![Definition( 定义 )
• EAP-SIM is an Extensible Authentication
Protocol (EAP) [RFC3748] mechanism for
authentication and session key
distribution using the Global System for
Mobile communications (GSM)
Subscriber Identity Module (SIM).
用 GSM-SIM 卡作为 EAP 的认证和密匙
分发机制
EAP-SIM
2](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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Eap sim
- 1. EAP-SIM Using EAP-SIM for WLAN Authentication yliqiang@gmail.com 2005-9-13 EAP-SIM 1
- 2. Definition( 定义 ) • EAP-SIM is an Extensible Authentication Protocol (EAP) [RFC3748] mechanism for authentication and session key distribution using the Global System for Mobile communications (GSM) Subscriber Identity Module (SIM). 用 GSM-SIM 卡作为 EAP 的认证和密匙 分发机制 EAP-SIM 2
- 3. EAP Introduction ( 简介 ) • EAP is an authentication framework which supports multiple authentication methods. 支持多种认证机制的认证框架。 • EAP typically runs directly over data link layers such as Point-to-Point Protocol (PPP) or IEEE 802 EAP 通常直接运行在数据链路层如 PPP 或 IEEE 802 EAP-SIM 3
- 4. EAP Introduction ( 简介 ) • EAP permits the use of a backend authentication server,with the authenticator acting as a pass-through for some or all methods and peers. EAP 允许使用后台认证服务器，把认证端作为 一些或全部认证机制的转发者。 • Conceptually, EAP implementations consist of the following components: 从概念上讲， EAP 的实现有下面这些组件构 成。 EAP-SIM 4
- 5. EAP-MD5 EAP-TLS EAP-SIM ... EAP-MD5 EAP-TLS EAP-SIM EAP Peer EAP Auth. EAP Layer EAP Layer IEEE 802.1X EAPOL IEEE Logical Link 802.1X EAPOL 802.2 PPP ... IP 802.3 802.4 802.5 802.6 802.11 ... 802.2 Logical Link Lower Layer Peer( 被认证者 ) EAP-SIM PPP 802.3 802.4 802.5 802.6 802.11 ... IP Authenticator ( 认证 者) 5
- 6. EAP-MD5 EAP-TLS EAP-SIM ... EAP Peer EAP Auth. EAP Auth. EAP Layer EAP Layer EAP Layer IEEE 802.1X EAPOL IEEE Logical Link 802.1X EAPOL 802.2 PPP IP 802.3 802.4 802.5 802.6 802.11 ... Peer( 被认证者 ) ( 认证服务器 ) AAA:Authentication( 认 证） , Authorization ( 授 权 ), and Accounting ( 记 帐) IP 802.3 802.4 802.5 802.6 802.11 ... AAA/IP Pass-through Authenticator ( 认证 者) EAP-MD5 EAP-TLS EAP-SIM Radius Protocol Authentication Server PPP Lower Layer 802.2 Logical Link ... EAP Auth. EAP Layer AAA/IP EAP-SIM 6
- 7. GSM authentication( 认证 ) RAND SIM Base Station Ki A3/A8 SRES Kc • RAND is a 128-bit random challenge issued from the base station to the mobile. RAND 是基站发给移动台 ( 手机 ) 的 128 比特长随机 数。 • SRES is a 32-bit response generated by A3 issued from the mobile to the base station SRES 是移动台 ( 手机 ) 发给基站的 32 比特长响应 , 由 A3 生成。 EAP-SIM 7
- 8. GSM authentication( 认证 ) • Kc is a 64-bit Cipher Key, used for A5. Kc 是 64 比特长密匙，由 A8 生成用于数据加密 (A5) 。 • Ki is the SIM’s 128-bit individual subscriber key. Ki 是 128 比特长 SIM 卡的密匙 ( 拥有标识 ) 。 • A3/A8 are specified by each operator rather than being fully standardized,but usually implemented together as COMP128. A3/A8 定义了算法的输入输出，具体实现由厂商决定 EAP-SIM 8 ，实际上厂商都采用了 COMP128 ，它同时实现了
- 9. EAP-SIM Introduction( 简介 ) Peer Authenticator AAA/RADIUS SS7 Network GSM/MAP/SS7 Gateway SIM Card GSM Authentication Center • builds on underlying GSM mechanisms 构建在 GSM 认证机制之上。 EAP-SIM 9
- 10. EAP-SIM Introduction( 简介 ) • Provides mutual authentication 支持相互认证。 • several RAND challenges are used for generating several 64-bit Kc keys, which are combined to constitute stronger keying material. 多次挑战生成多个 Kc, 组合起来生成更 强的相关密匙。 EAP-SIM 10
- 11. EAP-SIM Introduction( 简介 ) • EAP-SIM specifies optional support for protecting the privacy of subscriber identity using the same concept as GSM, which is using pseudonyms/temporary identifiers. EAP-SIM 支持用户身份保密 ( 可选 ) 。 • It also specifies an optional fast reauthentication procedure. 支持快速重复认证 ( 可选 ) EAP-SIM 11
- 12. EAP-SIM Full Authentication Procedure( EAP-SIM | 程完 ) Peer Authenticator | EAP-Request/Identity | |<---------------------------------------------------------| | | | EAP-Response/Identity | |--------------------------------------------------------->| | | | EAP-Request/SIM/Start (AT_VERSION_LIST) | |<---------------------------------------------------------| | | | EAP-Response/SIM/Start (AT_NONCE_MT, AT_SELECTED_VERSION)| |--------------------------------------------------------->| | | | EAP-Request/SIM/Challenge (AT_RAND, AT_MAC) |<---------------------------------------------------------| +-------------------------------------+ | | Peer runs GSM algorithms, verifies | | | AT_MAC and derives session keys | | +-------------------------------------+ | | EAP-Response/SIM/Challenge (AT_MAC) | |--------------------------------------------------------->| | | | EAP-Success | |<---------------------------------------------------------| | | 全 认 证 过 12
- 13. Key Generation • • • • MK = SHA1(Identity|n*Kc| NONCE_MT| Version List| Selected Version) K_aut , K_encr , MSK and EMSK are derived from MK using Pseudo-Random number Function (PRF) Request AT_MAC = HMAC-SHA1-128(K_aut, EAP packet| NONCE_MT) Response AT_MAC = HMAC-SHA1-128(K_aut,EAP packet| n*SRES) In the formula above, the "|" character denotes concatenation. Nonce A value that is used at most once or that is never repeated within the same cryptographic context. MAC Message Authentication Code EAP-SIM 13
- 14. Indication of vulnerabilities( 弱 点) • The security of the A3 and A8 algorithms is important to the security of EAP-SIM. Some A3/A8 algorithms have been compromised; see for example [GSM Cloning] for discussion about the security of COMP-128 version 1. Note that several revised versions of the COMP-128 A3/A8 algorithm have been devised after the publication of these weaknesses and that the publicly specified GSM-MILENAGE [3GPP TS 55.205] algorithm is not vulnerable to any known attacks. A3/A8 算法的安全性对 EAP-SIM 是至关重要的。 COMP128-v1 已经被破 解 ( 当前市面上大部分 SIM 卡用的是 COMP128-v1), 修订过的 COMP128 v2,v3 以及公开标准的 GSM-MILENAGE, 当前还没有方法攻破。 EAP-SIM 14
- 15. Indication of vulnerabilities( 弱 点) • Mutual Authentication and Triplet Exposure EAP-SIM provides mutual authentication. The peer believes that the network is authentic because the network can calculate a correct AT_MAC value in the EAP-Request/SIM/Challenge packet. To calculate the AT_MAC it is sufficient to know the RAND and Kc values from the GSM triplets (RAND, SRES, Kc) used in the authentication. Because the network selects the RAND challenges and the triplets, an attacker that knows n (2 or 3) GSM triplets for the subscriber is able to impersonate a valid network to the peer. EAP-SIM 支持双向认证。被认证者相信认证者是因为认证者能计算出正 确的 AT_MAC, 要计算 AT_MAC 知道 RAND 和 Kc 就足够了。因为是认 证者选择 RAND ，攻击者只需知道几个 (2-3)Kc 就可以假装是一个有效 的认证者。 EAP-SIM 15
- 16. Security Claims( 安全声明 ) • Auth. mechanism: EAP-SIM is based on the GSM SIM mechanism, which is a challenge/response authentication and key agreement mechanism based on a symmetric 128-bit pre-shared secret. EAP-SIM also makes use of a peer challenge to provide mutual authentication. 认证机理 :EAP-SIM 基于 GSM-SIM 的认证机理 , 它是 一种基于挑战 / 响应的认证和密匙分发机制，需要一个 预先共享的 128 比特长对称密匙 (Ki) 。 EAP-SIM 通过 被认证者发挑战 (NONCE_MT) 支持双向认证。 EAP-SIM 16
- 17. Security Claims( 安全声明 ) • • • • • • • • • • • • • • Ciphersuite negotiation: No Mutual authentication: Yes Integrity protection: Yes Replay protection: Yes Confidentiality: Yes, except method specific success and failure indications Key derivation: Yes Description of key hierarchy:(page 13) Dictionary attack protection: N/A Fast reconnect: Yes Cryptographic binding: N/A Session independence: Yes Fragmentation: No Channel binding: No Indication of vulnerabilities:(page 14,15) EAP-SIM 17
- 18. Example Using EAP-SIM for WLAN Authentication EAP-SIM 18
- 19. Requirements( 需求清单 ) • Windows XP built-in supplicant • EAP-SIM plug-in for the Windows XP built-in 802.1x Supplicant (http://weap.sf.net) • PC/SC compatible smart card reader (QWY LowSpeed CCID smart card reader) • Wireless Access Point support RADIUS (TP-LINK TL-WR541G) • RADIUS server support EAP-SIM (FreeRadius 1.0.4) EAP-SIM 19
- 20. Network topological diagram ( 网络拓扑图 ) simtriplets.dat EAP-SIM 20
- 21. SIM Reader Installation • Download the driver from http://agsm.sf.net • Insert the USB smart card reader in a USB port,specify the location of the driver. • Insert your sim-card into smart card reader,run agsm2.exe to make sure you can access the sim-card. EAP-SIM 21
- 22. Configure freeradius • Download freeradius-1.0.4 from http://www.freeradius.org • cd freeradius-1.0.4; Configure;make install; cd srcmodulesrlm_sim_files; make install. • Add the following to radiusd.conf: In modules {}, add: sim_files { simtriplets = " ${raddbdir}/simtriplets.dat " } in eap{} add sim{} In authorized {}, add: sim_files before eap. • Add the following to clients.conf client 192.168.1.0/24 {secret = eap-sim shortname= eap-sim} EAP-SIM 22
- 23. •Run agsm2.exe. simtriplets.dat #IMSI RAND SRES Kc 1460001551807128,52632FE305874545AC9936926D796256,8184a227,5F05b4a2C E884400 1460001551807128,ECEB1577E275414e9DD9EF98B277E54A,00fb682e,B6c0de73 256c0400 ………… Make sure insert 1 EAP-SIM Generate simtriplets.dat •Copy IMSI,RAND,SRES,Kc to simtriplets.dat, at least 5 entries. 23
- 25. EAP-SIM plug-in installation • Download wEAP-SIM from http://weap.sf.net • Install. • Enable tracing. EnableConsoleTracing : set HKEY_LOCAL_MACHINESOFTWAREMICROSOFTTRACING EnableConsoleTracing to nozero set HKEY_LOCAL_MACHINESOFTWAREMICROSOFTTRACING wEAP-SIM EnableConsoleTracing to nozero EnableFileTracing: set HKEY_LOCAL_MACHINESOFTWAREMICROSOFTTRACING wEAP-SIM EnableFileTracing to nozero EAP-SIM 25
- 27. References • http://www.intel.com/technology/itj/2005/volume 09issue01/art07_next_generation/p05_simpl_netw ork.htm • draft-haverinen-pppext-eap-sim-16.txt • [RFC3748] Extensible Authentication Protocol (EAP) • S5.Brumley-comp128.pdf • [GSM Cloning] http://www.isaac.cs.berkeley.edu/isaac/gsm.html EAP-SIM 27
Notes de l'éditeur
- The EAP server MAY use the leading "1" as a hint to try EAP-SIM as the first authentication method during method negotiation, rather than for example EAP/AKA. The EAP-SIM server MAY propose EAP-SIM even if the leading character was not "1".