omg dds security. 4th revised submission

Your systems. Working as one.

DDS SECURITY 4rd Revised Submission (Joint) mars/2013-‐03-‐10

Doc num: mars/2013-‐03-‐10 SpecificaKon lead: Gerardo Pardo-‐Castellote, Ph.D. CTO, Real-‐Time InnovaKons, Inc.

SubmiRers: Real-‐Time InnovaKons, Inc. PrismTech Corp. eProsima (supporter)

© 2012 Real-‐Time InnovaKons, Inc. -‐ All rights reserved

Agenda

•  Status recap •  Summary of submission

• What has changed?

•  Some details

•  Status & Conclusion

3/21/13 © 2012 Real-‐Time InnovaKons, Inc. -‐ All rights reserved 2

Status recap

•  Started with two separate submissions by RTI and PrismTech – RTI submission focused on the mandatory requirements for an SPI Architecture and built-‐in SPIs

– PrismTech discussed on the use of technologies such as (MIKEY / SRTP) to support the needs of secure DDS

•  As of the December 2012 meeKng PrismTech joined the RTI submission


Agenda



•  How the submission allows a specializaKon to use MIKEY and SRTP



Intro to DDS Security and scope of this specificaKon


Security as a system problem

•  UlKmately security is a system property –  Involves hardware, so`ware, humans, procedures…

•  Most directly related:

1.  Securing the data-‐centric bus

2.  IntegraKng across security domains

3.  Securing the operaKng system

4.  Securing the hardware & so`ware configuraKon


Scope of the RFP

Out of Scope

Scope of the DDS Security RFP

Three security boundaries

•  Boundary security

•  Transport-‐Level – Network (layer 3) security – Session (layer 4/5) security

•  Fine-‐grained Data-‐Centric Security

3/21/13 © 2012 Real-‐Time InnovaKons, Inc. -‐ All rights reserved

Ul:mately you need to implement the 3 of them

7

Fine-‐Grained Data-‐Centric Security

•  Access control per Topic •  Read versus-‐write permissions

•  Field-‐specific permissions

Topics

3/21/13 8 © 2012 Real-‐Time InnovaKons, Inc. -‐ All rights reserved

Threats 1.  Unauthorized subscripKon 2.  Unauthorized publicaKon 3.  Tampering and replay 4.  Unauthorized access to data

by infrastructure services


Alice: Allowed to publish topic T Bob: Allowed to subscribe to topic T Eve: Non-‐authorized eavesdropper Trudy: Intruder Trent: Trusted infrastructure service Mallory: Malicious insider

Data-‐centric/mulKcast Insider Threats

•  Two insider threats affecKng (mulKcast) data-‐centric systems are of unique significance 1.   Reader mis-‐behaves as unauthorized writer

An applicaKon uses knowledge gained as authorized reader to spoof the system as a writer

2.   Compromise of Infrastructure Service A service that is trusted to read and write data on behalf

of others (e.g. a persistence service ) becomes compromised


Reader mis-‐behaves as unauthorized writer

•  SituaKon: –  Alice -‐ creates a Crypto Key per Topic/DataWriter –  Alice -‐ shares its Key with all intended readers as needed to mulKcast –  Mallory – is an authorized reader so it has Alice’s key –  Mallory – behaves maliciously and uses Alice’s key to create fake UDP messages pumng

Alice’s informaKon (IP, Port, GUIDs, etc.) but with bad data.

•  ImplicaKons: –  Bob sees message from Mallory and processes it believing it is from Alice –  Mallory can provide a system-‐wide failure for all subscribers to topic T, making them process

wrong data, delete instances, –  Depending on the Topic this can be catastrophic for the system

•  Notes: –  The problem is that all secrets shared by Alice and Bob are also known to Mallory

•  So the aRack cannot be solved with a MAC or HMAC if Alice’s key is also shared with all readers… –  The problem can be solved with a digital signature but that is 1000X slower than a MAC


Summary of RFP requirements


RFP Mandatory Requirements

Proposals shall define … 6.5.1 … a Plaoorm Independent Security Model for DDS

independent of the programming language used… 6.5.2 … a collecKon of Plaoorm Independent IntercepKon

Points and SPIs … 6.5.3 … built-‐in Plaoorm Independent Security Plugins that

implement the Plaoorm Independent Interfaces 6.5.4 … plaoorm specific mappings for the built-‐in plugins to

all the language PSMs supported by DDS 6.5.5 … how the DDS Interoperability Wire Protocol is used

to allow DDS applicaKons to interoperate securely


Mandatory Requirements 6.5.1: Security Model

The Security Model for DDS shall … 6.5.1.1 … support mechanisms that establish the ability for a DDS ParKcipant to run in a

plaoorm

6.5.1.2 … support mechanisms to configure and access the credenKals of the underlying DDS ParKcipants …

6.5.1.3 … allow specificaKon of authorizaKon policies, controlling

[1] Joining a DDS Domain

[2] Access to DDS Discovery Data [3] Publishing a DDS Topic, [4] Subscribing to a DDS Topic

[5] Publishing on a DDS ParKKon, [6] Subscribing on a DDS ParKKon

6.5.1.4 … include the concept of data tagging

6.5.1.5 … support mechanism for ensuring data integrity, including

[1] traceability, pedigree, and tamper [2] digital signatures

[3] data encrypKon

[4] use of different keys for data from different DataWriters


Mandatory Requirements 6.5.2: Set of IntercepKon Points and SPIs

The Plugin SPIs shall … 6.5.2.1 … allow applicaKons to exchange credenKals with a DDS ParKcipant

[1] exchanging credenKals for authenKcaKon

[2] delegaKon of authority for authenKcaKon

6.5.2.2 … allow an external plugin to perform all the authorizaKon funcKons

[1] full support of the authorizaKon policies [3] support delegaKon of authority

[4] support delegaKon of authority separately for each DDS Topic

6.5.2.3 … allow an external plugin to perform all the tagging and tag-‐accessing funcKons

6.5.2.4 … allow an external plugin to perform all the encrypKon and decrypKon funcKons

6.5.2.5 … external plugin to perform all the digital signing and verificaKon funcKons


RFP OpKonal Requirements

Proposals may define authorizaKon policies that control … 6.6.1 … the content a DDS ParKcipant is allowed to publish on a Topic. 6.6.2 … the content a DDS ParKcipant is allowed to subscribe on a Topic.. 6.6.3 … the QoS Policies a DDS ParKcipants can use when publishing a Topic 6.6.4 … the QoS Policies a DDS ParKcipant can use when subscribing to a

Topic.

Proposals may define … 6.6.5 … data-‐tagging plugins that apply different tags for each data-‐sample

published by a DDS DataWriter. 6.6.6 … built-‐in plugins that interoperate with standard authenKcaKon and

authorizaKon protocols and services, such as, LDAP and SAML. 6.6.7 … a PSM mapping of the DDS-‐RTPS Interoperability Wire Protocol to a

secure transport, such as, DTLS. 6.6.8 … a PSM of the DDS-‐RTPS Interoperability Wire Protocol allowing

interoperability over UnidirecKonal Transports.


Summary of DDS Security spec.


Submission Guiding Principles •  Performance & Scalability

–  Do not impact parts of the system that do not have security needs

–  Allow opKng out of specific features such as MAC, EncrypKon. Digital Signature with sufficient granularity

–  Limit use of asymmetric keys to discovery & session establishment

–  Support MulKcast

•  Robustness & Availability –  Be robust to the failure or compromise of any single component.

–  Limit privileges of infrastructure services and relays

–  Avoid centralized policy decisions/services

–  Avoid mulK-‐party key agreement protocols

•  Fitness to data-‐centric model –  Express policies and permissions in terms of familiar DDS terminology and objects –  Support all of DDS: consumpKon of samples out of order, best efforts, Kme filters, history cache,

etc.

•  Leverage exis:ng technologies –  Support plugging in exiKng technologies for ciphers, MAC, PKI

•  Ease of use & Flexibility –  DO not preclude integraKng with their exisKng security and crypto infrastructure.


Audience and Purpose for this SpecificaKon

•  Audience: – DDS vendors/implementers, not the users of DDS

•  Purpose: – Define a Security Model for DDS systems – Define concrete IntercepKon points in the middleware where SPI interfaces must be called

– Define concrete SPI Interfaces vendors must invoke at the IntercepKon Points and the behavior upon various returns

– Define specific SPI implementaKons to the extent required for interoperability

– NOT guidance to users implemenKng secure DDS systems – NOT definiKon of security technologies beyond what is required to implement the specificaKon


DDS Security covers 4 related concerns


Security Plugin APIs & Behavior

DDS & RTPS support for Security

Buil:n Plugins

Security Model

Security Model


Security Model

•  A security model is defined in terms of: – The subjects (principals) – The objects being protected

•  The operaKons that are protected on the objects – Access Control Model

•  A way to map each subject to the objects they can perform operaKons on and which are the allowed operaKons


MR# 6.5.1

Security Model Example: UNIX FileSystem (simplified)

•  Subjects: Users, specifically processes execuKng on behalf of a specific userid •  Protected Objects: Files and Directories

•  Protected OperaKons on Objects:

–  Directory.list, Directory.createFile, Directory.createDir, Directory.removeFile, Directory.removeDir, Directory.renameFile

–  File.view, File.modify, File.execute

•  Access Control Model: –  A subject is given a userId and a set of groupId –  Each object is assigned a OWNER and a GROUP

–  Each Object is given a combinaKon of READ, WRITE, EXECUTE permissions for the assigned OWNER and GROUP

–  Each protected operaKon is mapped to a check, for example •  File.view is allowed if and only if

–  File.owner == Subject.userId AND File.permissions(OWNER) includes READ

–  OR File.group IS-‐IN Subject.groupId[] AND File.permissions(GROUP) includes READ


DDS Security Model •  Subjects: DDS DomainParKcipant (ParKcipant GUID) •  Protected Objects: DDS Domain and DDS Topic

•  Protected Opera:ons on Objects (logical view):

–  DomainParKcipant.join –  DomainParKcipant.add_read_parKKon

–  DomainParKcipant.add_write_parKKon

–  Topic.create –  Topic.set_qos –  Topic.set_reader_qos –  Topic.read –  Topic.set_writer_qos –  Topic.write –  Topic.create_instance –  Topic.update_instance –  Topic.dispose_instance


MR# 6.5.1

Mapping of DDS API to protected operaKons


DDS API Call Protected Opera:on DomainParKcipantFactory.create_parKcipant Discovery.match_remote_parKcipant DomainParKcipant.join DomainParKcipant.create_publisher Publisher.set_qos DomainParKcipant.add_write_parKKon DomainParKcipant.create_subscriber Subscriber.set_qos DomainParKcipant.add_read_parKKon

DomainParKcipant.create_topic Discovery.dicover_topic Topic.create, Topic.seq_qos Topic.set_qos Topic.set_qos Subscriber.create_datareader Discovery.dicover_datareader Topic.read, Topic.set_reader_qos DataReader.set_qos Discovery.change_datareader_qos Topic.set_reader_qos Publisher.create_datawriter Discovery.dicover_datawriter Topic.write, Topic.set_writer_qos DataWriter.set_qos Discovery.change_datawriter_qos Topic.set_writer_qos DataWriter.register_instance DataWriter.write Protocol.receive_instance_new

Topic.create_instance

DataWriter.dispose Protocol.receive_dispose Topic.dispose_instance

MR# 6.5.1

DDS & RTPS Support for Security


Support for Security in DDS & RTPS

•  DDS ParKcipants need to exchange security informaKon –  CerKficates for AuthenKcaKon & Permissions –  Handshake messages for mutual authenKcaKon and shared-‐secret establishment

–  KeyTokens for key-‐exchange •  These messages reuse exisKng DDS mechanisms

–  Discovery topics –  BuilKn data readers / writers

•  EncrypKon and signatures introduce new RTPS Submessage and Submessage elements –  SecureSubMessage –  SecuredData


Security informaKon propagated via DDS discovery

2 addiKonal aRributes added to ParKcipantBuilKnTopicData:

IdenKtyToken idenKty;

PermissionsToken permissions;


struct Property { string<> name; string<> value; }; typedef sequence<Property> PropertySeq;

struct Token { string<> token_classid; string<> wrapper_classid; PropertySeq properKes; sequence<octet> value; sequence<octet> wrapped_value; };

typedef Token Iden:tyToken; typedef Token PermissionsToken;

Security informaKon exchanged via BuilKnParKcipantMessageWriter

4 addiKonal kinds:

KIND_SECURITY_AUTH_HANDSHAKE

KIND_SECURITY_PARTICIPANT_CRYPTO_TOKENS

KIND_SECURITY_DATAWRITER_CRYPTO_TOKENS KIND_SECURITY_DATAREADER_CRYPTO_TOKENS


struct CryptoTokensMsg { octet sending_guid[16]; octet receiving_guid[16]; CryptoTokenSeq crypto_tokens; };

typedef Token CryptoToken; sequence<CryptoToken> CryptoTokenSeq;

typedef Token HandshakeTokenMsg; typedef CryptoTokensMsg Par:cipantCryptoTokensMsg; typedef CryptoTokensMsg DatawriterCryptoTokensMsg; typedef CryptoTokensMsg DatareaderCryptoTokensMsg;

BuilKnParKcipantMessageWriter


typedef octet GuidPrefix_t[12]; typedef octet Par:cipantMessageDataKind[4];

struct Par:cipantMessageData { GuidPrefix_t par:cipantGuidPrefix; //@Key Par:cipantMessageDataKind kind; //@Key sequence<octet> data; };

Background: RTPS


RTPS SubMessage

RTPS Header

RTPS SubMessage

RTPS SubMessage

RTPS SubMessage

SubMsg Header

SubMsg Element

SubMsg Element

SerializedData

RTPS SubMessage

RTPS Message

Cryptographic SPI at the wire-‐protocol level

© 2012 RTI • UNCLASSIFIED • PROPRIETARY

RTPS SubMessage

SerializedData

RTPS SubMessage

SerializedData

RTPS Header RTPS Header

RTPS SubMessage (*)

RTPS SubMessage

SecuredData

SerializedData

RTPS SubMessage

SecuredData

SerializedData

RTPS SubMessage (*)

RTPS SubMessage (*)

Secure encoding

Secure decoding

Message TransformaKon

RTPS SubMessage

SerializedData


RTPS SubMessage

SecuredData

SerializedData

encode_serialized_data

RTPS SubMessage

RTPS SubMessage

RTPS SubMessage

RTPS Header

encode_datawriter_submessage

RTPS Header

RTPS SecureSubMsg

RTPS SubMessage

RTPS SubMessage

RTPS SubMessage

RTPS SubMessage

RTPS Header

encode_datareader_submessage

RTPS Header

RTPS SecureSubMsg

RTPS SubMessage

RTPS SubMessage

RTPS SubMessage

RTPS SubMessage

RTPS SubMessage


RTPS SecureSubMsg

encode_rtps_message

RTPS SubMessage RTPS SubMessage

RTPS SubMessage

RTPS SubMessage

RTPS SubMessage

SerializedData

RTPS SubMessage

SerializedData


RTPS SecSubMsg

RTPS SubMessage

SecuredData

SerializedData

RTPS SubMessage

SecuredData

SerializedData

RTPS SecSubMsg

RTPS SecSubMsg

encode_rtps_message

encode_datawriter_submessage

encode_serialized_data

Security Plugins


Plaoorm Independent IntercepKon Pts + SPIs


Service Plugin Purpose Interactions

Authentication Authenticate the principal that is joining a DDS Domain.

Handshake and establish shared secret between participants

The principal may be an application/process or the user associated with that application or process. Participants may messages to do mutual authentication and establish shared secret

Access Control Decide whether a principal is allowed to perform a protected operation.

Protected operations include joining a specific DDS domain, creating a Topic, reading a Topic, writing a Topic, etc.

Cryptography Perform the encryption and decryption operations. Create & Exchange Keys. Compute digests, compute and verify Message Authentication Codes. Sign and verify signatures of messages.

Invoked by DDS middleware to encrypt data compute and verify MAC, compute & verify Digital Signatures

Logging Log all security relevant events Invoked by middleware to log

Data Tagging Add a data tag for each data sample

MR# 6.5.2

Plaoorm Independent SPIs


MR# 6.5.2

BuilKn Plugins


SPI Buil:n Plungin Notes

AuthenKcaKon DDS:Auth:PKI-‐RSA/DSA-‐DH Uses PKI with a pre-‐configured shared CerKficate Authority. DSA and Diffie-‐Hellman for authenKcaKon and key exchange Establishes shared secret

AccessControl DDS:Access:PKI-‐Signed-‐XML-‐Permissions

Permissions document signed by shared CerKficate Authority

Cryptography DDS:Crypto:AES-‐CTR-‐HMAC-‐RSA/DSA-‐DH

Protected key distribuKon AES128 and AES256 for encrypKon (in counter mode) SHA1 and SHA256 for digest HMAC-‐SHA1 and HMAC-‐256 for MAC

DataTagging Discovered_EndpointTags Send Tags via Endpoint Discovery

Logging DedicatedDDS_LogTopic

MR# 6.5.3

Mapping to DDS Language PSMs

•  Plugin SPIs to be defined using IDL •  IDL-‐to-‐Language mappings used for each Language PSM

•  No need to define mappings to new Javs5 PSM and STD-‐C++ PSM –  IDL-‐derived Language PSMs suffice as these are low-‐level interfaces that will only be exercised by SPI plugin implementers.

NOTE: IDL file is missing from submission


MR# 6.5.4

Use of DDS Interoperability Protocol

•  Uses: Buil%nPar%cipantMessageWriter/Reader – Msg kind: KIND_SECURITY_AUTH_HANDSHAKE

•  data: MessageToken

– Msg kind: KIND_SECURITY_KEY_TOKEN •  Data: KeyToken

•  Discovery propagates addiKonal security info – Buil:nPar:cipantTopicData

•  Iden:tyToken [PID_SEC_IDENTITY_TOKEN] •  PermissionsToken [PID_SEC_PERMISSIONS_TOKEN]

– Buil:nPublica:onTopicData •  DataTags [PID_SEC_DATA_TAGS]


MR# 6.5.5

Agenda



•  Some details



What has changed •  Unified Token representaKons

–  All Tokens use common data-‐type –  Tokens can be encrypted (wrapped) by key

•  AuthenKcaKon SPI can now do: –  Configurable mulK-‐step Handshake (subsumes Challenge) –  Establishment of Shared Secret

•  Cryptography SPI –  Focuses just on Crypto, MAC, DigitalSignature and KeyExchange

–  No handshakes anymore •  Secure envelopes

–  Data protected by encrypKon using AES-‐CTR (as before) –  MAC can be used for whole RTPS message (as before) –  MAC can be used for part of RTPS message (new)


Agenda



•  Some details



Tokens are a generic mechanism to pass informaKon between DDS and SPIs Token interpretaKon defined by SPI ImplementaKons Some tokens are propagated via DDS


Token RepresentaKon


typedef string<> TokenClass; typedef string<> TokenWrappingClass;

struct DDS_Property { char *property_name; char *property_value; };

struct DDS_Token { TokenClass token_classid; WrappingClass wrapping_classid; DDS_PropertySeq properties; DDS_OctetSeq value; DDS_OctetSeq wrapped_value;

};

AuthenKcaKon


AuthenKcaKon SPI


MR# 6.5.2

BuilKn DDS:Auth:PKI-‐DSA-‐DH

•  Uses shared CerKficate Authority (CA) – All ParKcipants pre-‐configured with shared-‐CA

•  Performs mutual authenKcaKon between discovered parKcipants using the Digital Signature Algorithm (DSA)

•  Establishes a shared secret using Diffie-‐Hellman.


ConfiguraKon of Auth:PKI-‐DS-‐DH

•  Three things: –  X.509 cerKficate that defines the shared CA. This cerKficate contains the Public Key of the CA.

–  RSA private key of the DomainParKcipant. – An X.509 cerKficate that chains up to the CA, that binds the DomainParKcipant public key to the disKnguished name (subject name) for the parKcipant and any intermediate CA cerKficates required to build the chain

•  ConfiguraKon API outside scope of specificaKon – Vendors can use file, QoS property, etc.


Behavior of Auth:PKI-‐DS-‐DH

•  validate_local_parKcipant –  IdenKtyCredenKalToken has X.509 cerKficate – Validates cerKficate against CA

•  validate_remote_parKcipant – Receives X.509 cert of remote parKcipant in IdenKtyToken

– Validates X.509 cert against CA – Does 3-‐message handshake to:

•  verify possession of private key •  establish SharedSecret



Remote ParKcipant AuthenKcaKon

ParKcipants receive X.509 Cert of remote parKcipant via discovery


Each ParKcipant calls validate_remote_idenKty() this checks remote X.509 Cert against locally-‐configured CA

ParKcipant with highest GUID returns PENDING_HANDSHAKE_REQUEST, the other PENDING_HANDSAHKE_MESSAGE



ParKcipant1 creates CHALLENGE1 = “CHALLENGE:<nonce> and sends message via ParKcipantMessageWriter with MessageToken := {CHALLENGE1}



ParKcipant2 creates CHALLENGE2 := CHALLENGE:<nonce> ParKcipant2 sends to ParKcipant1 message with MessageToken := {SIGN(CHALLENGE1), CHALLENGE2}



Part1 verifies SIGN(CHALLENGE1) using Part2’s PK Part1 computes a SharedSecret Part1 sends message with contents: MessageToken := {SIGN(CHALLENGE2), ENCRYPT(SharedSecret)} Encrypt uses Part2’s PK.



Part2 verifies SIGN(CHALLENGE2) using Part1’s PK Part2 decrypts SharedSecret using its own PK

We have Mutual Authen:ca:on and a SharedSecret


Access Control


Access Control SPI


MR# 6.5.2

BuilKn DDS:AC:PKI SPI

•  Configured with: –  X.509 CerKficate of shared Permissions CA –  PermissionsCredenKalToken

•  PermissionsCredenKalToken contains –  XML file with permissions –  Includes SubjectName matching the one on IdenKtyCredenKalToken

– All signed by Permissions CA

This binds the permissions to the idenKty established by the AuthenKcaKonPlugin


Example Permissions


Cryptographic


Crypto-‐AES-‐CTR-‐HMAC-‐DSA-‐DH

•  EncrypKon uses AES in counter mode –  Similar to SRTP, but enhanced to support mulKple topics within a single RTPS message and infrastructure services like a relay or persistence

•  Use of counter mode turns the AES block cipher into a stream cipher –  Each DDS sample is separately encrypted and can be decrypted without process the previous message

•  This is criKcal to support DDS QoS like history, content filters, best-‐efforts etc.

•  DSA and Diffie-‐Hellman used for mutual authenKcaKon and secure key exchange


MR# 6.5.3

BuilKn DDS:Crypto-‐AES-‐CTR-‐HMAC-‐DSA-‐DH SPI

•  Shared secret used to create a KeyExchangeKey •  KeyExchangeKey used to send following Master Key Material using the

BuilKnPublicaKonWriter: –  MasterKey –  MasterSalt –  MasterHMACSalt

•  Based on this the following Key Material is computed: –  SessionSalt := HMAC(MasterKey,"SessionSalt" + MasterSalt + SessionId + 0x00) [ Truncated to 128 bits] –  SessionKey := HMAC(MasterKey,"SessionKey" + MasterSalt + SessionId + 0x01) –  SessionHMACKey := HMAC(MasterKey,"SessionHMACKey" + MasterHMACSalt + SessionId) Note: SessionId goes on the EncryptedMessage Envelope

•  EncrypKon uses AES in Counter (CTR) mode –  The session counter is sent on EncryptedMessage Envelope.


Conclusion •  Submission revised based on addiKonal implementaKon experience

•  Plugin APIs modified to enhance performance and support implementaKons that want to use MIKEY exchanges and SRTP style encrypKon

•  A few things are sKll missing –  IDL for interfaces – Wire protocol parameter-‐ID assignment –  Resolve inconsistencies in document –  Examine is there are special rules that affects ParKKons

•  TargeKng June 2013 for vote to recommend adopKon


Find out more… www.rK.com

community.rK.com

demo.rK.com

www.youtube.com/realKmeinnovaKons

blogs.rK.com

www.twiRer.com/RealTimeInnov

www.facebook.com/RTIso`ware

www.slideshare.net/GerardoPardo

dds.omg.org

www.omg.org

© 2012 RTI • ALL RIGHTS RESERVED 69

omg dds security. 4th revised submission

Technology

realtime innovakons

dds security rfp

dds topic

dds independent

dds parkkon

dds discovery data

dds domain

dds applicakons