SIP Security Issues : The SIP Authentication Procedure and its Processing Load
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Transcript of SIP Security Issues : The SIP Authentication Procedure and its Processing Load
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SIP Security Issues :The SIP Authentication Procedure and its Processing Load
Speaker: Lin-Yi WuAdvisor : Prof. Yi-Bing LinDate : 2003/04/09
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Main Reference
Salsano, S.; Veltri, L.; Papalilo, D , “SIP security issues: the SIP authentication procedure and its processing load “, IEEE Network , Volume: 16 Issue: 6 , Nov/Dec 2002
J. Rosenberg et al., “SIP: Session Initiation Protocol “ IETF RFC 3261, June 2002
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Outline
Motivation Classification of security
End-to-End Hop-by-Hop
Security Support in SIP Authentication Encryption
Evaluation of Processing Cost Proposed solution
Requirements Limitation of current SIP security mechanism Design concept
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Motivation
Achieve the same security level in PSTN High service availability
Prevent DOS, IDS, fault tolerance…etc. Protection of user-to-network and user-
to-user traffic Authentication Data Integrity Encryption
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Classification of security mechanism
End-to-End mechanism Secure association between caller and callee user agent Protect any confidential information besides route infor
mation Hop-by-Hop mechanism
Secure association between two successive SIP entities in the path
Protect route information
UACUAS
SIP Server SIP Server
SIP Server
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Security Support in SIP
End-to-End mechanism Defined in SIP protocol
Authentication Proxy-Authenticate, Proxy-Authorization, WWW-Authenti
cate, Authorization Encryption
S/MIME Hop-by-Hop mechanism
Rely on Network level or Transport Level security IPSec TLS
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Evaluation of Authentication Processing Cost
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Analysis :SIP Authentication Requirements
Requirements Authentication
Mutual Authentication Key Distribution Roaming agreement
Integrity Cipher Key exchange Prevention of replay attack
Limitation of current Authentication mechanism Authentication
Mutual Authentication : NO Key Distribution : Predefine secret Roaming agreement : NO
Integrity : achieve by S/MIME Cipher Key exchange : NO Prevention of replay attack : achieve by nonce
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Concept of Design :Public/Private key based Authentication
The public key /private key of A : Pub_A/Pri_A The public key /private key of B : Pub_B/Pri_B A knows B’s public key Pub_B B knows A’s public key Pub_A
Nonce1
(response1,nonce2)
response1 = Pri_A (nonce1+1)
response2 =Pri_B(nonce2+1)
Verify response1by Pub_A
(response2)
Success
A B
Verify response2by Pub_B
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Concept of Design : Certificate-based authentication (1/2)
Only CA’s public key has to be known.
NCTU
DB
CA_NCTU
SIP proxy1
SIP proxy2
UAC
Cr_Proxy1
Pub_CA_NCTU
Cr_Proxy2
Pub_CA_NCTU
Cr_UAC
Pub_CA_NCTU
INVITE
Authenticate required(Cr_Proxy2, nonce1)
(Cr_UAC, response1,nonce2)
Verify Cr_Proxy2by Pub_CA_NCTU=> Get Pub_Proxy2
response1 = Pri_UAC (nonce1+1) Verify Cr_UAC
by Pub_CA_NCTU=> Get Pub_UAC
response2 =Pri_Proxy2(nonce2+1)
Verify response1by Pub_UAC
(response2)
INVITE
UAC SIP proxy 2
Verify response2by Pub_Proxy2
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Roaming agreement
NCTU
DB
CA_NCTU
SIP proxy1
SIP proxy2
NTU
DB
CA_NTU
SIP proxy4
SIP proxy3
UAC
Cr_Proxy1
Pub_CA_NCTU
Cr_Proxy2
Pub_CA_NCTU
Cr_UAC
Pub_CA_NCTU
Cr_Proxy4
Pub_CA_NTU
Cr_Proxy3
Pub_CA_NTU
Concept of Design : Certificate-based authentication (2/2)
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Roaming agreement
NCTU
DB
CA_NCTU
SIP proxy1
SIP proxy2
NTU
DB
CA_NTU
SIP proxy4
SIP proxy3
UAC
Cr_Proxy1
Pub_CA_NCTU
Cr_Proxy2
Pub_CA_NCTU
Cr_UAC
Pub_CA_NCTU
Cr_Proxy4
Pub_CA_NTU
Cr_Proxy3
Pub_CA_NTU
Cr_CA_NTUCr_CA_NCTU
Cr_CA_NTU
Cr_CA_NTU
Cr_CA_NCTU
Cr_CA_NCTU
Pub_CA_NTU
Pub_CA_NTU
Pub_CA_NCTU
Pub_CA_NCTU
Concept of Design : Certificate-based authentication (2/2)
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INVITE
Authenticate required(Cr_CA_NTU,Cr_Proxy4, nonce1)
(Cr_UAC, response1,nonce2)
Verify Cr_Proxy4by Pub_CA_NTU=> Get Pub_Proxy4
response1 = Pri_UAC (nonce1+1)
Verify Cr_UACby Pub_CA_NCTU=> Get Pub_UAC
response2 =Pri_Proxy4(nonce2+1)
Verify response1by Pub_UAC
(response2)
INVITE
UAC SIP proxy 4
Verify Cr_CA_NTUby Pub_CA_NCTU=> Get Pub_CA_NTU
Verify response2by Pub_Proxy4
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Examine the Requirements Authentication
Mutual Authentication : YES Key Distribution : base on Certificate verification Roaming agreement : solved by PKI architecture
Integrity : S/MIME Cipher Key exchange : can be achieved by
public key & private key system Prevention of replay attack : achieve by nonce
New type of Headers have to be specified.
Concept of Design:Examine the requirements
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The EndThe End
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Authentication ProcedureINVITE
407 Proxy-Authentication RequiredProxy-Authenticate(nonce1)
ACK
INVITEProxy-Authorization (nonce1, response1)
response1 =F(nonce1,secret1)
INVITEINVITE
401 UnauthorizedWWW-Authenticate(nonce2)
Verifyresponse1
401401
ACKACK
ACKINVITE
Authorization (nonce2, response2)
INVITE
response2 =F(nonce2,secret2)
Verifyresponse2
INVITEAuthorization (nonce2, response2)
180 ringing180
180200
200
200 OK
ACKACK
ACK
UASSIP ProxySIP ProxyUAC
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S/MIME INVITE sip:[email protected] SIP/2.0 Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bKnashds8 To: Bob <sip:[email protected]> From: Alice <sip:[email protected]>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314159 INVITE Max-Forwards: 70 Contact: <sip:[email protected]> Content-Type: application/pkcs7-mime; smime-type=enveloped-data; name=smime.p7m Content-Disposition: attachment; filename=smime.p7m handling=required
Content-Type: application/sdp v=0 o=alice 53655765 2353687637 IN IP4 pc33.atlanta.com s=- t=0 0 c=IN IP4 pc33.atlanta.com m=audio 3456 RTP/AVP 0 1 3 99 a=rtpmap:0 PCMU/8000
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SIP Header Privacy and Integrity using S/MIME : Tunneling SIP
INVITE sip:[email protected] SIP/2.0 Via: SIP/2.0/UDP pc33.atlanta.com; branch=z9hG4bKnashds8 To: Bob <sip:[email protected]> From: Alice <sip:[email protected]>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314159 INVITE Max-Forwards: 70 Date: Thu, 21 Feb 2002 13:02:03 GMT Contact: <sip:[email protected]> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary=boundary42 Content-Length: 568
--boundary42 Content-Type: message/sip
INVITE sip:[email protected] SIP/2.0 Via: SIP/2.0/UDP pc33.atlanta.com; branch=z9hG4bKnashds8 To: Bob <[email protected]> From: Alice <[email protected]>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314159 INVITE Max-Forwards: 70 Date: Thu, 21 Feb 2002 13:02:03 GMT Contact: <sip:[email protected]> Content-Type: application/sdp Content-Length: 147
v=0 o=UserA 2890844526 2890844526 IN IP4 here.com s=Session SDP c=IN IP4 pc33.atlanta.com t=0 0 m=audio 49172 RTP/AVP 0 a=rtpmap:0 PCMU/8000
--boundary42 Content-Type: application/pkcs7-signature; name=smime.p7s Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename=smime.p7s; handling=required ghyHhHUujhJhjH77n8HHGTrfvbnj756tbB9HG4VQpfyF467GhIGfHfYT6 4VQpfyF467GhIGfHfYT6jH77n8HHGghyHhHUujhJh756tbB9HGTrfvbnj n8HHGTrfvhJhjH776tbB9HG4VQbnj7567GhIGfHfYT6ghyHhHUujpfyF4 7GhIGfHfYT64VQbnj756
--boundary42-
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SIP Header Privacy and Integrity using S/MIME : Tunneling SIP
INVITE sip:[email protected] SIP/2.0 Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bKnashds8 To: Bob <sip:[email protected]> From: Anonymous <sip:[email protected]>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314159 INVITE Max-Forwards: 70 Date: Thu, 21 Feb 2002 13:02:03 GMT Contact: <sip:pc33.atlanta.com> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary=boundary42 Content-Length: 568
--boundary42 Content-Type: application/pkcs7-mime; smime-type=enveloped-data; name=smime.p7m Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename=smime.p7m handling=required Content-Length: 231
********************************************************* * Content-Type: message/sip * * INVITE sip:[email protected] SIP/2.0 * Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bKnashds8 * To: Bob <[email protected]> * From: Alice <[email protected]>;tag=1928301774 * Call-ID: a84b4c76e66710 * CSeq: 314159 INVITE * Max-Forwards: 70 * Date: Thu, 21 Feb 2002 13:02:03 GMT * Contact: <sip:[email protected]>
* Content-Type: application/sdp * v=0 * o=alice 53655765 2353687637 IN IP4 pc33.atlanta.com * s=Session SDP * t=0 0 * c=IN IP4 pc33.atlanta.com * m=audio 3456 RTP/AVP 0 1 3 99 * a=rtpmap:0 PCMU/8000 **********************************************
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