AMPS类比行动电话系统的安全与识别.PPT

Authentication of Kerberos andWireless Communication Abbreviation of Kerberos andTwo Simple Types of Authentication Dialogue Overview of Kerberos How To Request for Service In Another Realm 我國電子化政府公開金鑰基礎建設之整體架構 AMPS類比行動電話系統的安全與識別 AMPS一號多機(拷貝機)現況及防治: IS-95 A-KEY認證功能 GSM數位行動電話系統的安全與識別(GSM Rec. 02.09) Cryptographic Functions A3, A8 and A5in GSM Protocol GSM數位行動電話系統的安全與識別詳細步驟 Mobile Equipment(ME) Identity Procedure in GSM System Eavesdropping and Unauthorized Use are Impossible with DECT : Privacy and Authentication Security Scheme of Bluetooth Generation of Bluetooth Unit Key Generation of Bluetooth Initialization Key Authentication of Bluetooth Link Key Exchange (Unit Key) Link Key Exchange (Combination Key) Generation of Bluetooth Encryption Key Encrypted Communication of Bluetooth Unit Key Stealing IEEE 802.11b Security Wired Equivalent Privacy (WEP) Encryption WEP Decryption C ? RC4(IV,k) =( P ? RC4(IV,k) ) ? RC4(IV,k) = P = M,c(M) Check c(M) Shared key authentication Security Flaws The risks of keystream reuse If C1= P1?RC4(IV,k) and C2= P2?RC4(IV,k) then C1 ? C2 = ( P1?RC4(IV,k)) ?( P2?RC4(IV,k)) = P1 ? P2 The WEP standard recommends(but does not require) that the IV be changed after every packet. Reuse Initialization Vector The IV field used bye WEP is only 24 bits wide, nearly guaranteeing that the same IV will be reused for multiple messages. packet size 2000-byte at average 5Mbps bandwidth ( ( (2000 ?8)/(5 ?106)) ? 224)/3600=14 hours PCMCIA cards that they tested reset the IV to 0 each time it’s re-initialized, and the IV is incremented by one for each packet. Decryption Dictionaries Some access points transmit broadcast messages in plaintext and encrypted form when access control is disabled. The attacker can build a table of the keystream corresponding to each IV. It does not matter if 40 bits or 104 bits shared secret key use as the attack cente