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Voice securityprotocol review



This talk is a intense overview of major voice security and encryption protocols existing out there for different scope.

This talk is a intense overview of major voice security and encryption protocols existing out there for different scope.



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  • http://gsmsecurity.blogspot.com/2009/05/a53-or-kasumi-encryption.html

Voice securityprotocol review Presentation Transcript

  • 1.
    • Major Voice Security protocol Review
    • Voice Security Protocol Review
    An overview of all major voice security protocols like never done Fabio Pietrosanti (naif) Email: [email_address] Blog: http://infosecurity.ch
  • 2. Agenda: Mission impossible in 1 hour?
    • 1 – Understanding voice encryption
    • 2 – Mobile TLC industry standards
    • 3 - Government and Military standards
    • 4 - Public Safety standards
    • 5 - IETF VoIP Security standards
    • 6 - Various anti-wiretapping secure phones
    • 7 - Conclusion
    • From this talk you will learn a lot about:
    • Different requirements among voice encryption technologies
    • Major voice encryption standards
  • 3. Who am i Fabio Pietrosanti
    • Works in IT Sec till ’98
    • Stay in digital underground with nickname “naif” till ’95
    • Worked as network security manager for I.NET SpA, Security Advisor Corporate Security Telecom Italia
    • Now CTO of KHAMSA ITALIA SPA doing voice encryption stuff http://www.privatewave.com
    • Project and engineer strong encryption products and technologies for VOICE
    • Technology partnership with Philip Zimmermann
    • Participate to underground communities, sikurezza.org, s0ftpj, metro olografix, progetto winston smith, etc
  • 4.
    • Being founder and CTO of a company doing voice encryption this presentation follow my view on encryption and security/wiretapping technologies
    • My personal and professional feeling are about voice crypto are philosophically near to openness, standardization open-source, open and transparent peer review and i hate every closed and proprietary solution
    • This presentation try to be as much as objective as possible
  • 5.
    • 5
    • Overview of voice encryption systems
  • 6. Communication technologies
    • Traditional telephony (circuit switched)
      • ISDN (fixed)
      • PSTN (fixed)
      • GSM/CDMA/UMTS (mobile)
      • SAT (iridium, turaya, inmarsat, etc)
    • VoIP Telephony (packet switched)
      • Softphone on PC
      • Hardware phones
      • Mobile internet (GPRS, EV-DO, EVDO, etc)
    • Radio transmission
      • HF, UHF, EHF, VLF (air, space, earth, sea)
    Understanding voice encryption
  • 7. Authorities for standards
    • ISO
    • ITU-T
    • GSM Consortium
    • 3GPP
    • 3GPP2
    • NSA
    • NATO
    • IETF
    • Telecom Industry Association (US interim standards)
    Understanding voice encryption
  • 8. Result of complexity in technologies and authorities
    • NO single standard for telephony
    • NO single standard for security (not even enough!)
    • And most persons just think that only Internet exists…!
    Understanding voice encryption
  • 9. Digital vs. Analog
    • Scrambling Vs. Encryption
    • Analog connection Vs. Digital connection
    • Creating a digital data path over the media
    • And what about the signaling?
      • Outband signaling
      • Inband signaling
    • Best review of scrambling technologies with security evaluation: https://upcommons.upc.edu/pfc/bitstream/2099.1/4858/1/MarkusBrandau.pdf
    Understanding voice encryption
  • 10. TLC Communication technologies
    • But bear in mind military and public safety requirement: Radio from ELF (3-3000hz) to EHF (30-300ghz)
    Understanding voice encryption Data Transmission Circuit Switched Packet Switched ISDN, GSM,CDMA,UMTS, PSTN, SAT VoIP Quality of service Granted GPRS / EDGE / UMTS Not Granted Coverage Full Only Urban Area Billing Per-second (sender pay) Per-packet (sender/receiver pay) Signaling Outband In-band (over IP)
  • 11. Different use case and requirements
    • Government (embassies and agencies) and Military (battlefield, earth, air, sea)
    • Public safety
    • Mobile Telecommunication industry
    • IETF standards
    • Misc use anti-wiretapping secure phone
    Understanding voice encryption
  • 12. Major technology summary Understanding voice encryption Use case Technology End-To-Site Security End-to-En Security Government and Military SCIP Yes Yes Public Safety TETRA Yes Yes (optional) Mobile Industry GSM UMTS LTE Yes No IETF (Internet) SRTP/SDES SRTP/ZRTP Yes Yes
  • 13. Different security model
    • End-to-end Security
      • point-to-point
      • point-to-multipoint
    • End-to-site
    • Mixed setup
    Understanding voice encryption
  • 14. Security of crypto operation
    • Tamper proof encryption key container (SIM Card)
    • Tamper proof enciphering hardware (NSA / NATO Crypto Card)
    • Embedded hw/sw encryption along with tlc equipment
      • General Trusted operating system
      • General operating system
      • Embedded custom (firmware) operating system
        • False sense of security using old concepts
        • Jtag debugging & reversing are currently diffused
        • Firmware can be broken if not protected with trusted hardware
    Understanding voice encryption
  • 15. Standards vs Proprietary
    • Moving from a cold-war to multilateral operations bring to standardization and interoperability requirements
    • Proprietary technology
      • Require gateway for interoperability breaking end-to-end security
      • Increase delay
      • High costs
      • Single vendor dependency
    • Standards and open technologies
    • Standards but closed technologies
    • Standards but partially closed technologies
    Understanding voice encryption
  • 16. NSA Cryptographic Modernization Program
    • Moving from proprietary to standard solution
    • Interoperate with NATO and coalition
    • Replacing 1.3milion encryption units in 10 years
    • Avoid dependency on single vendor
    • Reduce costs
    • Update all equipments to modular crypto systems
      • Not anymore single crypto system but modular upgradable systems
    Understanding voice encryption
  • 17. The race to standardization
    • Mobile TLC industry:
      • GSM 2G: A5/1 , A5/2, A5/3
      • GPRS 2.5G: GEA1, GEA2, GEA3
      • UMTS 3G: UEA1, UEA2
      • UMA/GAN: IPSEC with IKEv2 / AES
      • LTE 4G: 128-EEA1, 128-EEA2, 128-EEA3
    • Government and Military: SCIP / FBNDT
    • Public safety: TETRA
    • IETF Standard: SIP/RTP (SRTP -> SDES / ZRTP / DTLS)
    • Secure Phone: Still plenty of various proprietary solution
    Understanding voice encryption
  • 18. Beware of Snake Oil Crypto
    • Staying careful about snake oil encryption
    • Bruce Schneier and Phil Zimmermann reference
    • Snake Oil Encryption is
      • Secret Algorithm
      • Algorithm without key exchange details
      • Security Expert review and useless certificates
      • Unbreakable
      • Unsubstantiated bit claims
      • Not explaining the security model (end-to-end vs end-to-site)
    • http://en.wikipedia.org/wiki/Snake_oil_(cryptography )
    • http://www.interhack.net/people/cmcurtin/snake-oil-faq.html
    Understanding voice encryption
  • 19.
    • Mobile TLC Industry
    • GSMA / 3GPP / LTE
  • 20. Security by lobbying and patenting Mobile TLC industry
    • TLC industry is represented mainly by large corporation
    • Each standard is defined inside defined organization with the direct industry participation
    • Standards are specifically defined in a cryptic and complex document formats
    • Standards in mobile environment are very often plenty of patented methodologies
    • Even if we refer always to “GSM” there are a lot of GSM releases
    • Information is fragmented and the “Algorithm” custodian concept prevent immediate use for research
    • http://gsmworld.com/our-work/programmes-and-initiatives/fraud-and-security/gsm_security_algorithms.htm
  • 21. 2G: GSM encryption Mobile TLC industry
    • Operate at Layer1
    • Provide one-way mobile to network authentication
    • Provide mobile-to-BTS encryption
    • A wide set of algorithms
      • A5/0 (no encryption)
      • A5/1 (standard encryption)
      • A5/2 (export version, weak)
      • A5/3 (Use of Kasumi in GSM)
    • Given the peculiarity of the overall protocol all GSM communication can be broken, even with an upgrade to A5/3, because interoperability and compatibility has to be kept and most mobile phones cannot be upgraded
  • 22. 2.5G: GPRS/EDGE Encryption Mobile TLC industry
    • Operate at Layer2 (LLC)
    • Does not have any relationship with A5/1 or A5/2 of GSM
    • Algorithm used:
      • GEA0 (no encryption)
      • GEA1 (export controlled)
      • GEA2 (normal strength)
      • GEA3 (GPRS use of Kasumi)
  • 23. 3G: UMTS encryption Mobile TLC industry
    • UMTS use two set of algorithms:
      • UEA1 and UIA1, based on Kasumi
      • UEA2 and UIA2, based on SNOW 3G
    • In UMTS there is a mutual authentication between handset and the network
    • In 2005 it has been demonstrated 1 st an attack (yet not so practical) against KASUMI
    • In 2010 it has been demonstrated the recovery of full key against Kasumi, but still not practical for how it’s used in 3G systems
    • Have a look at http://eprint.iacr.org/2010/013
  • 24. 4G: LTE multiple encryption Mobile TLC industry
    • LTE is a still a work-in-progress protocol
    • It follow a completely different approach respect to 2G and 3G:
      • Supporting a multiple set of conceptually different encryption algorithms to be able to resist against a single attack
      • 128-EEA1 and 128-EIA1 (identical to UMTS UEA2 and UIA2 based on SNOW)
      • 128-EEA2 and 128-EIA2 (based on AES)
      • 128-EEA3 and 128-EIA3 (based on ZUC)
      • Extend USIM key length up to 256-bit
    • Mandatory Backhaul protection (BTS/BSC -> MSC)
    • Mandatory TS 33.401 Security Architecture for LTE
  • 25. UMA / GAN Mobile TLC industry
    • Trough UMA (Unlimited Mobile Access) / GAN (Generic Access Network), roaming between 2G/3G and IP network
    • UMA reuse as-is IETF available standards
      • IPSEC with IKEv2 key exchange
      • 3DES/AES encryption
      • NAT-T IPSEC tunneling
      • EAP-SIM for authentication with SIM
      • EAP-AKA for authentication with USIM
  • 26.
    • Government and Military
    • NATO / NSA
  • 27. Intro
    • Government always used to keep encryption algorithm and protocols secrets
      • Multiple different communication protocol
      • Multiple different security protocols
      • Multiple different cryptographic suites
      • Multiple different key management system
    • Current multilateral context is changing
    • Budget reduction and military cooperation lead to interoperability requirements
    Government and Military
  • 28. SIGSALY Secure Voice System Circa 1943, SIGSALY provided perfect security for secure voice communication among allies. Twelve units were built and deployed in Washington, London, Algiers, Brisbane , Paris ….. Reference: SCIP, Objective, History and Future Development: Veselin Tselkov Government and Military
  • 29. Sylvania’s ACP-0 (Advanced Computational Processor) Circa 1966, the ACP-0 was the first programmable digital signal processing computer. A 12-bit machine, it was used to program modems, voice and error control coders. One unit was built, leading to the ACP-1, a 16-bit machine. Reference: SCIP, Objective, History and Future Development: Veselin Tselkov Government and Military
  • 30. Sylvania’s PSP (Programmable Signal Processor) Circa 1970, the PSP was Sylvania’s third generation programmable digital signal processing computer. A 16-bit machine. The PSP led to the STU-I. Reference: SCIP, Objective, History and Future Development: Veselin Tselkov Government and Military
  • 31. STU-I Circa 1979, the STU-I used the PSP digital signal processing computer. A few hundred units were eventually deployed. Reference: SCIP, Objective, History and Future Development: Veselin Tselkov Government and Military
  • 32. Original STU-II Circa 1982, the STU-II provided 2400 and 9600 bps secure voice. A few thousand units were eventually deployed. Reference: SCIP, Objective, History and Future Development: Veselin Tselkov Government and Military
  • 33. First interoperability attempt
    • US STU-II was first device set interoperable with NATO NBSV-II devices
    • But in 1985 NSA initiated FSVS (Future Secure Voice System) and created in 1987 STU-III ISDN voice encryption Units
    Government and Military Selex BRENT BRENT And the story repeat again… broken interoperability with European NATO partners! German TopSec-703
  • 34. But again in the ‘90 STE appeared!
    • A new architecture for secure telecommunication for multi-media communication lines (Radio, ISDN, Satellite)
    • STE works by completely avoiding internal crypto operations with KOV-14 Fortezza Plus Crypto Card
    Government and Military
    • Since 2004 STE are currently the official voice encryption device of US, with firmware upgrade to support SCIP, VoIP and for a variety of new Crypto Card:
    • KSV-21 – Type 1 TOP Secret USA
    • KSV-40 – NATO TOP Secret
    • SSV-50 – Coalition Partners
    • KSV-30 – CCEB (Australia, New Zealand, UK, US, Canada)
  • 35. Finally standard telephony: FNBDT / SCIP
    • In 1997 Future Narrow Band Digital Terminal (FNBDT) project is started in the US to create a multiple media and interoperable voice secure communication protocol
      • Baton 320-bit NSA secret symmetric crypto algorithm
      • Firefly key exchange for EKMS (standardized as Photuris RFC2522)
    • In 2003 it has been proposed for use within NATO, with the creation of IICWG interworking group
    • In 2004 it has been renamed to Secure Communication Interoperability Protocol (SCIP)
      • AES for symmetric encryption
      • Extended key exchange with Enhanced Firefly
    Government and Military
  • 36. SCIP: Tech sheet
    • Application layer secure telephony protocol (L7)
    • Works over any media (Radio, GSM, ATM, ISDN, SATCOM)
    • Use MELPe codec (600-2400bit/s) or G.729D (5300bit), royalty free only for US Government and NATO
    • Allow the implementation of custom proprietary symmetric and asymmetric encryption system while keeping interoperability
    • Example multi-vendor interoperable Voice infrastructure
    Government and Military
  • 37. NSA EKMS
    • The Electronic Key Management System of NSA has been adopted as a standard for the handling of key distribution and authentication
    • EKMS is based on Enhanced Firefly (Photuris RFC specification)
    • Periodic Re-keying is required by policy (OTAR)
    • EKMS Is tier-based hierarchy… do you remember x509v3 PKI? :-)
    Government and Military
  • 38. SCIP: Where are the specification?
    • It’s the typical not-so-open but standard technology
    • Googling tell you something about what to look for:
      • FNBDT-120 – Key Management Plan
      • FNBDT-230 Cryptographic Specification
      • FNBDT-220 Conditions for interoperability
      • SCIP-231 AES Encryption
    • But no official public document other than….
      • Check http://nc3a.info/MDS/FNBDT/FNBDT_NATO_BriefV9.ppt
        • FNBDT Signaling schematics!!!
      • Check http://www.dtic.mil/dticasd/sbir/sbir041/srch/sbir147.html
        • FNBDT 1999 partial initial specification document!!!!!
    Government and Military
  • 39. SCIP protocol stack view Government and Military
  • 40. Some SCIP Manufacturer
    • US - NSA, General Dynamic, L3 Communications
    • UK – QinetiQ, DSTL
    • DE – BSI, R&S
    • IT – SELEX
    • ES – GS, Technobi
    • RO – Electromagnetica
    • NATO – NHQC3S, NC3A
    Government and Military
  • 41.
    • Public Safety
    • European ETSI standard for an interoperable world
  • 42. From analog scrambler….
    • First encrypted radio was using unsecure voice frequency inversion (scrambling)
    • RSA and Diffie-Hellman was born trying to create syncronization methods from scramblers
    • Scramblers cannot be secure as they don’t do encryption
      • Often referred scrambler are digitizer (modem) that over the digital path make encryption
    • Scrambler has been cracked in a lot of countries with simple PC software
    • Frequency Hopping Radio transmission techniques (TRANSEC) has been added to modern radio security techniques to increase security at layer1
    Public Safety
  • 43. To TETRA (1)
    • Designed as ETSI standard Terrestrial Trunked Radio
    • (but France has it’s own TETRAPOL variant)
    • Used in +35 nations (not only europe but also Russia, India, Brazil, Argentina, etc)
    • Operate on 400mhz on a different infrastructure
    • 0.5s call setup
    • Provide IP packet transport over tetra
    • Operate without a network with Direct Mode Operations
    • Each device is able to works as a independent repeater
    Public Safety
  • 44. To TETRA (2)
    • Signaling is encrypted
    • Voice and Data are encrypted
    • Similar to GSM with Ki private secret residing on SIM or on Trusted Mobile device
    • Support for mutual authentication with the network
    • Support point-to-point and point-to-multipoint end-to-end encryption
    • Release:
      • 1994 Formation of Tetra consortium
      • 1999 Tetra Release 1
      • 2005 Tetra Release 2 (+AMR +CELP +Extended DMO)
    Public Safety
  • 45. TETRA encryption algorithms
    • Tetra Authentication Key Management Algorithm: TAA1
    • Algorithm for encryption (secret codes):
      • TEA1: 1 st exportable Tetra algorithm (distributed by ETSI)
      • TEA2: 1 s strong encryption for schengen countries (distributed by Dutch Police IT Organization)
      • TEA3: 2 nd strong encryption for schengen countries (distributed by ETSI)
      • TEA4: 2 nd exportable Tetra algorithm (distributed by ETSI)
    • Support end-to-end encryption with IDEA, AES and custom algorithms
    • http://www.tetramou.com/uploadedFiles/Files/Documents/Overviewofstandardcryptographicalgorithms.pdf
    • http://www.tetramou.com/uploadedFiles/About_TETRA/TETRA%2520Security%2520pdf.pdf
    Public Safety
  • 46. TETRA encryption configuration
    • Clear (no air interface encryption) without End to End Encryption
    • TETRA Encryption Algorithm 1 (TEA1) without End to End Encryption
    • TETRA Encryption Algorithm 2 (TEA2) without End to End Encryption
    • TETRA Encryption Algorithm 3 (TEA3) without End to End Encryption
    • Clear (no air interface encryption) with End to End Encryption
    • TETRA Encryption Algorithm 1 (TEA1) with End to End Encryption
    • TETRA Encryption Algorithm 2 (TEA2) with End to End Encryption
    • TETRA Encryption Algorithm 3 (TEA3) with End to End Encryption
    Public Safety
  • 47. TETRA BOS digital radio (germany)
    • Example implementation by BSI of the German TETRA network with smartcard security
    • https://www.bsi-fuer-buerger.de/cae/servlet/contentblob/487530/publicationFile/27989/BSI_AnnualReport2005_pdf
    Public Safety
  • 48.
    • IETF VoIP security standards
  • 49. VoIP basic
    • IETF VoIP standard apply to internet and IP based communications
    • SIP is used to transport signaling information
    • RTP is used to carry media traffic (audio, video)
    • Both usually works over UDP protocol
    • SIP can works securely across a TLS secured channel
    IETF VoIP security standards
  • 50. Signaling Encryption: SIP/TLS
    • Provide a secured and network authenticated channel for signaling with TLSv1 (much like HTTPS)
    IETF VoIP security standards
  • 51. Media encryption: SRTP
    • SRTP describe how to encrypt and guarantee the integrity of RTP packets
    • Encryption has been brought to IETF standard in March 2004 with SRTP (RFC3711)
    • Several Key Exchange methods has been standardized
    • SRTP support for symmetric encryption
      • AES128 Counter mode
      • AES128 f8-mode
    • SRTP for integrity checking HMAC-SHA1
      • 32 bit version
      • 80 bit version
    • Upcoming internet-draft fo AES-192 and AES-256
    IETF VoIP security standards
  • 52. Media encryption: SRTP IETF VoIP security standards
  • 53. E2S Key exchange: SDES
    • SDES is the only widely diffused and implemented key agreement method
    • It’s transported over SIP channel protected with TLS
    IETF VoIP security standards
  • 54. E2S Key exchange: SDES packet IETF VoIP security standards INVITE sips:* [email_address] ;user=phone SIP/2.0 Via: SIP/2.0/TLS;branch=z9hG4bK-s5kcqq8jqjv3;rport From: &quot;123&quot; <sips: [email_address] g >;tag=mogkx srhm4 To: <sips:* [email_address] ;user=phone> Call-ID: 3 [email_address] CSeq: 1 INVITE Max-Forwards: 70 Contact: <sip: [email_address] :2049;transport=t ls;line =gyhiepdm> ;reg-id=1 User-Agent: snom360/6.2.2 Accept: application/sdp Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE, PRACK, MESSAGE, INFO Allow-Events: talk, hold, refer Supported: timer, 100rel, replaces, callerid Session-Expires: 3600;refresher=uas Min-SE: 90 Content-Type: application/sdp Content-Length: 477 v=0 o=root 2071608643 2071608643 IN IP4 s=call c=IN IP4 t=0 0 m=audio 57676 RTP/AVP 0 8 9 2 3 18 4 101 a=crypto:1 AES_CM_128_HMAC_SHA1_32 inline:WbTBosdVUZqEb6Htqhn+m3z7wUh4RJVR8nE15GbN a=rtpmap:0 pcmu/8000 a=rtpmap:8 pcma/8000 a=rtpmap:9 g722/8000 a=rtpmap:2 g726-32/8000 a=rtpmap:3 gsm/8000 a=rtpmap:18 g729/8000 a=rtpmap:4 g723/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-16 a=ptime:20 a=encryption:optional a=sendrecv
  • 55. E2E/E2S Key exchange: MIKEY
    • Mikey has been standardized in 2004 as RFC3830
    • Provide a key exchange method for SRTP on the SIP channel via SDP attribute
    • It has been updated with RFC4738 to support other exchange method
    • Mikey support several key exchange method
      • Null
      • Pre-shared keys
      • Diffie Hellman
      • Diffie Hellman HMAC
      • RSA
      • RSA (reverse mode)
    • Given the implementation complexity it never got really deployed
    IETF VoIP security standards
  • 56. End-to-end encryption key exchange for SRTP
    • As a story we all have already seen with OpenPGP/MIME vs. S/MIME there are two competing standards
      • A Hierarchical standard to be integrated within PKI infrastructure - DTLS
      • A non hierarchical standard with a very high level or paranoid feature - ZRTP
    IETF VoIP security standards
  • 57. E2E key exchange - DTLS
      • In March 2006 DTLS (Datagram Transport Layer Security) has been defined to protect UDP streams much like SSL and the successor TLS used in the web world
      • RTP runs over UDP
      • In 2008 a method to use DTLS as a key exchange method of SRTP to encipher RTP packets won the standardization path of IETF
    IETF VoIP security standards
  • 58. E2E Key Exchange: DTLS-SRTP
      • Require a PKI to be used
      • It completely rely on SIP channel integrity
      • In order to keep the SIP channel integrity “Enhanced SIP identity” standard (RFC4475) has to be used .
      • Unfortunately MiTM protection cannot be guaranteed when calling a phone number (+4179123456789) and so DTLS-SRTP collapse in providing security
      • So the basic concept is that DTLS require a PKI to works, with all the burocracy and complexity around building it
      • Most of the vendor that announced to use DTLS-SRTP said that they will provide self-signed certificate
    IETF VoIP security standards
  • 59. E2E Key exchange: ZRTP (1)
      • Mr. Zimmermann did it again and by leveraging the old PGPhone concept of 1995 he designed and proposed for standardization ZRTP VoIP security protocol
      • ZRTP does not use SIP but instead use in a clever way the RTP packet to perform in-band (inside RTP) key handshake
      • The concept is simple: what we need to protect?
        • The media
      • So why modify the SIP signaling increasing complexity?
      • KISS principle always stay ahead
      • Implemented by Philip Zimmermann (zfoneproject.com), Werner Viettmann (gnutelephony.org), MT5 (unknown non-public implementation)
    IETF VoIP security standards
  • 60. E2E Key exchange: ZRTP (2)
      • ZRTP is provided to IETF as a standard (currently in standardization path) as a key initialization method for SRTP
      • ZRTP use different key agreements method inside the cryptographic protocol
        • ECDH (NSA Suite B)
        • DH
        • Preshared Key
      • ZRTP support PFS (Perfect Forward Secrecy)
      • Self-healing key cache (avoid ssh-like attack)
      • Can be used over most signaling protocols that use RTP for media transport (SIP, H.323, Jingle, P2P SIP)
    IETF VoIP security standards
  • 61. E2E Key exchange: ZRTP (3) IETF VoIP security standards
  • 62. ZRTP (4)
      • Short Authentication String as a method to detect MiTM wiretapper
        • the two users at the endpoints verbally compare a shared value displayed at both end
        • If the value don’t match, it indicates the presence of someone doing a man in the middle attack
    IETF VoIP security standards
  • 63. Comparison of key agreements method of SRTP IETF VoIP security standards Technology SDES SRTP - ZRTP SRTP - MIKEY SRTP - DTLS Require signaling security Yes No Depend Yes (with additional complexity) End-to-Site security Yes No Depend Yes End-to-End security No Yes Depend Yes (it depends) Man in the middle protection No Yes Yes Yes (not always) Different implementation in 2010 Yes Yes not widely diffused No
  • 64.
    • Various anti-wiretapping secure phone
    • Misc solutions not fitting precisely in any category
    • (private, business)
  • 65. Too many technologies Various anti-wiretapping secure phone
    • A lot of technologies
    • Extremely fragmented market
    • Companies often based on captive customer group
    • 90% of case no details on custom crypto: Just trust the company!
    • Mainly targeting enterprise and VIP sector
  • 66. A bit of history: clipper, born to fail
    • Clipper Chip was created by White House in 1993 implementing SkipJack algorithm
    • In 1994 FIPS 185 Escrowed Encryption Standard has been approved
    • AT&T release TD3600E
      • 56bit encryption
      • 4800bps data path over PSTN
    • In 1996 the project was considered a complete failure
    • In 1998 skipJack has been declassified
    Various anti-wiretapping secure phone
  • 67. A bit of history: PGPhone
    • In 1995 mr. Philip Zimmermann (2 ‘n) created PGPhone
    • PGPhone was a software for Windows to be used connecting the PC trough a modem an dialing the other party
    • Was using ephemeral Diffie-Hellmann protocol
    • Was using a short authentication string to detect man in the middle attack
    • Unfortunately he was too visionary, in 1996 the internet world was still not ready for such technology
    • In 1997 it became abandon-ware
    Various anti-wiretapping secure phone
  • 68. A bit of history: Cryptophone
    • In 2001 Cryptophone was born and it kept fully open their source code and security protocol design
    • The company (composed of several very good hackers) build up the product and started selling the hardware phones
    • Unfortunately the protocol did not get public attention (also because of lack of independent separated specification/implementation) and did not get strong public auditing nor other interoperable use
    • Now works on CSD and IP
      • No IP specs has been released
    Various anti-wiretapping secure phone
  • 69. ZRTP for CS telephony and Radio ZRTP/S
      • In 2008 Mr. Zimmermann developed jointly with KHAMSA (now PrivateWave) an extension of ZRTP to works again, like PGPhone already does in 1995, over traditional phone lines
      • Resulting product is PrivateGSM CSD (Nokia)
      • ZRTP/S is a communication and security protocol that works over traditional telephony technologies (GSM, UMTS, CDMA IS94a, PSTN, ISDN, SATCOM, BLUETOOTH)
      • Basically it works over a ‘bitstream channel’ that can be easily represented like a ‘serial connection’ between two devices
    Various anti-wiretapping secure phone
  • 70. ZRTP/S Tech sheet
      • ZRTP/S can be, oversimplifying, a subset of a “compatible” RTP packet refactored to works over narrowband channels
      • It works over very narrowband links (4800 - 9600bps)
      • It works over high latency links (GSM CSD and SAT) with a “compressed” ZRTP handshake
      • In order to works over most channel it require the usage of narrowband audio codecs with advanced DTX and CNG features (AMR 4.75, Speex 3.95, MELPe 2.4)
      • Implemented in open source as additional module to libzrtp
      • Soon to be released for public and community usage
    Various anti-wiretapping secure phone
  • 71. Chocolate grade encryption?
    • IMHO most of the remaining systems fit into the category of chocolate grade encryption
      • Just say “We use AES” or “We use DH key exchange”
      • No detailed encryption protocol specs
      • No public review
      • Claim “military-grade” and “unbreakable”
      • Often claim incredible bit size like 16000 bit authentication or 46080 bit encryption
      • Typically no support for PFS
      • Typically vulnerable to local key compromise
    • No, i will not refer to any name here
    Various anti-wiretapping secure phone
  • 72. PIN to protect local keys? Wrong!
    • Example of chocolate grade encryption is with digital certificate system based on user security PIN.
      • You used the best asymmetric crypto
      • You used the best symmetric crypto
      • You designed a complex and full featured enterprise key management system (x509v3)
    • But on mobile device no secure passphrase is possible for frequent use by users
      • Poor keyboard
      • Poor Password
    • As a result the overall security model is strong as much as the PIN strength used to unlock the application that protect the private key
    Various anti-wiretapping secure phone
    • Type a passphrase here:
    • Pa;!sd83/1@sZ
  • 73.
    • Conclusion
  • 74. To summarize
      • Different technologies for different markets and use
      • Market and technologies are fragmented
        • The race to standardization will fire all non standard technologies
      • Most standard technologies include support for proprietary extensions for crypto
      • All standards (TLC, Government, Public Safety and IETF) must be open and not restricted to a wallet garden because of the risk that the history of GSM A5/1 repeat again
  • 75.
    • Major Voice Security protocol Review
    • Voice Security Protocol Review
    An overview of all major voice security protocols like never done Fabio Pietrosanti (naif) Email: [email_address] Blog: http://infosecurity.ch