Overview of CALEA Conformance Proposed Standard PTSC-LAES R6 Manish Karir, Merit – Research and Development

Outline 1.Architectural Assumptions –Internet Access Service Provider Model –Electronic Surveillance Model –Vocabulary Building 2.CALEA Functions –Functional Breakdown of Components –Architecture, Interfaces and Intercept Access Points 3.CALEA conformance –Timing Requirements –CmII/CmC Packet Formats and Encapsulation –General IASP Requirements 4.Re-Cap and Conclusions

Internet Access Services Model Source: PTSC-LAES R6

Internet Access and Services Model Three Aspects to Gaining Access 1. Reg-F - Registration Function: »The act of a user getting access to the network (e.g. login/authentication of any sort) 2. Res-F - Reservation Function: »The user requesting resources from the network (e.g. requesting an IP address, temporary addresses are not included) 3. PT-F - Packet Transfer Function: »Transfer of Layer-3 packets to/from the Internet

Electronic Surveillance Model Components and Responsibilities 1.Service Provider Administration Responsible for the Access and Delivery Functions 2.Access Function (AF) Consists of one or more Intercept Access Points (IAPs) 3.Delivery Function (DF) Transfer of data from the Access Function to the Collection Function 4.Law Enforcement Administration Controls the LEA collection function 5.Collection Function (CF) Location where the communication intercepts are stored Law Enforcement Responsibility Internet Access Service Provider Responsibility

Electronic Surveillance Model Source: PTSC-LAES R6

More Definitions /Acronyms LI - Lawful Intercept CmII - Communication Identifying Information (e.g. packet headers…but more…) CmC - Communication Content (e.g. the packets) IAP - Intercept Access Point Combinations: –AACmII - Access Associated CmII –CACmII - Content Associated CmII –CmC-IAPs - The point in the network where communication content is intercepted –CmII-IAPs - The point in the network where communication headers are intercepted –Note: CmC-IAPs might be different from CmII- IAPs

The 3 Key Concepts 1.CmC - Communication Content –Captured at CmC-IAPs, full packets –Packets are passed to Delivery Function(DF) –The DF transfers these to the LEA Collection Function (CF) 2.AACmII - Access Associated CmII –Essentially login/logout and authorization activity –DHCP IP address assigned –Information provided to CF via the DF cont.

The 3 Key Concepts cont. 3. CACmII - Content Associated CmII - 2 methods –Intercept packet stream to/from subject and extract IP header information, port information is optional,(but might be authorized) finally deliver all header information to DF or deliver summary records –Sample subjects flows such that no flow can exist without being sampled and deliver summary records to LEA

Functional Breakdown CmC/CmII Access Function (AF): –Responsible for identifying/isolating CmC/CmII for the subject and presenting it to the MF/DF CmC/CmII Mediation Function (MF): –Responsible for the presentation of captured information into the appropriate format for delivery to LEA CmC/CmII Deliver Function (DF): –Responsible transmitting data from IASP to the collection function of the LEA

Functional Lawful Intercept Architecture Source: PTSC-LAES R6

Packet Delivery Interface DF-CF Interface Source: PTSC-LAES R6

Intercept Access Points

Delivery Timing Requirements 1.Event Timestamps: Each intercepted message should contain an accurate timestamp –CmII: timestamp should be accurate to within 200ms –CmC: timestamps need to be provided with each packet 2.Event Timing: Intercepted messages should be sent to LEA within specified time window –CmII should be sent by the DF to the CF within 8 seconds 95% of the time –CmC: ???

Timing Requirements Source: PTSC-LAES R6 T1 is dependent in IASP T2 is jointly determined by IASP and LEA by choice of agreed upon protocols and facilities

CmII Access Messages Access Messages: Notify LEA of access related functions performed by the subject including : Access Attempt (login) - subject begins the network authentication process Access Accepted - sent when subject has successfully authenticated with network AAA Access Failed - user provides invalid username/ password or MAC address cont.

CmII Access Messages cont. Access Session End (logout) - subject initiates disconnect Access Rejected - network rejects login attempt e.g. user is already logged in somewhere else and network does not allow multiple logins Signaling Message Report - (RADIUS, DIAMETER, etc.) may be used in place of the previous messages

CmII Packet Data Messages Packet Data Messages: Notify LEA of data related events performed by the subject Packet Data Session Start - sent when subject completes login and and IP address has been assigned Packet Data Session Failed - login is successful but no IP address, e.g. DHCP pool exhausted Packet Data Session End - session timeout

CmII Packet Data Messages Packet Data Messages: Notify LEA of data related events performed by the subject Packet Data Session Already Established - when surveillance starts after subject login Packet Data Header Report - packet header reports on a per-packet basis Packet Summary Report - periodic summary reports of packet header data

Example CmII Message Formats Access Accepted CmII Message Packet Header Data Report CmII Message

CmC Message Delivery Options SCTE Datagram Format ATIS IAS Datagram –Encapsulation Approach - one packet per encapsulated datagram –UDP/IP based encapsulation; TCP or other transport protocols are optional –IC-APDU - Protocol Data Unit Approach - multiple packets per Datagram We focus on the IAS Datagram approach as it is the simplest

IAS Datagram Encapsulation Approach One intercepted packet in each encapsulated UDP datagram Src IP is the address of DF Dst IP is address of CF Port numbers in UDP header may be agreed upon by LEA and IASP ContentID field is ASCII value that allows correlation between CmC and CmII **Timestamp is RFC3339 compliant: YYYY-MDDThh:mm:ss.sssZ **Intercepted Packet includes all headers

IAS Datagram - APDU Approach A simple extension of the encapsulation approach, to include multiple intercepted packets in a single encapsulated packet.

Subject Identification Two Aspects 1.Login Identification: –When network requires authentication prior to use –CmC and CmII is performed only after subject has been identified on the network –After login; subject can be identified via unique IP address or session identifier assigned to subject during login cont.

Subject Identification Two Aspects, cont. 2.Equipment Identification: –When network does not require authentication prior to use –Subject is identified via unique address or interface –Intercept in this scenario may be based on MAC address, IP address or physical/logical port

Six IASP Requirements 1.Privacy: IASP shall not monitor or permanently record subjects communications 2.Isolation: IASP shall ensure that only the subjects communication is intercepted 3.Transparency: IASP shall perform the intercept in a manner such that the subject cannot reasonably detect that intercept is being performed cont.

Six IASP Requirements cont. 4. Encryption/Compression: IASP shall deliver the intercept data unencrypted or provide the LEA with encryption method and keys. IASP shall provide data uncompressed or identify means to decompress 5. Security/Integrity: IASP shall ensure unaltered delivery of intercept data. Security is to be negotiated between IASP and LEA 6. Performance/Quality: IASP should be able to perform multiple intercepts at the same time

Re-cap and Conclusions This is a simplified overview of the standard - Not a substitute for a detailed reading and interpretation. This is a broad introduction to the draft standard. - Terminology used -Rough of the structure of the proposed standard cont.

Re-cap and Conclusions – Remember: 1.The standard itself is unclear in certain areas, for example: –The use of encryption by IASP to protect the CmC –Specifics such as what is the caseID and how is it different from content identifier, IAP system identity, subscriber ID etc. –Implementation details such as what are the sizes of the various fields in the packet headers, what are the timing requirements for CmC delivery 2.Important to remember that it is still a “draft” standard and subject to revision.