Intelligent Agents - Security

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Intelligent Agents - Security

• Katia Sycara
• The Robotics Institute
• email katia_at_cs.cmu.edu
• www.cs.cmu.edu/softagents

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Security for Electronic Commerce
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Insecure Internet

• The original Internet was designed for research,
  not as a commercial environment.
• The TCP/IP protocol suite used by all computers
  connected to the Internet is fundamentally
  lacking in security services.

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Internet Security Weaknesses - 1

• Confidentiality
• Most lower layer protocols, including Ethernet,
  are broadcast in nature machines connected to
  a LAN can eavesdrop on each other
• Nodes lying on the path between two communicating
  parties can eavesdrop on traffic as it passes
• Theft of account information, credit card
  numbers theft of information-based products
• Other info on who talked to whom (even without
  knowing the content involved) leads to loss of
  privacy

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Internet Security Weaknesses - 2

• Authentication
• Virtually impossible to accurately determine
  whether the addresses in data packets are genuine
  or not
• Hosts and users can spoof (impersonate) each
  other
• Integrity
• Packet contents no service provided to
  authenticate the content of packets
• Ex modification of payee of a check the value
  of a check.

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Internet Security Weaknesses - 3

• Repudiation
• parties may deny having participated in
  transaction, sent messages, given authorization,
  etc.
• Hosts need to be protected as well attacks
  targeted to retrieve cleartext information from
  poorly protected systems

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Security Requirements for Commercial Transactions

• Confidentiality
• Authentication
• Data Integrity
• Non-repudiation
• Security mechanisms based on cryptography

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Some Existing Solutions
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Cryptographic Building Blocks - 1

• Symmetric key cryptography
• Two parties share a common secret or key
• Keys are used to encrypt and decrypt messages
• Can be used for authentication with the help of a
  third party.

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Cryptographic Building Blocks - 2

• Public-key cryptographic
• Matching private and public keys
• Can be used to sign and verify signatures

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Public Key Infrastructure

• Ability to match specific keys with their owners
• Public key certificates (Bind public keys to
  specific entities and allow for a third party to
  validate the binding)
• Ex x509 certificate.
• Can be used for encryption and decryption alone

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The Risks of Electronic Commerce - 1

• The customers perspective
• Stolen payment credentials passwords
• Dishonest merchants
• Disputes over service qualities
• Dishonest financial service providers
• Inappropriate use of transaction details.
• The merchants perspective
• Forged or copied instruments
• Disputed charges
• Insufficient funds in customer accounts
• Unauthorized redistribution of purchase items
• Dishonest financial service providers

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Not Everything has a Technical Solution

• There are problems where solutions cant be
  enforced in advance, but where accepted practices
  solve the problem if followed
• privacy protection
• intellectual property rights
• quality of service.
• These practices will usually be followed if
• They are easy to follow
• Social and legal enforcements.

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Other Weak Points

• Hardware
• Operating systems
• System configuration
• System management
• Compilers
• Poorly written software
• Application-level access control
• User neglect

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Adding Security to Retsina
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Why do we need to worry about security?

• We want to deploy our system in open networks
• Agents come and go gt agents interact with
  strangers
• Can agents be trusted? Can their deployers be
  trusted?
• Agents are expected to do more serious things.
  Ex
• Getting info on your banking account
• Carry out sales transactions.

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Assumptions we make

• Neither agents nor their deployers are
  trustworthy (They can misbehave)
• Agents may eavesdrop on communication between two
  other agents
• An agent may masquerade as some other agent
• Agents may not behave as expected (e.g., an agent
  may not want to pay for goods received).
• There must be a few, selected entities that can
  be trusted.

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Adding Security to Retsina (MAS in general)

• Prevent misbehaviors from happening have
  recovery mechanisms if they happen
• Identify different security issues that MAS face
• Propose solutions for these problems
• Design and implement a security infra-structure
  for Retsina.
• Focus application-independent issues
• Communication security yes
• Fair exchange in electronic sales no.
• Approach Standard security techniques used in
  distributed systems
• Authentication
• Access control
• etc.

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Security Threats in MAS

• System-level threats Those that subvert
  inter-agent interactions, independently of the
  application a system is running.
• Untrustworthy ANSs and matchmakers
• Untrustworthy application agents
• Insecure communication channels.
• Application-level threats Those that subvert the
  security of applications. They may exist even if
  the underlying system of agents is secure.
• Service providers that do not implement
  appropriate access control policies
• Untrustworthy application agents.

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Our Solution (1)

• To guarantee the integrity of naming and
  matchmaking services
• Include access control
• ltusegt trusted ANSs and matchmakers!
• Make agents uniquely identifiable, and give them
  unforgeable proofs of identity
• Prevents spoofing
• Make deployers of agents liable for the actions
  of their agents
• Agents are given proofs of identity only when
  deployers allow their own identities to be linked
  with those of their agents.

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Our Solution (2)

• Protect communication channels
• Add access control mechanisms (which usually rely
  on the delegators Ids)
• Make agents prove that they are delegates of whom
  they claim to be.

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A Design of a Security Infra-structure for Retsina

• Assumptions
• Deployers have public key certificates binding
  their physical identities (SSN, company names,
  etc.) to their public keys
• DCAs are assumed to exist (lie outside our
  security infra-structure)
• ANSs and matchmakers
• are trusted entities
• their public keys are publicly known.
• The addresses of ANSs are publicly known.

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Public Key Cryptography

• Key pairs
• Private keys a
• Public keys A pub(a)
• Digital signatures (m)a
• Signature verification
• Use A to verify (m)a
• Public key certificates
• (Name, Public key)ca

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Giving Identities to Agents Establishing
Liability (1)

• 1. Choose an Agent ID AID
• 2. Generate a public key pair a, pub(a)
• 3. m1(certify AID,pub(a),t)d
• 4. Verify the validity of the request
• 5. Generate m2ACA-signed certificate binding
  pub(a) to AID
• 6. Creates an entry Ds public key certificate,
  m1 in the certification DB
• 8. Verify the signature in m2 with ACAs public
  key.

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Giving Identities to Agents Establishing
Liability (2)

• Agents are given
• a public key certificate, and
• a matching private key.
• The certification process
• certification can be requested only by deployers
  who can prove their own identities gt make the
  deployer aware of his or her liabilities.

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Revoking an Agents Public Key
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Registering at an ANS
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Unregistering at an ANS
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The Lookup Protocol

• Agents are identified by their keys, and not
  their names!!

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Matchmaker Protocols

• Very similar to ANS protocols
• Differences
• Physical addr may not be shared by more than one
  agent capabilities may
• Agents use ANSname.Agentname to register with the
  matchmaker
• The lookup protocol
• 1. CAP
• 2. CAP, ANS-x1.AID1,CERT1, ANS-xn.AIDn,
  CERTn, Tmm

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Secure Communication Channels

• SSL (Netscapes Secure Socket Layer protocol)
• Why?
• Keep communication security transparent from the
  application
• Off-the-shelf trustworthy technology (extensible
  too).
• Implementation
• Local effort at the Communicator.

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Secure Delegation Access Control

• Knowing who is the delegator may be necessary or
  desirable
• Original design Have the agent know the secret
  key of its deployers
• Weaknesses
• Agents should not know such important secrets
• Sometimes they do not even have to know (ex
  PIN)
• Should have a weaker, temporary solution.

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Some Interesting Pages

• http//microsoft.com/security/tech/certificates/fo
  rmats.asp
• Some introductory material on standards for
  cryptographic object
• http//security.dstc.edu.au/projects/java/release3
  .html
• Info on a real-world security package (can
  download the code and play)
• Communications of the ACM - June 1996, volume 39,
  Number 6
• An issue dedicated to EC from which the article
  is extracted.