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EAP-SIM1 Using EAP-SIM for WLAN Authentication 2005-9-13.

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Presentation on theme: "EAP-SIM1 Using EAP-SIM for WLAN Authentication 2005-9-13."— Presentation transcript:

1 EAP-SIM1 Using EAP-SIM for WLAN Authentication

2 EAP-SIM2 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

3 EAP-SIM3 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

4 EAP-SIM4 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。

5 EAP-SIM5 IEEE 802.1X EAPOL Peer( 被认证者 ) Authenticator ( 认证 者 ) Lower Layer

6 EAP-SIM6 IEEE 802.1X EAPOL Peer( 被认证者 ) Pass-through Authenticator ( 认证 者 ) Authentication Server (认证服务器) Radius Protocol AAA:Authentication(认 证), Authorization (授权), and Accounting ( 记帐 ) Lower Layer

7 EAP-SIM7 GSM authentication( 认证 ) 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。

8 EAP-SIM8 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, 实际上厂商都采用了 COMP128 ,它同时实现了 A3,A8 。

9 EAP-SIM9 EAP-SIM Introduction( 简介 ) builds on underlying GSM mechanisms 构建在 GSM 认证机制之上。 Peer SIM Card AuthenticatorAAA/RADIUS GSM/MAP/SS7 Gateway SS7 Network GSM Authentication Center

10 EAP-SIM10 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。

11 EAP-SIM11 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 re- authentication procedure. 支持快速重复认证 ( 可选 )

12 EAP-SIM12 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 | |< | | |

13 EAP-SIM13 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

14 EAP-SIM14 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 ] 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。

15 EAP-SIM15 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。

16 EAP-SIM16 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。

17 EAP-SIM17 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)

18 EAP-SIM18 Example Using EAP-SIM for WLAN Authentication

19 EAP-SIM19 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)

20 EAP-SIM20 Network topological diagram ( 网络拓扑图 ) simtriplets.dat

21 EAP-SIM21 SIM Reader Installation Download the driver from 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.

22 EAP-SIM22 Configure freeradius Download freeradius from cd freeradius-1.0.4; Configure;make install; cd src\modules\rlm_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 /24 {secret= eap-sim shortname= eap-sim}

23 EAP-SIM23 Generate simtriplets.dat Run agsm2.exe. Copy IMSI,RAND,SRES,Kc to simtriplets.dat, at least 5 entries. simtriplets.dat #IMSI RAND SRES Kc ,52632FE AC D796256,8184a227,5F05b4a2CE ,ECEB1577E275414e9DD9EF98B277E54A,00fb682e,B6c0de732 56c0400 ………… Make sure insert 1

24 EAP-SIM24 Configure AP

25 EAP-SIM25 EAP-SIM plug-in installation Download wEAP-SIM from Install. Enable tracing. EnableConsoleTracing : set HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\TRACING\ EnableConsoleTracing to nozero set HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\TRACING\ wEAP-SIM\ EnableConsoleTracing to nozero EnableFileTracing: set HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\TRACING\ wEAP-SIM\ EnableFileTracing to nozero

26 EAP-SIM26 Authenticate the client

27 EAP-SIM27 References 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]

28 EAP-SIM28 问题 & 讨论


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