Security Event Token (SET)Oracle Corporationphil.hunt@yahoo.comGooglewdenniss@google.comCiscomorteza.ansari@cisco.comMicrosoftmbj@microsoft.comhttp://self-issued.info/
Security
Security Events Working GroupIdentitySecurityEventTokenInternet-DraftThis specification defines the Security Event Token, which may
be distributed via a protocol such as HTTP. The Security Event Token
(SET) specification profiles the JSON Web Token (JWT) and may be optionally signed
and/or encrypted. A SET describes a statement of fact that may be
shared by an event publisher with event subscribers.This specification defines an extensible Security Event Token
(SET) format which may be exchanged using protocols such as HTTP.
The specification builds on the JSON Web Token (JWT) format
in order to provide a self-contained token that can be optionally
signed using JSON Web Signature (JWS)
and/or encrypted using JSON Web Encryption (JWE) .For the purpose of this specification, an event is a statement
of fact by a publisher (also known as the event issuer) that the state of
a security subject (e.g., a web resource, token, IP address) it
controls or is aware of, has changed in some way (explicitly or
implicitly). A security subject may be permanent (e.g., a user account) or
temporary (e.g., an HTTP session) in nature. A state change
may include direct changes of entity state, implicit changes to state
or other higher-level security statements such as:
The creation, modification, removal of a resource.The resetting or suspension of an account.The revocation of a security token prior to its expiry.The logout of a user session. Or, A cumulative conclusion such as to indicate that a user has
taken over an email identifier that may have been used in the
past by another user.Based on some externally agreed criteria for an event feed,
the publisher distributes events to the appropriate subscribers of a
feed. While an event may be delivered via synchronous means (e.g.,
HTTP POST), the distribution of the event often happens
asynchronously to the change of state which generated the security
event. As an example, an OAuth2 Authorization Server
, having received a token revocation
request , may issue a token revocation
event to downstream web resource providers. Having been informed
of a token revocation, the OAuth2 web resource service provider
may add the token identifier to its local revocation list assuming
the token has not already expired.A subscriber having received an event, validates and interprets the
event and takes its own independent action, if any. For example,
having been informed of a personal identifier now being associated
with a different security subject (i.e., is being used by someone else), the
subscriber may choose to ensure that the new user is not granted
access to resources associated with the previous user. Or it may
not have any relationship with the subject, and no action is taken.While subscribers will often take actions upon receiving one
or more events, events MUST NOT be assumed to be commands or requests.
To do so requires complex bi-directional signals and error recovery
mechanisms that fall outside the scope of this specification.
The intent of this specification is to define a way of exchanging
statements of fact that subscribers may interpret for their own
purposes. Since events are typically historical statements by a publisher
and are not commands, idempotency or lack thereof, does not apply.Unless otherwise specified, this specification uses example
events intended to serve as non-normative examples showing how an
event may be constructed. It is expected that other "profiling"
specifications will use this specification to define normative
events within some specified context or protocol.This specification is scoped to security and identity related events.
While security event tokens may be used for other purposes, the specification
only considers security and privacy concerns relevant to identity
and personal information.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in . These keywords are capitalized when used to
unambiguously specify requirements of the protocol or application
features and behavior that affect the inter-operability and security of
implementations. When these words are not capitalized, they are meant
in their natural-language sense.For purposes of readability, examples are not URL encoded.
Implementers MUST percent encode URLs as described in Section 2.1 of.Throughout this document, all figures MAY contain spaces and extra
line-wrapping for readability and space limitations. Similarly, some
URIs contained within examples have been shortened for space and
readability reasons.
The following definitions are used with SETs:
The Feed Publisher creates
SETs to be distributed to registered subscribers. In JWT
terminology, the Feed Publisher is also known as the issuer
(iss).
An SET is a
JWT that is to be
distributed to one or more registered subscribers. A SET MAY
be signed or encrypted using JWS and/or JWE for authentication
and confidentiality reasons.
A Feed is a logical
grouping of SETs or a context under which SETs may be issued.
A Subscriber registers with the Feed Publisher to subscribe
to SETs associated with a Feed. How a Feed is defined or
the method for subscription is out-of-scope of this specification.
A Subscriber
registers to receive SETs from a Feed Publisher using a protocol
such as HTTP. The method of registration and delivery is out-of-scope
of this specification.
A
Security Subject is the entity to which a SET refers. A
Security Subject may be a principle (e.g.,
Section 4.1.2), a web resource,
or other thing such as an IP address that a SET might reference.A SET conveys a statement (in the form of a JWT
) about a single security event in relation
to a Security Subject that may be of
interest to a Subscriber or set of Subscribers receiving SETs from
a Feed Publisher.The schema and structure of a SET follows the JWT
specification. A SET has the following structure:
An outer JSON structure that acts as the SET envelope. The envelope
contains a set of name/value pairs called the JWT Claims Set,
typically common to every SET or common to a number of different
Security Events within a single profiling specification or a
related series of specifications. Claims in the envelope SHOULD
be registered in the JWT Token Claims Registry Section 10.1 or be
Public Claims or Private Claims as also defined in .Envelope claims that are profiled and defined
in this specification are used to validate a SET and declare
the event data included in the SET. The claim events
identifies the security event types being expressed related to the
Security Subject and MAY also include event-specific data.Each JSON member of the events object is a
name/value pair. The JSON attribute name is a URI String value
that expresses an event type. The corresponding value is a JSON object known as the
event "payload". The payload JSON object contains claims
typically unique to the event's URI type value and are not
registered as JWT claims. These claims are defined
by their associated event specification. An event with no
payload claims SHALL be represented as the empty JSON object
({}). In many cases, one event URI expresses
the primary event URI, while other events might be considered extensions
that MAY be used to do things such as:A categorization event type to provide classification
information (e.g., threat type or level).An enhancement of an existing specifications the arise over time.An extensions needed to link a potential series of events.Localized specific purpose extensions needed between a
particular publisher and subscriber.The following is a non-normative example showing the JWT Claims Set for a hypothetical
SCIM password reset SET. This example shows an extension
(https://example.com/scim/event/passwordResetExt)
that is used to convey additional information -- in this case, the current
count of reset attempts:
{
"jti": "3d0c3cf797584bd193bd0fb1bd4e7d30",
"iat": 1458496025,
"iss": "https://scim.example.com",
"aud": [
"https://jhub.example.com/Feeds/98d52461fa5bbc879593b7754",
"https://jhub.example.com/Feeds/5d7604516b1d08641d7676ee7"
],
"sub": "https://scim.example.com/Users/44f6142df96bd6ab61e7521d9",
"events": {
"urn:ietf:params:scim:event:passwordReset":
{ "id":"44f6142df96bd6ab61e7521d9"},
"https://example.com/scim/event/passwordResetExt":
{ "resetAttempts":5}
}
}
The event in the figure above expresses hypothetical password
reset event for SCIM . The JWT consists of:An events claim specifying the hypothetical
SCIM URN (urn:ietf:params:scim:event:passwordReset)
for a password reset, and a custom extension,
https://example.com/scim/event/passwordResetExt,
that is used to provide additional event information such as the
current count of resets.An iss
claim, denoting the event publisher.The sub claim specifies the SCIM
resource URI that was affected.The aud claim specifies the
intended audiences for the event. In practical terms, an audience MAY be
the URI for an event feed that a client has subscribed to.
In this example, the SCIM event
indicates that a password has been updated and the current
password reset count is 5. Notice that the value for
"resetAttempts" is actually part of its own JSON object associated
with its own event URI attribute.
Here is another example JWT Claims Set for a security event token, this one
for a Logout Token:
{
"iss": "https://server.example.com",
"sub": "248289761001",
"aud": "s6BhdRkqt3",
"iat": 1471566154,
"jti": "bWJq",
"sid": "08a5019c-17e1-4977-8f42-65a12843ea02",
"events": {
"http://schemas.openid.net/event/backchannel-logout": {}
}
}
Note that the above SET has an empty JSON object and
uses the JWT registered claims sub
and sid to identify the subject
that was logged-out.In the following example JWT Claims Set, a fictional medical service collects
consent for medical actions and notifies other parties. The individual
for whom consent is identified was originally authenticated via
OpenID Connect. In this case, the issuer of the security event is an
application rather than the OpenID provider:
{
"jti": "fb4e75b5411e4e19b6c0fe87950f7749",
"sub": "248289761001",
"iat": 1458496025,
"iss": "https://my.examplemed.com",
"aud": [
"https://rp.example.com"
],
"events": {
"https://openid.net/heart/specs/consent.html":{
"iss":"https://connect.example.com",
"consentUri":[
"https://terms.examplemed.com/labdisclosure.html#Agree"
]
}
}
}
In the above example, the attribute iss contained within the
payload for the event https://openid.net/heart/specs/consent.html, refers
to the issuer of the Security Subject (sub) rather than the event
issuer https://my.examplemed.com. They are
distinct from the top level value of iss
which always refers to the issuer of the event - a medical consent
service that is a relying party to the OpenID Provider.
The following are claims that are based on
claim definitions and are profiled for use in an event
token:As defined by
Section 4.1.7 contains a unique
identifier for an event. The identifier SHOULD be unique within
a particular event feed and MAY be used by clients to track
whether a particular event has already been received. This
claim is REQUIRED.A single valued
String containing the URI of the service provider publishing
the SET (the issuer). This claim is REQUIRED. Note that when
a SET is expressing an event about a Security Subject for
which the SET issuer is not the issuer of the Security Subject,
the conflict SHALL be resolved by including the Security Subject
iss value within the event "payload"
(see events claim). As defined in Section 4.1.3,
an array containing the StringOrURI values representing the
audience of the event. Values are typically URLs of
the feeds the event is associated with. This claim is RECOMMENDED.As defined by Section 4.1.6,
a value containing a NumericDate, which represents when the
event was issued. Unless otherwise specified,
the value SHOULD be interpreted by the subscriber as equivalent
to the actual time of the event. This claim is REQUIRED.
Defined by
Section 4.1.5, a number
whose value is a NumericDate. In the context of the SET token
it SHALL be interpreted to mean a date in which
the event is believed to have occurred (in the past) or will occur in the
future. Note: there MAY be some cases where "nbf"
is still smaller than "iat" such as when it took an extended
time for a SET to be issued (for example after some analysis).
This claim is OPTIONAL.As defined by Section 4.1.2,
a String or URI value representing the principal or the subject of the SET.
This is usually the entity whose "state" was changed. For example,
an IP Address was added to a black list. A URI representing a
user resource that was modified. A token identifier for a revoked
token. If used, the profile specification SHOULD
define the content and format semantics for the value. This claim
is OPTIONAL, as the principal for any given profile may already be
identified without the inclusion of a subject claim.As defined by , this claim
is time on which the JWT MUST NOT be accepted for processing. In
the context of a SET however, this notion does not apply since
a SET reflects something that has already been processed and is
historical in nature. While some specifications MAY have a need
for this claim, its use in general cases is NOT RECOMMENDED.The following are new claims defined by this specification:
The semantics of this claim is to define a set of event statements
that each MAY add additional claims to fully describe a single
logical event that has occurred (e.g. a state change to a subject).
Multiple event statements of the same type SHALL NOT be accepted.
The events
claim SHOULD NOT be used to express multiple logical events.The value of events is a
JSON object whose members are a set of JSON name/value pairs
whose names are URIs representing the event statements being
expressed. Event URI values SHOULD be stable values (e.g. a
permanent URL for an event specification). For each name present,
the corresponding value
SHALL be a JSON object. The JSON object MAY be an empty
object ({}), or it MAY be a JSON
object containing data as described by the profiling event
specification.
An OPTIONAL String value that represents a unique transaction
identifier. In cases where multiple SETs are issued based on
different event URIs, the transaction
identifier MAY be used to correlate SETs to the same
originating event or stateful change.A SET is a JWT that is
constructed by building a JSON structure that constitutes an event
object and which is then used as the body of a JWT.While this specification uses JWT to convey a SET, implementers
SHALL NOT use SETs to convey authentication or authorization assertions.The
following is an example JWT Claims Set for a security event token (which has been formatted
for readability):
{
"jti": "4d3559ec67504aaba65d40b0363faad8",
"iat": 1458496404,
"iss": "https://scim.example.com",
"aud": [
"https://scim.example.com/Feeds/98d52461fa5bbc879593b7754",
"https://scim.example.com/Feeds/5d7604516b1d08641d7676ee7"
],
"events": {
"urn:ietf:params:scim:event:create": {
"ref":
"https://scim.example.com/Users/44f6142df96bd6ab61e7521d9",
"attributes":["id", "name", "userName", "password", "emails"]
}
}
}
When transmitted, the above JSON body must be converted into a JWT
as per .The following is an example of a SCIM Event expressed as
an unsecured JWT. The JWT header of:{"alg":"none"}Base64url encoding of the octets of the UTF-8
representation of the header yields:eyJhbGciOiJub25lIn0The example JSON Event Data is encoded as
follows:
e3sgIAogICJqdGkiOiAiNGQzNTU5ZWM2NzUwNGFhYmE2NWQ0MGIwMzYzZmFhZDgiLAog
ICJpYXQiOiAxNDU4NDk2NDA0LAogICJpc3MiOiAiaHR0cHM6Ly9zY2ltLmV4YW1wbGUu
Y29tIiwgIAogICJhdWQiOiBbCiAgICJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vRmVl
ZHMvOThkNTI0NjFmYTViYmM4Nzk1OTNiNzc1NCIsCiAgICJodHRwczovL3NjaW0uZXhh
bXBsZS5jb20vRmVlZHMvNWQ3NjA0NTE2YjFkMDg2NDFkNzY3NmVlNyIKICBdLCAgCiAg
CiAgImV2ZW50cyI6IHsKICAgICJ1cm46aWV0ZjpwYXJhbXM6c2NpbTpldmVudDpjcmVh
dGUiOiB7CiAgICAgICJyZWYiOgogICAgICAgICJodHRwczovL3NjaW0uZXhhbXBsZS5j
b20vVXNlcnMvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsCiAgICAgICJhdHRyaWJ1
dGVzIjpbImlkIiwgIm5hbWUiLCAidXNlck5hbWUiLCAicGFzc3dvcmQiLCAiZW1haWxz
Il0KICAgIH0KICB9Cn0The encoded JWS signature is the empty string.
Concatenating the parts yields:
eyJhbGciOiJub25lIn0
.
e3sgIAogICJqdGkiOiAiNGQzNTU5ZWM2NzUwNGFhYmE2NWQ0MGIwMzYzZmFhZDgiLAog
ICJpYXQiOiAxNDU4NDk2NDA0LAogICJpc3MiOiAiaHR0cHM6Ly9zY2ltLmV4YW1wbGUu
Y29tIiwgIAogICJhdWQiOiBbCiAgICJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vRmVl
ZHMvOThkNTI0NjFmYTViYmM4Nzk1OTNiNzc1NCIsCiAgICJodHRwczovL3NjaW0uZXhh
bXBsZS5jb20vRmVlZHMvNWQ3NjA0NTE2YjFkMDg2NDFkNzY3NmVlNyIKICBdLCAgCiAg
CiAgImV2ZW50cyI6IHsKICAgICJ1cm46aWV0ZjpwYXJhbXM6c2NpbTpldmVudDpjcmVh
dGUiOiB7CiAgICAgICJyZWYiOgogICAgICAgICJodHRwczovL3NjaW0uZXhhbXBsZS5j
b20vVXNlcnMvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsCiAgICAgICJhdHRyaWJ1
dGVzIjpbImlkIiwgIm5hbWUiLCAidXNlck5hbWUiLCAicGFzc3dvcmQiLCAiZW1haWxz
Il0KICAgIH0KICB9Cn0
.
For the purpose of a simpler example in
an unencrypted token was shown. When SETs are not signed or
encrypted, the subscriber MUST depend upon TLS and HTTP to
authenticate the sender and the security of the channel to
authenticate the SET and its sender.
When validation (i.e. auditing), or additional transmission
security is required, JWS Signing and JWS Encryption MAY be used.
To create and or validate a signed or encrypted SET, follow
the instructions in section 7 of .SETs may often contain sensitive information. Therefore,
methods for distribution of events SHOULD require the use of a
transport-layer security mechanism when distributing events.
Parties MUST support TLS 1.2 and MAY support
additional transport-layer mechanisms meeting its security
requirements. When using TLS, the client MUST perform a TLS/SSL server
certificate check, per . Implementation
security considerations for TLS can be found in "Recommendations for
Secure Use of TLS and DTLS" .Security Events distributed through third-parties or that carry personally
identifiable information, SHOULD be encrypted using JWE
or secured for confidentiality by other means.
Security Events distributed without authentication over the channel, such
as via TLS ( and ),
and/or OAuth2 , or Basic Authentication ,
MUST be signed using JWS so
that individual events MAY be authenticated and validated by the subscriber.This specification does not define a delivery mechanism by itself.
In addition to confidentiality and integrity (discussed above), implementers
and profile specifications MUST consider the consequences of delivery
mechanisms that are not secure and/or not assured. For example, while
a SET may be end-to-end secured using JWE encrypted SETs, without TLS
there is no assurance that the correct endpoint received the SET and
that it could be successfully processed.As defined in this specification, there is no defined way to order
multiple SETs in a sequence. Depending on the type and nature of SET
event, order may or may not matter. For example, in provisioning,
event order is critical -- an object could not be modified before it
was created. In other SET types, such as a token revocation, the order
of SETs for revoked tokens does not matter. If however, the event was
described as a log-in or logged-out status for a user subject, then
order becomes important.Extension specifications and implementers SHOULD take caution when
using timestamps such as iat to define order. Distributed systems will have
some amount of clock-skew and thus time by itself will not guarantee order.Specifications profiling SET SHOULD define a mechanism for detecting
order or sequence of events. For example, the txn
claim could contain an ordered value (e.g., a counter) that the publisher defines.When SETs are delivered asynchronously and/or out-of-band with respect to
the original action that incurred the security event, it is important
to consider that a SET might be delivered to a Subscriber in advance
or well behind the process that caused the event. For example, a
user having been required to logout and then log back in again, may
cause a logout SET to be issued that may arrive at the same time
as the user-agent accesses a web site having just logged-in. If
timing is not handled properly, the effect would be to erroneously
treat the new user session as logged out. Profiling specifications
SHOULD be careful to anticipate timing and subject selection information.
For example, it might be more appropriate to cancel a "session"
rather than a "user". Alternatively, the specification could use timestamps
that allows new sessions to be started immediately after a stated
logout event time.Because states that all claims that are not understood
by implementations MUST be ignored., there is a consideration that
a SET token might be confused as an access or authorization token in
the case where a SET is mistakenly or intentionally intercepted and
presented as an access token. To avoid this, it is recommended that
implementers consider one or more of the following:Avoid use of the JWT claim exp within the
envelope.Where possible, use a separate aud
claim value to distinguish between the SET subscriber and the
audience of an access token. For example, a Logout while intended
for the same relying party could use a different audience to
distinguish between normal access and logout notification.Modify access validation systems to check for the presence of
the events claim as a means to detect
security event tokens. This is particularly useful if the same endpoint
may receive both types of tokens.Consider avoiding use of the sub
claim at the top level.If a SET needs to be retained for audit purposes, JWS MAY
be used to provide verification of its authenticity.Event Publishers SHOULD attempt to specialize feeds so that the content
is targeted to the specific business and protocol needs of subscribers.When sharing personally identifiable information or information
that is otherwise considered confidential to affected users, the
publishers and subscribers MUST have the appropriate legal agreements
and user consent in place.The propagation of subject identifiers can be perceived as personally
identifiable information. Where possible, publishers and subscribers
should devise approaches that prevent propagation -- for example, the
passing of a hash value that requires the subscriber to already know
the subject.
This specification registers the events and
txn claims in the IANA
"JSON Web Token Claims" registry
established by .
Claim Name: events
Claim Description: Security Event Object
Change Controller: IESG
Specification Document(s): of [[ this specification ]]
Claim Name: txn
Claim Description: Transaction Identifier
Change Controller: IESG
Specification Document(s): of [[ this specification ]]
JSON Web Token ClaimsIANAThe editors would like to thank the participants in the IETF id-event
mailing list and related working groups for their support of this specification.Draft 01 - PH - Renamed eventUris to eventsDraft 00 - PH - First DraftDraft 01 - PH - Fixed some alignment issues with JWT. Remove event type attribute.Draft 02 - PH - Renamed to Security Events, removed questions, clarified examples and intro text, and added security and privacy section.Draft 03 - PH General edit corrections from Sarah SquireChanged "event" term to "SET"Corrected author organization for William Denniss to GoogleChanged definition of SET to be 2 parts, an envelope and 1 or more payloads.Clarified that the intent is to express a single event with optional extensions only.
- mbj - Registered events claim, and proof-reading corrections.Draft 04 - PH - Re-added the "sub" claim with clarifications that any SET type may use it.Added additional clarification on the use of envelope vs. payload attributesAdded security consideration for event timing.Switched use of "attribute" to "claim" for consistency.Revised examples to put "sub" claim back in the top level.Added clarification that SETs typically do not use "exp".Added security consideration for distinguishing Access Tokens and SETs.Draft 05 - PH - Fixed find/replace error that resulted in claim being spelled claimcDraft 06 - PH - Corrected typosNew txn claimNew security considerations Sequencing and Timing Issues
Draft 07 -
PH - Moved payload objects to be values of event URI attributes, per discussion.mbj - Applied terminology consistency and grammar cleanups.Draft 08 - PH - Added clarification to status of examplesChanged from primary vs. extension to state that multiple
events may be expressed, some of which may or may not
be considered extensions of others (which is for the subscriber
or profiling specifications to determine).Other editorial changes suggested by Yaron