardwareSerialEntry ::= CHOICE {
all NULL,
single OCTET STRING,
block SEQUENCE {
low OCTET STRING,
high OCTET STRING } }
CommunityIdentifierList ::= SEQUENCE SIZE (0..MAX) OF Community
Community ::= OBJECT IDENTIFIER
The fields of TAMPStatusQuery are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o terse indicates the type of response that is desired. A terse
response is indicated by a value of 1, and a verbose response is
indicated by a value of 2, which is omitted during encoding since
it is the default value.
o query contains two items: the target and the seqNum. target
identifies the target(s) of the query message. seqNum is a
single-use value that will be used to match the TAMP Status Query
message with the TAMP Status Response message. The sequence
number is also used to detect TAMP message replay. The sequence
number processing described in Section 6 MUST successfully
complete before a response is returned.
The fields of TAMPMsgRef are used as follows:
o target identifies the target(s) of the query. Several
alternatives for naming a target are provided. To identify a
cryptographic module, a combination of a cryptographic type and
serial number are used. The cryptographic type is represented as
an ASN.1 object identifier, and the unique serial number is
represented as a string of octets. To facilitate compact
representation of serial numbers, a contiguous block can be
specified by the lowest included serial number and the highest
included serial number. When present, the high and low octet
strings MUST have the same length. The
HardwareModuleIdentifierList sequence MUST NOT contain duplicate
hwType values, so that each member of the sequence names all of
the cryptographic modules of this type. Object identifiers are
also used to identify communities of trust anchor stores. A
sequence of these object identifiers is used if more than one
community is the target of the message. A trust anchor store is
considered a target if it is a member of any of the listed
communities. An explicit NULL value is used to identify all
modules that consider the signer of the TAMP message to be an
authorized source for that message type. The uri field can be
used to identify a target, i.e., a trust anchor store, using a
Uniform Resource Identifier [RFC3986]. Additional name types are
supported via the otherName field, which is of type AnotherName.
AnotherName is defined in [RFC5280]. The format and semantics of
the name are indicated through the OBJECT IDENTIFIER in the type-
id field. The name itself is conveyed as a value field in
otherName. Implementations MUST support the allModules option and
SHOULD support all TargetIdentifier options.
o seqNum contains a single-use value that will be used to match the
TAMP Status Query message with the successful TAMP Status Response
message. The sequence number processing described in Section 6
MUST successfully complete before a response is returned.
To determine whether a particular cryptographic module serial number
is considered part of a specified block, all of the following
conditions MUST be met. First, the cryptographic module serial
number MUST be the same length as both the high and low octet
strings. Second, the cryptographic module serial number MUST be
greater than or equal to the low octet string. Third, the
cryptographic module serial number MUST be less than or equal to the
high octet string.
One octet string is equal to another if they are of the same length
and are the same at each octet position. An octet string, S1, is
greater than another, S2, where S1 and S2 have the same length, if
and only if S1 and S2 have different octets in one or more positions,
and in the first such position, the octet in S1 is greater than that
in S2, considering the octets as unsigned binary numbers. Note that
these octet string comparison definitions are consistent with those
in clause 6 of [X.690].
4.2. TAMP Status Query Response
The TAMP Status Response message is a reply by a trust anchor store
to a valid TAMP Status Query message. The TAMP Status Response
message provides information about the trust anchors that are
currently installed in the trust anchor store and the list of
communities to which the trust anchor store belongs, if any. The
TAMP Status Response message MAY be signed or unsigned. A TAMP
Status Response message MUST be signed if the implementation is
capable of signing it.
The TAMP Status Response content type has the following syntax:
tamp-status-response CONTENT-TYPE ::=
{ TAMPStatusResponse IDENTIFIED BY id-ct-TAMP-statusResponse }
id-ct-TAMP-statusResponse OBJECT IDENTIFIER ::= { id-tamp 2 }
TAMPStatusResponse ::= SEQUENCE {
version [0] TAMPVersion DEFAULT v2,
query TAMPMsgRef,
response StatusResponse,
usesApex BOOLEAN DEFAULT TRUE }
StatusResponse ::= CHOICE {
terseResponse [0] TerseStatusResponse,
verboseResponse [1] VerboseStatusResponse }
TerseStatusResponse ::= SEQUENCE {
taKeyIds KeyIdentifiers,
communities CommunityIdentifierList OPTIONAL }
KeyIdentifiers ::= SEQUENCE SIZE (1..MAX) OF KeyIdentifier
VerboseStatusResponse ::= SEQUENCE {
taInfo TrustAnchorChoiceList,
continPubKeyDecryptAlg [0] AlgorithmIdentifier OPTIONAL,
communities [1] CommunityIdentifierList OPTIONAL,
tampSeqNumbers [2] TAMPSequenceNumbers OPTIONAL }
TrustAnchorChoiceList ::= SEQUENCE SIZE (1..MAX) OF
TrustAnchorChoice
TAMPSequenceNumbers ::= SEQUENCE SIZE (1..MAX) OF TAMPSequenceNumber
TAMPSequenceNumber ::= SEQUENCE {
keyId KeyIdentifier,
seqNumber SeqNumber }
The fields of TAMPStatusResponse are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o query identifies the TAMPStatusQuery to which the trust anchor
store is responding. The query structure repeats the TAMPMsgRef
from the TAMP Status Query message (see Section 4.1). The
sequence number processing described in Section 6 MUST
successfully complete before any response is returned.
o response contains either a terse response or a verbose response.
The terse response is represented by TerseStatusResponse, and the
verbose response is represented by VerboseStatusResponse.
o usesApex is a Boolean value that indicates whether the first item
in the TerseStatusResponse.taKeyIds or
VerboseStatusResponse.taInfo field identifies the apex TA.
The fields of TerseStatusResponse are used as follows:
o taKeyIds contains a sequence of key identifiers. Each trust
anchor contained in the trust anchor store is represented by one
key identifier. When TAMPStatusResponse.usesApex is TRUE, the
apex trust anchor is represented by the first key identifier in
the sequence, which contains the key identifier of the operational
public key.
o communities is OPTIONAL. When present, it contains a sequence of
object identifiers. Each object identifier names one community to
which this trust anchor store belongs. When the trust anchor
store belongs to no communities, this field is omitted.
The fields of VerboseStatusResponse are used as follows:
o taInfo contains a sequence of TrustAnchorChoice structures. One
entry in the sequence is provided for each trust anchor contained
in the trust anchor store. When TAMPStatusResponse.usesApex is
TRUE, the apex trust anchor is the first trust anchor in the
sequence.
o continPubKeyDecryptAlg is OPTIONAL. When present, it indicates
the decryption algorithm needed to decrypt the currently installed
apex trust anchor contingency public key, if a contingency key is
associated with the apex trust anchor. When present,
TAMPStatusResponse.usesApex MUST be TRUE.
o communities is OPTIONAL. When present, it contains a sequence of
object identifiers. Each object identifier names one community to
which this trust anchor store belongs. When the trust anchor
store belongs to no communities, this field is omitted.
o tampSeqNumbers is OPTIONAL. When present, it is used to indicate
the currently held sequence number for each trust anchor
authorized to sign TAMP messages. The keyId field identifies the
trust anchor, and the seqNumber field provides the current
sequence number associated with the trust anchor.
4.3. Trust Anchor Update
The Trust Anchor Update message is used to add, remove, and change management and identity trust anchors. The Trust Anchor Update message cannot be used to update the apex trust anchor. The Trust Anchor Update message MUST be signed. For a Trust Anchor Update message to be valid, the trust anchor store MUST be an intended recipient of the update; the sequence number checking described in Section 6 MUST be successful when the TAMP message signer is a trust anchor; and the digital signature MUST be validated using the apex trust anchor operational public key, an authorized management trust anchor, or via an authorized X.509 certification path originating with such a trust anchor. If the digital signature on the Trust Anchor Update message is valid, sequence number checking is successful, the signer is authorized, and the trust anchor store is an intended recipient of the TAMP message, then the trust anchor store MUST perform the specified updates and return a Trust Anchor Update Confirm message. If a Trust Anchor Update Confirm message is not returned, then a TAMP Error message SHOULD be returned. The Trust Anchor Update content type has the following syntax: tamp-update CONTENT-TYPE ::= { TAMPUpdate IDENTIFIED BY id-ct-TAMP-update } id-ct-TAMP-update OBJECT IDENTIFIER ::= { id-tamp 3 } TAMPUpdate ::= SEQUENCE { version [0] TAMPVersion DEFAULT v2, terse [1] TerseOrVerbose DEFAULT verbose, msgRef TAMPMsgRef, updates SEQUENCE SIZE (1..MAX) OF TrustAnchorUpdate, tampSeqNumbers [2]TAMPSequenceNumbers OPTIONAL } TrustAnchorUpdate ::= CHOICE { add [1] TrustAnchorChoice, remove [2] SubjectPublicKeyInfo, change [3] EXPLICIT TrustAnchorChangeInfoChoice } TrustAnchorChangeInfoChoice ::= CHOICE { tbsCertChange [0] TBSCertificateChangeInfo, taChange [1] TrustAnchorChangeInfo }
TBSCertificateChangeInfo ::= SEQUENCE {
serialNumber CertificateSerialNumber OPTIONAL,
signature [0] AlgorithmIdentifier OPTIONAL,
issuer [1] Name OPTIONAL,
validity [2] Validity OPTIONAL,
subject [3] Name OPTIONAL,
subjectPublicKeyInfo [4] SubjectPublicKeyInfo,
exts [5] EXPLICIT Extensions OPTIONAL }
TrustAnchorChangeInfo ::= SEQUENCE {
pubKey SubjectPublicKeyInfo,
keyId KeyIdentifier OPTIONAL,
taTitle TrustAnchorTitle OPTIONAL,
certPath CertPathControls OPTIONAL,
exts [1] Extensions OPTIONAL }
The fields of TAMPUpdate are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o terse indicates the type of response that is desired. A terse
response is indicated by a value of 1, and a verbose response is
indicated by a value of 2, which is omitted during encoding since
it is the default value.
o msgRef contains two items: the target and the seqNum. target
identifies the target(s) of the update message. The
TargetIdentifier syntax is described in Section 4.1. seqNum is a
single-use value that will be used to match the Trust Anchor
Update message with the Trust Anchor Update Confirm message. The
sequence number is also used to detect TAMP message replay. The
sequence number processing described in Section 6 MUST
successfully complete before any of the updates are processed.
o updates contains a sequence of updates, which are used to add,
remove, and change management or identity trust anchors. Each
entry in the sequence represents one of these actions, and is
indicated by an instance of TrustAnchorUpdate. The actions are a
batch of updates that MUST be processed in the order that they
appear, but each of the updates is processed independently. Each
of the updates MUST satisfy the subordination checks described in
Section 7. Even if one or more of the updates fail, then the
remaining updates MUST be processed. These updates MUST NOT make
any changes to the apex trust anchor.
o tampSeqNumbers MAY be included to provide the initial or new
sequence numbers for trust anchors added or changed by the updates
field. Elements included in the tampSeqNumbers field that do not
correspond to an element in the updates field are ignored.
Elements included in the tampSeqNumbers field that do correspond
to an element in the updates field and contain a sequence number
less than or equal to the most recently stored sequence number for
the trust anchor are ignored. Elements included in the
tampSeqNumbers field that do correspond to an element in the
updates field and contain a sequence number greater than the most
recently stored sequence number for the indicated trust anchor are
processed by setting the stored sequence number for the trust
anchor equal to the new value.
The TrustAnchorUpdate is a choice of three structures, and each
alternative represents one of the three possible actions: add,
remove, and change. A description of the syntax associated with each
of these actions follows:
o add is used to insert a new management or identity trust anchor
into the trust anchor store. The TrustAnchorChoice structure is
used to provide the trusted public key and all of the information
associated with it. However, the action MUST fail with the error
code notAuthorized if the subordination checks described in
Section 7 are not satisfied. See Section 3 for a discussion of
the TrustAnchorChoice structure. The apex trust anchor cannot be
introduced into a trust anchor store using this action; therefore,
the id-pe-wrappedApexContinKey MUST NOT be present in the
extensions field. The constraints of the existing trust anchors
are unchanged by this action. An attempt to add a management or
identity trust anchor that is already in place with the same
values for every field in the TrustAnchorChoice structure MUST be
treated as a successful addition. An attempt to add a management
or identity trust anchor that is already present with the same
pubKey values, but with different values for any of the fields in
the TrustAnchorChoice structure, MUST fail with the error code
improperTAAddition. This means a trust anchor may not be added
twice using different TrustAnchorChoice options. If a different
format is desired, the existing trust anchor must be removed and
the new format added.
o remove is used to delete an existing management or identity trust
anchor from the trust anchor store, including the deletion of the
management trust anchor associated with the TAMP message signer.
However, the action MUST fail with the error code notAuthorized if
the subordination checks described in Section 7 are not satisfied.
The public key contained in SubjectPublicKeyInfo names the
management or identity trust anchor to be deleted. An attempt to
delete a trust anchor that is not present MUST be treated as a
successful deletion. The constraints of the deleted trust anchor
are not distributed to other trust anchors in any manner. The
apex trust anchor cannot be removed using this action, which
ensures that this action cannot place the trust anchor store in an
unrecoverable configuration.
o change is used to update the information associated with an
existing management or identity trust anchor in the trust anchor
store. Attempts to change a trust anchor added as a Certificate
MUST fail with the error code improperTAChange. The public key
contained in the SubjectPublicKeyInfo field of
TrustAnchorChangeInfo or in the subjectPublicKeyInfo field of a
TBSCertificateChangeInfo names the to-be-updated trust anchor.
However, the action MUST fail with the error code notAuthorized if
the subordination checks described in Section 7 are not satisfied.
An attempt to change a trust anchor that is not present MUST
result in a failure with the trustAnchorNotFound status code. The
TrustAnchorChangeInfo structure or the TBSCertificateChangeInfo
structure is used to provide the revised configuration of the
management or identity trust anchor. If the update fails for any
reason, then the original trust anchor configuration MUST be
preserved. The apex trust anchor information cannot be changed
using this action. Attempts to change a trust anchor added as a
TBSCertificate using a TrustAnchorChangeInfo MUST fail with an
improperTAChange error. Attempts to change a trust anchor added
as a TrustAnchorInfo using a TBSCertificateChangeInfo MUST fail
with an improperTAChange error.
The fields of TrustAnchorChangeInfo are used as follows:
o pubKey contains the algorithm identifier and the public key of the
management or identity trust anchor. It is used to locate the
to-be-updated trust anchor in the trust anchor store.
o keyId is OPTIONAL, and when present, it contains the public key
identifier of the trust anchor public key, which is contained in
the pubKey field. If this field is not present, then the public
key identifier remains unchanged. If this field is present, the
provided public key identifier replaces the previous one.
o taTitle is OPTIONAL, and when present, it provides a human
readable name for the management or identity trust anchor. When
absent in a change trust anchor update, any title that was
previously associated with the trust anchor is removed.
Similarly, when present in a change trust anchor update, the title
in the message is associated with the trust anchor. If a previous
title was associated with the trust anchor, then the title is
replaced. If a title was not previously associated with the trust
anchor, then the title from the update message is added.
o certPath is OPTIONAL, and when present, it provides the controls
needed to construct and validate an X.509 certification path.
When absent in a change trust anchor update, any controls that
were previously associated with the management or identity trust
anchor are removed, which means that delegation is no longer
permitted. Similarly, when present in a change trust anchor
update, the controls in the message are associated with the
management or identity trust anchor. If previous controls,
including the trust anchor distinguished name, were associated
with the trust anchor, then the controls are replaced, which means
that delegation continues to be supported, but that different
certification paths will be valid. If controls were not
previously associated with the management or identity trust
anchor, then the controls from the update message are added, which
enables delegation. The syntax and semantics of CertPathControls
are discussed in [RFC5914].
o exts is OPTIONAL, and when present, it provides the extensions
values that are associated with the trust anchor. When absent in
a change trust anchor update, any extensions that were previously
associated with the trust anchor are removed. Similarly, when
present in a change trust anchor update, the extensions in the
message are associated with the trust anchor. Any extensions
previously associated with the trust anchor are replaced or
removed.
The fields of TBSCertificateChangeInfo are used to alter the fields
within a TBSCertificate structure. TBSCertificate is described in
[RFC5280]. For all fields except exts, if the field is absent in a
change trust anchor update, then any previous value associated with a
trust anchor is unchanged. For the exts field, if the field is
absent in a change trust anchor update, then any previous value
associated with a trust anchor is removed. For all fields, if the
field is present in a change trust anchor update, then any previous
value associated with a trust anchor is replaced with the value from
the update message.
4.3.1. Trust Anchor List
[RFC5914] defines the TrustAnchorList structure to convey a list of
trust anchors. TAMP implementations MAY process TrustAnchorList
objects (with eContentType (or contentType) using the id-ct-
trustAnchorList OID defined in [RFC5914]) as equivalent to TAMPUpdate
objects with terse set to terse, msgRef set to allModules (with a suitable sequence number), and all elements within the list contained within the add field. This alternative to TrustAnchorUpdate is provided for implementations that perform integrity and authorization checks out-of-band as a simple means of transferring trust anchors from one trust anchor store to another. It does not provide a means of removing or changing trust anchors and has no HTTP binding.4.4. Trust Anchor Update Confirm
The Trust Anchor Update Confirm message is a reply by a trust anchor store to a valid Trust Anchor Update message. The Trust Anchor Update Confirm message provides success and failure information for each of the requested updates. The Trust Anchor Update Confirm message MAY be signed or unsigned. A Trust Anchor Update Confirm message MUST be signed if the implementation is capable of signing it. The Trust Anchor Update Confirm content type has the following syntax: tamp-update-confirm CONTENT-TYPE ::= { TAMPUpdateConfirm IDENTIFIED BY id-ct-TAMP-updateConfirm } id-ct-TAMP-updateConfirm OBJECT IDENTIFIER ::= { id-tamp 4 } TAMPUpdateConfirm ::= SEQUENCE { version [0] TAMPVersion DEFAULT v2, update TAMPMsgRef, confirm UpdateConfirm } UpdateConfirm ::= CHOICE { terseConfirm [0] TerseUpdateConfirm, verboseConfirm [1] VerboseUpdateConfirm } TerseUpdateConfirm ::= StatusCodeList StatusCodeList ::= SEQUENCE SIZE (1..MAX) OF StatusCode VerboseUpdateConfirm ::= SEQUENCE { status StatusCodeList, taInfo TrustAnchorChoiceList, tampSeqNumbers TAMPSequenceNumbers OPTIONAL, usesApex BOOLEAN DEFAULT TRUE }
The fields of TAMPUpdateConfirm are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o update identifies the TAMPUpdate message to which the trust anchor
store is responding. The update structure repeats the TAMPMsgRef
from the Trust Anchor Update message (see Section 4.3). The
sequence number processing described in Section 6 MUST
successfully complete before any of the updates are processed.
o confirm contains either a terse update confirmation or a verbose
update confirmation. The terse update confirmation is represented
by TerseUpdateConfirm, and the verbose response is represented by
VerboseUpdateConfirm.
The TerseUpdateConfirm contains a sequence of status codes, one for
each TrustAnchorUpdate structure in the Trust Anchor Update message.
The status codes MUST appear in the same order as the
TrustAnchorUpdate structures to which they apply, and the number of
elements in the status code list MUST be the same as the number of
elements in the trust anchor update list. Each of the status codes
is discussed in Section 5.
The fields of VerboseUpdateConfirm are used as follows:
o status contains a sequence of status codes, one for each
TrustAnchorUpdate structure in the Trust Anchor Update message.
The status codes appear in the same order as the TrustAnchorUpdate
structures to which they apply, and the number of elements in the
status code list MUST be the same as the number of elements in the
trust anchor update list. Each of the status codes is discussed
in Section 5.
o taInfo contains a sequence of TrustAnchorChoice structures. One
entry in the sequence is provided for each trust anchor contained
in the trust anchor store. These represent the state of the trust
anchors after the updates have been processed. When usesApex is
true, the apex trust anchor is the first trust anchor in the
sequence.
o tampSeqNumbers is used to indicate the currently held sequence
number for each trust anchor authorized to sign TAMP messages.
The keyId field identifies the trust anchor, and the seqNumber
field provides the current sequence number associated with the
trust anchor.
o usesApex is a Boolean value that indicates whether the first item
in the taInfo field identifies the apex TA.
4.5. Apex Trust Anchor Update
The Apex Trust Anchor Update message replaces the operational public
key and, optionally, the contingency public key associated with the
apex trust anchor. Each trust anchor store has exactly one apex
trust anchor. No constraints are associated with the apex trust
anchor. The public key identifier of the operational public key is
used to identify the apex trust anchor in subsequent TAMP messages.
The digital signature on the Apex Trust Anchor Update message is
validated with either the current operational public key or the
current contingency public key. For the Apex Trust Anchor Update
message that is validated with the operational public key to be
valid, the trust anchor store MUST be a target of the update, the
sequence number MUST be larger than the most recently stored sequence
number for the operational public key, and the digital signature MUST
be validated directly with the operational public key. That is, no
delegation via a certification path is permitted. For the Apex Trust
Anchor Update message that is validated with the contingency public
key to be valid, the trust anchor store MUST be a target of the
update, the provided decryption key MUST properly decrypt the
contingency public key, and the digital signature MUST be validated
directly with the decrypted contingency public key. Again, no
delegation via a certification path is permitted.
If the Apex Trust Anchor Update message is validated using the
operational public key, then sequence number processing is handled
normally, as described in Section 6. If the Apex Trust Anchor Update
message is validated using the contingency public key, then the
TAMPMsgRef sequence number MUST contain a zero value. A sequence
number for subsequent messages that will be validated with the new
operational public key can optionally be provided. If no value is
provided, then the trust anchor store MUST be prepared to accept any
sequence number in the next TAMP message validated with the newly
installed apex trust anchor operational public key. If the Apex
Trust Anchor Update message is valid and the clearTrustAnchors flag
is set to TRUE, then all of the management and identity trust anchors
stored in the trust anchor store MUST be deleted. That is, the new
apex trust anchor MUST be the only trust anchor remaining in the
trust anchor store. If the Apex Trust Anchor Update message is valid
and the clearCommunities flag is set to TRUE, then all community
identifiers stored in the trust anchor store MUST be deleted.
The SignedData structure includes a SignerInfo.sid value, and it
identifies the apex trust anchor public key that will be used to
validate the digital signature on this TAMP message. The public key
identifier for the operational public key is known in advance, and it
is stored as part of the apex trust anchor. The public key
identifier for the contingency public key is not known in advance;
however, the presence of the unsigned attribute containing the
symmetric key needed to decrypt the contingency public key
unambiguously indicates that the TAMP message signer used the
contingency private key to sign the Apex Trust Anchor Update message.
If the digital signature on the Apex Trust Anchor Update message is
valid using either the apex trust anchor operational public key or
the apex trust anchor contingency public key, sequence number
checking is successful, and the trust anchor store is an intended
recipient of the TAMP message, then the trust anchor store MUST
update the apex trust anchor and return an Apex Trust Anchor Update
Confirm message. If an Apex Trust Anchor Update Confirm message is
not returned, then a TAMP Error message SHOULD be returned. Note
that the sequence number MUST be zero if the Apex Trust Anchor Update
message is validated with the apex trust anchor contingency public
key.
The Apex Trust Anchor Update content type has the following syntax:
tamp-apex-update CONTENT-TYPE ::=
{ TAMPApexUpdate IDENTIFIED BY id-ct-TAMP-apexUpdate }
id-ct-TAMP-apexUpdate OBJECT IDENTIFIER ::= { id-tamp 5 }
TAMPApexUpdate ::= SEQUENCE {
version [0] TAMPVersion DEFAULT v2,
terse [1] TerseOrVerbose DEFAULT verbose,
msgRef TAMPMsgRef,
clearTrustAnchors BOOLEAN,
clearCommunities BOOLEAN,
seqNumber SeqNumber OPTIONAL,
apexTA TrustAnchorChoice }
The fields of TAMPApexUpdate are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o terse indicates the type of response that is desired. A terse
response is indicated by a value of 1, and a verbose response is
indicated by a value of 2, which is omitted during encoding since
it is the default value.
o msgRef contains two items: the target and the seqNum. target
identifies the target(s) of the Apex Trust Anchor Update message.
The TargetIdentifier syntax as described in Section 4.1 is used.
seqNum is a single-use value that will be used to match the Apex
Trust Anchor Update message with the Apex Trust Anchor Update
Confirm message. The sequence number is also used to detect TAMP
message replay if the message is validated with the apex trust
anchor operational public key. The sequence number processing
described in Section 6 MUST successfully complete before any
action is taken. However, seqNum MUST contain a zero value if the
message is validated with the apex trust anchor contingency
public key.
o clearTrustAnchors is a Boolean. If the value is set to TRUE, then
all of the management and identity trust anchors stored in the
trust anchor store MUST be deleted, leaving the newly installed
apex trust anchor as the only trust anchor in the trust anchor
store. If the value is set to FALSE, the other trust anchors MUST
NOT be changed.
o clearCommunities is a Boolean. If the value is set to TRUE, then
all of the community identifiers stored in the trust anchor store
MUST be deleted, leaving none. If the value is set to FALSE, the
list of community identifiers MUST NOT be changed.
o seqNumber is OPTIONAL, and when present, it provides the initial
sequence number for the apex trust anchor. If seqNumber is
absent, the trust anchor store is prepared to accept any sequence
number value for the apex trust anchor operational public key.
o apexTA provides the information for the replacement apex trust
anchor. The TrustAnchorChoice structure is used to provide the
trusted public key and all of the information associated with it.
The pubKey, keyId, taTitle, certPath, and exts fields apply to the
operational public key of the apex trust anchor. The
ApexTrustAnchorInfo certificate extension MAY appear as an
extension. Section 9 describes the WrappedApexContingencyKey
certificate extension.
4.6. Apex Trust Anchor Update Confirm
The Apex Trust Anchor Update Confirm message is a reply by a trust
anchor store to a valid Apex Trust Anchor Update message. The Apex
Trust Anchor Update Confirm message provides success or failure
information for the apex trust anchor update. The Apex Trust Anchor
Update Confirm message MAY be signed or unsigned. An Apex Trust
Anchor Update Confirm message MUST be signed if the trust anchor
store is capable of signing it.
The Apex Trust Anchor Update Confirm content type has the following
syntax:
tamp-apex-update-confirm CONTENT-TYPE ::=
{ TAMPApexUpdateConfirm IDENTIFIED BY
id-ct-TAMP-apexUpdateConfirm }
id-ct-TAMP-apexUpdateConfirm OBJECT IDENTIFIER ::= { id-tamp 6 }
TAMPApexUpdateConfirm ::= SEQUENCE {
version [0] TAMPVersion DEFAULT v2,
apexReplace TAMPMsgRef,
apexConfirm ApexUpdateConfirm }
ApexUpdateConfirm ::= CHOICE {
terseApexConfirm [0] TerseApexUpdateConfirm,
verboseApexConfirm [1] VerboseApexUpdateConfirm }
TerseApexUpdateConfirm ::= StatusCode
VerboseApexUpdateConfirm ::= SEQUENCE {
status StatusCode,
taInfo TrustAnchorChoiceList,
communities [0] CommunityIdentifierList OPTIONAL,
tampSeqNumbers [1] TAMPSequenceNumbers OPTIONAL }
The fields of TAMPApexUpdateConfirm are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o apexReplace identifies the Apex Trust Anchor Update message to
which the trust anchor store is responding. The apexReplace
structure repeats the TAMPMsgRef from the beginning of the Apex
Trust Anchor Update message (see Section 4.5). When the Apex
Trust Anchor Update message is validated with the operational
public key, the sequence number processing described in Section 6
MUST successfully complete before an Apex Trust Anchor Update
Confirm message is generated. When the Apex Trust Anchor Update
message is validated with the contingency public key, normal
sequence number processing is ignored, but the seqNum MUST be
zero.
o apexConfirm contains either a terse update confirmation or a
verbose update confirmation. The terse update confirmation is
represented by TerseApexUpdateConfirm, and the verbose response is
represented by VerboseApexUpdateConfirm.
The TerseApexUpdateConfirm contains a single status code, indicating the success or failure of the apex trust anchor update. If the apex trust anchor update failed, then the status code provides the reason for the failure. Each of the status codes is discussed in Section 5. The fields of VerboseApexUpdateConfirm are used as follows: o status contains a single status code, indicating the success or failure of the apex trust anchor update. If the apex trust anchor update failed, then the status code provides the reason for the failure. Each of the status codes is discussed in Section 5. o taInfo contains a sequence of TrustAnchorChoice structures. One entry in the sequence is provided for each trust anchor contained in the trust anchor store. These represent the state of the trust anchors after the apex trust anchor update has been processed. See [RFC5914] for a description of the TrustAnchorInfo structure. The apex trust anchor is the first trust anchor in the sequence. o communities is OPTIONAL. When present, it contains a sequence of object identifiers. Each object identifier names one community to which this trust anchor store belongs. When the trust anchor store belongs to no communities, this field is omitted. o tampSeqNumbers is used to indicate the currently held sequence number for each trust anchor authorized to sign TAMP messages. The keyId field identifies the trust anchor, and the seqNumber field provides the current sequence number associated with the trust anchor.4.7. Community Update
The trust anchor store maintains a list of identifiers for the communities of which it is a member. The Community Update message can be used to remove or add community identifiers from this list. The Community Update message MUST be signed. For the Community Update message to be valid, the trust anchor store MUST be a target of the update; the sequence number checking described in Section 6 MUST be successful when the TAMP message signer is a trust anchor; and the digital signature MUST be validated by the apex trust anchor operational public key, an authorized management trust anchor, or via an authorized X.509 certification path originating with such a trust anchor. If the trust anchor store supports the Community Update message, the digital signature on the Community Update message is valid, sequence number checking is successful, the signer is authorized, and the trust anchor store is an intended recipient of the TAMP message, then
the trust anchor store MUST make the specified updates and return a
Community Update Confirm message. If a Community Update Confirm
message is not returned, then a TAMP Error message SHOULD be
returned.
The Community Update message contains a batch of updates, and all of
the updates MUST be accepted for the trust anchor store to return a
successful Community Update Confirm message. The remove updates, if
present, MUST be processed before the add updates. Where remove is
present with an empty list, all community identifiers MUST be
removed. This approach prevents community identifiers that are
intended to be mutually exclusive from being installed by a
successful addition and a failed removal. Where add is present, at
least one community identifier MUST appear in the list.
The Community Update content type has the following syntax:
tamp-community-update CONTENT-TYPE ::=
{ TAMPCommunityUpdate IDENTIFIED BY id-ct-TAMP-communityUpdate }
id-ct-TAMP-communityUpdate OBJECT IDENTIFIER ::= { id-tamp 7 }
TAMPCommunityUpdate ::= SEQUENCE {
version [0] TAMPVersion DEFAULT v2,
terse [1] TerseOrVerbose DEFAULT verbose,
msgRef TAMPMsgRef,
updates CommunityUpdates }
CommunityUpdates ::= SEQUENCE {
remove [1] CommunityIdentifierList OPTIONAL,
add [2] CommunityIdentifierList OPTIONAL }
-- At least one MUST be present
The fields of TAMPCommunityUpdate are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o terse indicates the type of response that is desired. A terse
response is indicated by a value of 1, and a verbose response is
indicated by a value of 2, which is omitted during encoding since
it is the default value.
o msgRef contains two items: the target and the seqNum. target
identifies the target(s) of the update message. The
TargetIdentifier syntax as described in Section 4.1 is used.
seqNum is a single-use value that will be used to match the
Community Update message with the Community Update Confirm
message. The sequence number is also used to detect TAMP message
replay. The sequence number processing described in Section 6
MUST successfully complete before any of the updates are
processed.
o updates contains a sequence of community identifiers to be removed
and a sequence of community identifiers to be added. These are
represented by the CommunityUpdates structure.
The CommunityUpdates is a sequence of two OPTIONAL sequences, but at
least one of these sequences MUST be present. The first sequence
contains community identifiers to be removed, and if there are none,
it is absent. Where remove is present with an empty list, all
community identifiers MUST be removed. The second sequence contains
community identifiers to be added, and if there are none, it is
absent. The remove updates, if present, MUST be processed before the
add updates. An error is generated if any of the requested removals
or additions cannot be accomplished. However, requests to remove
community identifiers that are not present are treated as successful
removals. Likewise, requests to add community identifiers that are
already present are treated as successful additions. If an error is
generated, the trust anchor store community list MUST NOT be changed.
A description of the syntax associated with each of these actions
follows:
o remove is used to remove one, multiple, or all community
identifiers from the trust anchor store.
o add is used to insert one or more new community identifiers into
the trust anchor store.
4.8. Community Update Confirm
The Community Update Confirm message is a reply by a trust anchor
store to a valid Community Update message. The Community Update
Confirm message provides success or failure information for the
requested updates. Success is returned only if the whole batch of
updates is successfully processed. If any of the requested updates
cannot be performed, then a failure is indicated, and the set of
community identifiers stored in the trust anchor store is unchanged.
The Community Update Confirm message MAY be signed or unsigned. A
Community Update Confirm message MUST be signed if the trust anchor
store is capable of signing it.
The Community Update Confirm content type has the following syntax:
tamp-community-update-confirm CONTENT-TYPE ::=
{ TAMPCommunityUpdateConfirm IDENTIFIED BY
id-ct-TAMP-communityUpdateConfirm }
id-ct-TAMP-communityUpdateConfirm OBJECT IDENTIFIER ::=
{ id-tamp 8 }
TAMPCommunityUpdateConfirm ::= SEQUENCE {
version [0] TAMPVersion DEFAULT v2,
update TAMPMsgRef,
commConfirm CommunityConfirm }
CommunityConfirm ::= CHOICE {
terseCommConfirm [0] TerseCommunityConfirm,
verboseCommConfirm [1] VerboseCommunityConfirm }
TerseCommunityConfirm ::= StatusCode
VerboseCommunityConfirm ::= SEQUENCE {
status StatusCode,
communities CommunityIdentifierList OPTIONAL }
The fields of TAMPCommunityUpdateConfirm are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o update identifies the Community Update message to which the trust
anchor store is responding. The update structure repeats the
TAMPMsgRef from the Community Update message (see Section 4.7).
The sequence number processing described in Section 6 MUST
successfully complete before any of the updates are processed.
o commConfirm contains either a terse community update confirmation
or a verbose community update confirmation. The terse response is
represented by TerseCommunityConfirm, and the verbose response is
represented by VerboseCommunityConfirm.
The TerseCommunityConfirm contains a single status code, indicating
the success or failure of the Community Update message processing.
If the community update failed, then the status code indicates the
reason for the failure. Each of the status codes is discussed in
Section 5.
The fields of VerboseCommunityConfirm are used as follows:
o status contains a single status code, indicating the success or
failure of the Community Update message processing. If the
community update failed, then the status code indicates the reason
for the failure. Each of the status codes is discussed in
Section 5.
o communities is OPTIONAL. When present, it contains the sequence
of community identifiers present in the trust anchor store after
the update is processed. When the trust anchor store belongs to
no communities, this field is omitted.
4.9. Sequence Number Adjust
The trust anchor store maintains the current sequence number for the
apex trust anchor and each management trust anchor authorized for
TAMP messages. Sequence number processing is discussed in Section 6.
The Sequence Number Adjust message can be used to provide the most
recently used sequence number to one or more targets, thereby
reducing the possibility of replay. The Sequence Number Adjust
message MUST be signed. For the Sequence Number Adjust message to be
valid, the trust anchor store MUST be an intended recipient of the
Sequence Number Adjust message, the sequence number MUST be equal to
or larger than the most recently stored sequence number for the
originating trust anchor, and the digital signature MUST be validated
by the apex trust anchor operational public key or an authorized
management trust anchor.
If the digital signature on the Sequence Number Adjust message is
valid, the sequence number is equal to or larger than the most
recently stored sequence number for the originating trust anchor, the
signer is authorized, and the trust anchor store is an intended
recipient of the TAMP message, then the trust anchor store MUST
update the sequence number associated with the originating trust
anchor and return a Sequence Number Adjust Confirm message. If a
Sequence Number Adjust Confirm message is not returned, then a TAMP
Error message SHOULD be returned.
The Sequence Number Adjust message contains an adjustment for the
sequence number of the TAMP message signer.
The Sequence Number Adjust content type has the following syntax:
tamp-sequence-number-adjust CONTENT-TYPE ::=
{ SequenceNumberAdjust IDENTIFIED BY id-ct-TAMP-seqNumAdjust }
id-ct-TAMP-seqNumAdjust OBJECT IDENTIFIER ::= { id-tamp 10 }
SequenceNumberAdjust ::= SEQUENCE {
Version [0] TAMPVersion DEFAULT v2,
msgRef TAMPMsgRef }
The fields of SequenceNumberAdjust are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o msgRef contains two items: the target and the seqNum. target
identifies the target(s) of the sequence number adjust message.
The TargetIdentifier syntax as described in Section 4.1 is used.
The allModules target is expected to be used for Sequence Number
Adjust messages. seqNum MUST be equal to or larger than the most
recently stored sequence number for this TAMP message signer, and
the value will be used to match the Sequence Number Adjust message
with the Sequence Number Adjust Confirm message. The sequence
number processing described in Section 6 applies, except that the
sequence number in a Sequence Number Adjust message is acceptable
if it matches the most recently stored sequence number for this
TAMP message signer. If sequence number checking completes
successfully, then the sequence number is adjusted; otherwise, it
remains unchanged.
4.10. Sequence Number Adjust Confirm
The Sequence Number Adjust Confirm message is a reply by a trust
anchor store to a valid Sequence Number Adjust message. The Sequence
Number Adjust Confirm message provides success or failure
information. Success is returned only if the sequence number for the
trust anchor that signed the Sequence Number Adjust message
originator is adjusted. If the sequence number cannot be adjusted,
then a failure is indicated, and the sequence number stored in the
trust anchor store is unchanged. The Sequence Number Adjust Confirm
message MAY be signed or unsigned. A Sequence Number Adjust Confirm
message MUST be signed if the trust anchor store is capable of
signing it.
The Sequence Number Adjust Confirm content type has the following
syntax:
tamp-sequence-number-adjust-confirm CONTENT-TYPE ::=
{ SequenceNumberAdjustConfirm IDENTIFIED BY
id-ct-TAMP-seqNumAdjustConfirm }
id-ct-TAMP-seqNumAdjustConfirm OBJECT IDENTIFIER ::=
{ id-tamp 11 }
SequenceNumberAdjustConfirm ::= SEQUENCE {
version [0] TAMPVersion DEFAULT v2,
adjust TAMPMsgRef,
status StatusCode }
The fields of SequenceNumberAdjustConfirm are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o adjust identifies the Sequence Number Adjust message to which the
trust anchor store is responding. The adjust structure repeats
the TAMPMsgRef from the Sequence Number Adjust message (see
Section 4.9). The sequence number processing described in
Section 6 MUST successfully complete to adjust the sequence number
associated with the Sequence Number Adjust message originator.
o status contains a single status code, indicating the success or
failure of the Sequence Number Adjust message processing. If the
adjustment failed, then the status code indicates the reason for
the failure. Each of the status codes is discussed in Section 5.
4.11. TAMP Error
The TAMP Error message is a reply by a trust anchor store to any
invalid TAMP message. The TAMP Error message provides an indication
of the reason for the error. The TAMP Error message MAY be signed or
unsigned. A TAMP Error message MUST be signed if the trust anchor
store is capable of signing it. For the request types defined in
this specification, TAMP Error messages MUST NOT be used to indicate
a request message was successfully processed. Each TAMP Error
message identifies the type of TAMP message that caused the error.
In cases where the TAMP message type cannot be determined, errors MAY
be returned via other means, such as at the protocol level, via an
attached display, etc.
The TAMP Error message content type has the following syntax:
tamp-error CONTENT-TYPE ::=
{ TAMPError IDENTIFIED BY id-ct-TAMP-error }
id-ct-TAMP-error OBJECT IDENTIFIER ::= { id-tamp 9 }
TAMPError ::= SEQUENCE {
version [0] TAMPVersion DEFAULT v2,
msgType OBJECT IDENTIFIER,
status StatusCode,
msgRef TAMPMsgRef OPTIONAL }
The fields of TAMPError are used as follows:
o version identifies version of TAMP. For this version of the
specification, the default value, v2, MUST be used.
o msgType indicates the content type of the TAMP message that caused
the error.
o status contains a status code that indicates the reason for the
error. Each of the status codes is discussed in Section 5.
o msgRef is OPTIONAL, but whenever possible it SHOULD be present.
It identifies the TAMP message that caused the error. It repeats
the target and seqNum from the TAMP message that caused the error
(see Sections 4.1, 4.3, 4.5, 4.7, and 4.9).
(page 45 continued on part 3)
